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U.S. DEPARTMENT OF THE INTERIOR

U.S. GEOLOGICAL SURVEY

**Geologic Map of Central (Interior) Alaska**

compiled by

Frederic H. Wilson1, James H. Dover1, Dwight C. Bradley1, Florence R.
Weber2, Thomas K. Bundtzen3, and Peter J. Haeussler1

1998

Text to accompany

U.S. Geological Survey Open-File Report OF 98-133

Prepared in cooperation with the Alaska Department of Natural Resources,
Division of Oil and Gas and Division of Geological and Geophysical
Surveys

U.S. DEPARTMENT OF THE INTERIOR

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY

Charles G. Groat, Director

This report is preliminary and has not been reviewed for conformity with
U.S. Geological Survey editorial standards or with the North American
Stratigraphic Code. Any use of trade, firm, or product names is for
descriptive purposes only and does not imply endorsement by the U.S.
Government.

^1^ U.S. Geological Survey, 4200 University Dr., Anchorage AK
99508-4667;

^2^ U.S. Geological Survey, P.O. Box 80586, Fairbanks, AK 99708-0586;

^3^ Pacific Rim Geological Consulting, P.O. Box 81906, Fairbanks, AK
99708-1906

Geologic Map of Central (Interior) Alaska

Table of Contents

Introduction 1\
Acknowledgements 2

DESCRIPTION OF MAP UNITS\
GENERAL UNITS

bu Bedrock of unknown type or age 3

QUATERNARY AND LATE TERTIARY ROCKS AND DEPOSITS

Qs Surficial deposits, undifferentiated 3\
Qv Volcanic rocks, undivided 3\
QTv Volcanic rocks, undivided 3\
QTi Intrusive rocks, undivided 3

**TERTIARY ROCKS**\
**Sedimentary rocks**

Tsu Sedimentary rocks, undivided 3\
Tk Kenai Group, undivided 3\
Tsf Sterling Formation 4\
Tkb Beluga Formation 4\
Tty Tyonek Formation 4\
Tn Nenana Gravel 4\
Tcb Coal-bearing rocks 4\
Ttw Tsadaka, West Foreland, and Wishbone Formations, undivided 4\
Tts Tsadaka Formation 4\
Twf West Foreland Formation 4\
Tw Wishbone Formation 4\
Tvs Volcanic and sedimentary rocks, undivided 4\
Tfv Fluviatile sedimentary rocks and subordinate volcanic rocks 5\
Tch Chickaloon Formation 5\
Tar Arkose Ridge Formation 5\
Tovs Orca Group, undivided 5\
Tos Sedimentary rocks of the Orca Group 5\
Toc Conglomerate of the Orca Group 5\
Tov Volcanic rocks of the Orca Group, undivided 5

**Igneous rocks**\
Volcanic and hypabyssal rocks

Tvu Volcanic rocks, undivided 5\
Trs Rhyolitic volcanic and sedimentary rocks 5\
Tb Basalt 6\
Thf Hypabyssal felsic and intermediate intrusive rocks 6\
Thm Hypabyssal mafic intrusive rocks 6

**Pliocene**

Thd Hornblende dacite 6

**Miocene**

Tba Basaltic andesite 6

**Oligocene and Eocene**

Tvr Crystal and crystal-lithic ash-flow tuff 6\
Tvb Andesite and basalt 6

**Paleocene**

Tcv Volcanic rocks of the Cantwell Formation 7

Plutonic rocks

Tiv Granitic and volcanic rocks, undivided 7

**Oligocene**

Togr Granite 7

**Oligocene or Eocene**

Toegr Granitic rocks 7\
Toem Granodiorite to tonalite 7

**Eocene**

Tegr Granite and granodiorite 7\
Td Felsic intrusive rocks 7

**Paleocene**

Tpgr Granitic rocks 8\
Thgd Granodiorite and other intermediate plutonic rocks 8\
Tgl Gabbro 8

**TERTIARY AND/OR CRETACEOUS**\
**Sedimentary rocks**

TKcg Conglomerate, sandstone, and lignite 8

**Igneous rocks**\
Volcanic and hypabyssal rocks

TKv Flows, tuff, and breccia, undivided 8\
TKd Dikes and subvolcanic rocks of intermediate composition 8\
TKgp Hypabyssal granite porphyry dikes and rhyolitic sills, and plugs 8\
TKvr Rhyolite and related rocks 8\
TKvi Andesite and related rocks 9\
TKiv Mafic to intermediate volcano-plutonic complexes 9

Intrusive rocks

TKi Intrusive rocks, undivided 9\
TKg Granitic rocks 9\
TKgd Granodiorite, tonalite, and monzonite dikes, and stocks 9\
TKqd Quartz diorite and diorite dikes and stocks 9\
TKl Lamprophyre, alkali gabbro, and alkali diorite 9\
TKgb Gabbro and leucogabbro 9\
TDg Gabbro 9

**Metamorphic rocks**

TKc Melange or cataclastite of the Orca Group 9\
TKgg Gneissose granitic rocks 9\
TPza Amphibolite facies metamorphic rocks 10

**UNDIVIDED MESOZOIC ROCKS**\
**Sedimentary rocks**

KT[r]{.smallcaps}g Gemuk Group 10

**Igneous rocks**

Mzi Intrusive rocks 10\
Mzum Ultramafic and associated rocks 10

**Metamorphic rocks**

Mzsa Schist and amphibolite 11\
Mzpca Phyllite, pelitic schist, calc-schist, and amphibolite of the
MacLaren\
metamorphic belt 11

**CRETACEOUS ROCKS**\
**Sedimentary rocks**

Kcs Cantwell Formation, sedimentary rocks subunit 11\
Kms Minto unit 11\
Km Matanuska Formation 11\
Kuskokwim Group\
Kk Kuskokwim Group, deep marine rocks 12\
Kkn Kuskokwim Group, non-marine and shallow-marine rocks 12\
\
Sedimentary rocks of the Yukon-Koyukuk region \-- introduction 12\
Kme Melozitna sequence 12\
Kss Nonmarine sandstone, quartz conglomerate, shale, and siltstone 13\
Kqc Quartz-pebble conglomerate 13\
Kcg Igneous pebble-cobble conglomerate 13\
Kvm Volcanic graywacke and conglomerate 13\
Knb Norton Bay sequence 13\
Kshn Nonmarine shale, siltstone, and sandstone 13\
Ksse Marine sandstone and siltstone 13\
Kmm Marine mudstone and sandstone 13\
Kgw Graywacke sandstone and mudstone 14\
Kwcf Wilber Creek flysch 14\
Kvgm Volcanic graywacke and mudstone 14\
Ksm Quartz-carbonate sandstone and pebbly mudstone 14\
Knl Nelchina Limestone 14\
Kb Berg Creek Formation 14

**Melange**

KT[r]{.smallcaps}m McHugh Complex 15\
Kmar Melanges of the Alaska Range 15\
T[r]{.smallcaps}Sl Limestone blocks 15\
mlu Ultramafic and associated rocks 15

**Igneous rocks**\
Volcanic and hypabyssal rocks

Kvl Volcanic rocks 16\
Ktg Volcaniclastic rocks 16\
Kve Andesite and related rocks 16

Intrusive rocks

Kg Granitic rocks 16\
Kmum Mafic and ultramafic rocks 16\
Ktt Leucotonalite and trondhjemite 16

**Metamorphic rocks**

Kvs Metasedimentary rocks of the Valdez Group 17\
Kvv Metavolcanic rocks of Valdez Group 17

**CRETACEOUS AND/OR JURASSIC**\
**Sedimentary rocks**

KJw Wolverine quartzite 17\
KJwc Wilber Creek flysch and Wolverine quartzite, undivided 17\
KJs Argillite, chert, sandstone, and limestone 17\
KJf Kahiltna flysch sequence 17\
KJfk Flysch sequence 18\
KJfn Flysch sequence 18\
KJfm Metasedimentary rocks 18\
KJcg Conglomerate, sandstone, siltstone, shale, and volcanic rocks 18\
KJvr Vrain unit 19

**Intrusive rocks**

KJg Granitic rocks 19

**Metamorphic rocks**

KJhc Haley Creek metaplutonic and metasedimentary rocks 19

**JURASSIC**\
**Sedimentary rocks**

Jn Naknek Formation 19\
Jct Chinitna Formation, Tuxedni Group, and coeval sedimentary rocks 19\
Jc Chinitna Formation 20\
Jkt Kotsina Conglomerate 20\
Jtx Tuxedni Group 20

**Igneous rocks**

Jmu Mafic and ultramafic rocks 20\
Jtr Trondhjemite 21\
Ji Alaska-Aleutian Range and Chitina Valley batholiths, undifferentiated
21

**Metamorphic rocks**

Jsch Greenschist and blueschist 21\
Jps Pelitic schist 22\
JPaur Uranatina metaplutonic complex 22

**JURASSIC AND TRIASSIC**\
**Sedimentary rocks**

JT[r]{.smallcaps}lm Limestone and marble 22\
JT[r]{.smallcaps}mc McCarthy Formation 22

**Igneous rocks**

JT[r]{.smallcaps}tk Talkeetna Formation 22

**TRIASSIC**\
**Sedimentary rocks**

T[r]{.smallcaps}ls Chitistone and Nizina Limestones, undivided 22\
T[r]{.smallcaps}sl Spiculite and sandy limestone 22\
T[r]{.smallcaps}cs Calcareous sedimentary rocks 22\
T[r]{.smallcaps}cg Conglomerate and volcanic sandstone 23\
T[r]{.smallcaps}ps Phosphatic shale and limestone 23\
T[r]{.smallcaps}sc Black shale and chert 23

**Igneous Rocks**\
Volcanic rocks

T[r]{.smallcaps}n Nikolai Greenstone and related rocks 23

Plutonic rocks

T[r]{.smallcaps}c Carbonatite 23\
T[r]{.smallcaps}gb Gabbro, diabase, and metagabbro 24

**Metamorphic rocks**

T[r]{.smallcaps}nm Metavolcanic and associated metasedimentary rocks 24

**MESOZOIC AND PALEOZOIC**\
**Assemblages and Sequences**

Chulitna sequence \-- introduction 24\
JT[r]{.smallcaps}su Red and brown sedimentary rocks and basalt 24\
JT[r]{.smallcaps}ct Crystal tuff, argillite, chert, graywacke, and
limestone 24\
T[r]{.smallcaps}lb Limestone and basalt sequence 24\
T[r]{.smallcaps}r Red beds 25\
T[r]{.smallcaps}Dv Volcanic and sedimentary rocks 25\
Dsb Serpentinite, basalt, chert and gabbro 25

Oceanic rocks of the Seventymile, Angayucham, Tozitna, and Innoko\
assemblages \-- introduction 25\
\
Seventymile assemblage\
JPsu Ultramafic rocks 25\
JPzsgs Greenstone and chert 25

Angayucham assemblage\
Jaum Ultramafic rocks 25\
JMab Basalt and chert 26

Tozitna assemblage north of the Kaltag Fault\
JMtru Greenstone, chert, and ultramafic rocks, undivided 26\
JT[r]{.smallcaps}tmu Mafic and ultramafic rocks 26\
T[r]{.smallcaps}Mts Sedimentary rocks 26

Tozitna assemblage south of the Kaltag Fault\
JMtu Mafic, ultramafic, and sedimentary rocks, undivided 27\
Jtu Ultramafic rocks, undivided 27\
JPztm Mafic and ultramafic rocks, undivided 27\
T[r]{.smallcaps}Mtqp Quartzite and phyllite 27\
T[r]{.smallcaps}Mtsu Sedimentary rocks, undivided 27

Innoko assemblage\
Jium Ultramafic and mafic rocks, undivided 27\
JT[r]{.smallcaps}ta Cherty tuff, crystal and lithic tuffs,\
and volcanic breccia 27\
T[r]{.smallcaps}Mis Sandstone, grit, and argillite 28\
T[r]{.smallcaps}Mica Chert, argillite, and volcaniclastic rocks 28\
Pig Graywacke 28\
MDl Fine-grained limestone 28

**Stratigraphic sequences**

Mystic sequence\
JDm Mystic stratigraphic sequence, undivided 29\
JT[r]{.smallcaps}tv Tatina River Volcanics and equivalent units 29\
PMl Younger limestone 29\
PDsc Sheep Creek Formation and correlative siliciclastic units 29\
Dsc Shale and chert 29\
Dml Older limestone 29

Mystic and Dillinger stratigraphic sequences, undivided\
JCmd Mystic and Dillinger stratigraphic sequences, undivided 30\
DSmdl Unnamed limestone 30

**Sedimentary rocks**

T[r]{.smallcaps}Ps Sedimentary rocks, undivided 30\
T[r]{.smallcaps}Pas Flysch-like sedimentary rocks 30

**Igneous rocks**

MzPzi Intrusive and volcanic rocks, undivided 31\
MzZum Ultramafic and mafic rocks, undivided 31

**Metamorphic rocks**

JPzk Kakhonak Complex 31

**PALEOZOIC**\
**Assemblages and Sequences**

Skolai Group \-- introduction 31\
Pe Eagle Creek Formation 32\
PPasc Station Creek and Slana Spur Formations, and equivalent rocks 32\
Pat Tetelna Volcanics 32\
Pmi Shallow stocks, dikes, and sills 32\
PPagi Ahtell pluton 32\
PPad Diorite complex 32\
Pagb Gabbro and orthogneiss 32\
PPast Strelna metamorphic complex 33\
PPaskm Marble 33

Dillinger and Nixon Fork sequences \-- introduction 33\
Dillinger sequence\
DCd Dillinger sequence, undivided 33\
Dsbr Barren Ridge Limestone and correlative units 34\
Stc Terra Cotta Mountains Sandstone and correlative units 34\
SCpl Post River Sandstone, Lyman Hills Formation, and\
correlative units 34

Nixon Fork sequence\
DZn Shallow-marine carbonate units of Holitna basin area, undivided 34\
DSwc Whirlwind Creek Formation and unnamed correlative units 34\
Spf Paradise Fork Formation and unnamed correlative rocks 34\
Ont Novi Mountain and Telsitna Formations, and unnamed\
correlative rocks 35\
CZds Unnamed dolostone, sandstone, siltstone 35

**Sedimentary rocks**

Pzlc Limestone and chert 35\
Ps Argillite, siltstone, sandstone, and minor conglomerate 35\
PDms Sedimentary rocks 35\
Mgq Globe quartzite 35\
Dps Phyllite, slate, siliceous siltstone, and argillite 36\
Dcb Cascaden Ridge, Beaver Bend, and correlative rocks 36\
Dq Quail unit 36\
Dtr Troublesome unit and possibly correlative rocks 36\
Ds Schwatka limestone unit 36\
Dsv Volcanic part of Schwatka unit 36\
DSlc Lost Creek unit 37\
DSl Limestone 37\
DSt Tolovana Limestone 37\
SZa Amy Creek unit 37\
Oc Chert 38\
Ocl Limestone 38

**Igneous rocks**

Pzvs Volcanic and sedimentary rocks 38\
Ofc Fossil Creek Volcanics 38

**Metamorphic rocks**

PMpc Phyllite and chert 38\
Dy Yanert Fork sequence and correlative rocks 38\
Dys Fine-grained schistose sedimentary rocks 38\
Dyv Fine-grained schistose volcanic rocks 39\
Pzsc Spruce Creek sequence and correlative rocks 39\
Pzlsl Schist, phyllite, limestone, and greenstone 39

**PALEOZOIC AND PRECAMBRIAN**\
**Sequences and Complexes**

Yukon-Tanana, Alaska Range, and Ruby metamorphic complexes \--
introduction 39\
Yukon-Tanana and northern Alaska Range metamorphic complex\
Pzydm Dolostone and marble 39\
Pze Eclogite-bearing schist 40\
MDyao Augen orthogneiss 40\
MDt Totatlanika Schist 40\
MDtm Mylonitic Totatlanika Schist 40\
Pzk Keevy Peak Formation 40\
Pzkcp Calcareous and phyllitic rocks 41\
PzZym Mafic schist 41\
PzZyqs Quartz- and pelitic schist of the Yukon-Tanana Upland 41\
PzZaqs Pelitic and quartzose schist of the Alaska Range 41\
PzZysa Schist and amphibolite 42\
PzZyg Gneiss 42\
PzZygs Gneiss, schist, and quartzite 42

Ruby metamorphic complex\
Pzrm Marble 42\
Pzrmi Metamorphosed mafic igneous rocks 42\
MDrao Augen orthogneiss 43\
Dm Marble 43\
PzZrqs Pelitic and quartzitic schist 43\
PzZrpg Quartzofeldspathic paragneiss and quartzite 43

**Sedimentary rocks**

CZw Wickersham grit, undivided 43\
CZwl Wickersham limestone 44\
CZwa Argillaceous upper unit 44\
Zwg Gritty lower unit 44

**PRECAMBRIAN**\
**Metamorphic rocks**

ZYnm Metamorphic basement rocks of the Nixon Fork\
sequence, undivided 44\
ZYns Pelitic schist 44\
ZYnc Calc-schist 44\
ZYnv Metavolcanic rocks 45\
Ynqd Meta-quartz diorite 45\
Xi Idono metamorphic complex 45

References cited 46\
List of map sources 56\
Anchorage 56\
Big Delta 56\
Circle 56\
Fairbanks 56\
Gulkana 56\
Healy 57\
Iditarod 57\
Kantishna River 57\
Kateel River 57\
Lime Hills 57\
Livengood 57\
McGrath 58\
Medfra 58\
Mount Hayes 58\
Mount McKinley 58\
Melozitna 59\
Nulato 59\
Ophir 59\
Ruby 59\
Sleetmute 59\
Talkeetna 60\
Talkeetna Mountains 60\
Tanana 60\
Tyonek 60\
Valdez 61

Index of map units 62

Appendix A. Exploratory drillholes in Central (Interior) Alaska A-1\
(after p. 63)

**Geologic Map of Central (Interior) Alaska**

compiled by

> Frederic H. Wilson, James H. Dover, Dwight C. Bradley, Florence R.
> Weber, Thomas K. Bundtzen, and Peter J. Haeussler

Introduction

This map and associated digital databases are the result of a
compilation and reinterpretation of published and unpublished 1:250,000-
and limited 1:125,000- and 1:63,360-scale mapping. The map area covers
roughly 416,000 km2 (134,000 mi2) and encompasses 25 1:250,000-scale
quadrangles in central Alaska. The compilation was done as part of the
U.S. Geological Survey National Surveys and Analysis project, whose goal
is nationwide assemble geologic, geochemical, geophysical, and other
data. This map is an early product of an effort that will eventually
encompass all of Alaska, and is the result of an agreement with the
Alaska Department of Natural Resources, Division of Oil And Gas, to
provide data on interior basins in Alaska. Two geophysical maps that
cover the identical area have been published earlier: *Bouguer gravity
map of Interior Alaska* (Meyer and others, 1996); and *Merged
aeromagnetic map of Interior Alaska* (Meyer and Saltus, 1995).

Compilation of this map began in September 1996, using published
1:250,000-scale mapping. As the project progressed, published maps at
other scales and unpublished mapping were incorporated as we built an
integrated map. Description and correlation of geologic units to produce
map units was an iterative process that continued through technical
review to publication. Digital files of the final compilation of each of
the 25 1:250,000-scale quadrangles are provided on this CD-ROM. Cited in
the text and on the map are the map sources we used; additional map
sources are listed in Galloway and Laney (1994).

It takes little imagination to realize that many compromises have been
made in strongly held beliefs to allow construction of this compilation.
Yet even our willingness to make interpretations and compromises does
not allow us to resolve mapping conflicts in some areas. Therefore,
there are a number of areas on the map where it was necessary to
separate map units by \"quadrangle boundary faults.\" More time and
fieldwork may allow resolution of these conflicts. We believe that this
map and its problems present a very good argument to justify and support
further work in this area and elsewhere in Alaska. Nonetheless, we hope
that geologists who have mapped in central Alaska will recognize that in
incorporating their work, our regional correlations have required
generalizing and lumping of units. Lead efforts on the map compilation
were as follows: Cenozoic and Mesozoic sedimentary rocks and igneous
rocks, Frederic Wilson; Paleozoic sedimentary rocks, Dwight Bradley;
metamorphic rocks, James Dover; with supporting efforts for all rock
types in the northeast and central part of the map area by Florence
Weber; the southwest part of the map area by Tom Bundtzen; and the
Tyonek area by Peter Haeussler.

Compiling this map was complicated because the original source maps were
made by different generations of geologists, mapping with very different
ideas. A few of the older maps were completed before the concepts of
plate tectonics or accreted (suspect) terranes. On the other hand, some
of the more recent maps were so governed by terrane analysis that
conventional stratigraphic nomenclature was not used and is obscured.
For the present compilation, we adopted a traditional stratigraphic
approach and have avoided use of the controversial and inconsistently
defined term \"terrane.\" Our decision to adopt a traditional approach
is reflected in a map that emphasizes age and lithology of map units,
rather than differences among fault-bounded packages of rocks. For a map
of the present scope and scale, the traditional approach seems to have
more to offer to a wider variety of users. It is far easier to construct
a terrane map from a traditional geologic map than vice-versa. One
conception of the map area from a terrane point of view is that of
Silberling and others (1994), shown as figure 2 on sheet 3 of this
compilation. Another can be found in Nokleberg and others (1994). It
will be apparent from examination of figure 2 that our lumpings of units
results in a map having divisions only loosely similar to Silberling and
others (1994)

Some of our groupings of map units use terms previously applied by other
geologists to terranes. We instead use such terms as \"sequence\"
\"assemblage,\" and \"complex\" for groups of rock units characterized
by a common history or environment. Sequences, as used here, are groups
of sedimentary rock units that display a coherent and consistent
stratigraphy and association. Assemblages consist of a mixture of
sedimentary, igneous, and(or) metamorphic rock units within a still
recognizable stratigraphic framework that may be tectonically internally
disrupted. Complexes are generally restricted to igneous or metamorphic
rock assemblages and may have no apparent stratigraphic framework. An
exception, however is the McHugh Complex, a tectonic melange in southern
Alaska whose name is in common use.

In general, where terminology for lithologic packages of rock units has
come into common usage and where we could justify or support its
continued usage, we have used that terminology. An example of such a
lithologic association is the Nixon fork sequence. The ease with which
this is done is in part dependent on our knowledge or perceived
understanding of the rock units. This packaging occurs at either extreme
of our spectrum of knowledge. Thus, packaging very old metamorphic rocks
is relatively easy because we don\'t know any better. In other cases,
such as the Nixon Fork sequence, we have reasonably good constraints on
the nature of the rock units and can confidently package them.

In the following descriptions, units are generally listed in
chronological order from youngest to oldest. In the unit descriptions,
the age of the units, rather than their apparent stratigraphic position
is given after the unit label and name. In the text of the descriptions,
lower and upper is used to denote stratigraphic position, whereas late
and early indicate age. Within each major age category, sequences,
assemblages, and complexes are listed first, followed by sedimentary,
igneous, and metamorphic rock units, listed in order of increasing age.

In general, metamorphic rock units are listed in increasing order of
their inferred or interpreted protolith age, which in many cases is
subject to significant uncertainty. In the limited number of cases for
which we cannot interpret a protolith age the metamorphic rocks are
listed by increasing age of metamorphism, either known or inferred.

Acknowledgements

There is no way that a compilation on this scale could be done without
the assistance of many geologists, far more knowledgeable about the
geology of various regions of Alaska than we are. We have benefited
greatly from the opportunity to use unpublished mapping by and to
consult with Grant Abbott, Robert M. Chapman, Julie A. Dumoulin, Cynthia
Dusel-Bacon, Bruce M. Gamble, Anita Harris, Marti L. Miller, Madelyn
Millholland, Warren J. Nokleberg, Donald H. Richter, William W. Patton,
Jr., Gary R. Winkler, and Wesley K. Wallace. In addition, support and
encouragement from many of our peers, including Donald Grybeck, Thomas
D. Light, and Alison B. Till, have made what at times seemed an
overwhelming task, seem more possible and desirable.

The project to produce this map had short deadlines and would not have
been possible without the able support of Nora Shew and her GIS support
staff. Catherine G. Baxter, Kelly M. Brunt, Nathan S. Pannkuk, James D.
Hall, S.M. Weems, Dolly Perea, and David Dempsey each made invaluable
contributions to the project and helped us to meet our deadlines.

The Alaska Department of Natural Resources, Division of Oil and Gas
provided strong encouragement and financial support to help with the
preparation of this map; its assistance was invaluable in seeing to it
that the map was completed.

In addition, organizational support from the Alaska Department of
Natural Resources, Division of Geological and Geophysical Surveys is
greatly appreciated. Particularly, support and unpublished data made
available by Ellie E. Harris and Rocky R. Reifenstuhl have helped to
improve the map significantly.

Technical and editorial review of all or part of the manuscript by John
C. Reed, Jr. and Henry C. Berg were greatly appreciated and have helped
to improve the text and map.

**DESCRIPTION OF MAP UNITS**

\[Note: Quadrangles are 1:250,000 scale unless otherwise noted.\]

GENERAL UNITS

**bu Bedrock of unknown type or age**\-- Includes rubble of
metasiltstone and chert in the Kantishna River quadrangle and other
areas of unknown bedrock throughout map area \[symbol 10\] unit 99

QUATERNARY AND LATE TERTIARY ROCKS AND DEPOSITS

**Qs Surficial deposits, undifferentiated** (Quaternary)\--
Unconsolidated silt, sand, and gravel of fluvial, glacial, colluvial,
and other origins \[symbol 21\] 100

**Qv Volcanic rocks, undivided** (Quaternary)\-- Basalt to rhyolite
flows, pyroclastic deposits, lahar deposits, and other volcanic
deposits. Located in the south central part of map area. Largely
associated with the Wrangell group of volcanoes in the Gulkana
quadrangle (Nokleberg and others, in press), but also includes the
northernmost of the Cook Inlet volcanoes in the Tyonek quadrangle
(Miller and Smith, 1976; Magoon and others, 1976) \[symbol 12\] 300 305

**QTv Volcanic rocks, undivided** (Quaternary and Late Tertiary)\--
Includes the Wrangell Lava consisting chiefly of basalt and andesite in
the southeastern part of the map area and olivine basalt and vesicular
andesite in the northern part of the map area (Nokleberg and others, in
press) \[symbol 410\]

**QTi Intrusive rocks, undivided** (Quaternary and Late Tertiary)\--
Rhyolitic to andesite domes, dikes swarms and plugs and other intrusive
rocks exposed chiefly in the Wrangell Mountains (Nokleberg and others,
in press) \[symbol 78\]

TERTIARY ROCKS\
Sedimentary rocks

**Tsu Sedimentary rocks, undivided** (Tertiary)\-- Includes a number of
different units mapped in various areas throughout the map area:\
In the Healy quadrangle, unit Ts (Csejtey and others, 1992) consists of
a sequence of poorly consolidated fluviatile dark-gray shale,
yellowish-gray sandstone, siltstone, and pebble conglomerate of possible
Eocene to Miocene age that may be in part correlative with the Tertiary
coal-bearing sequence (unit Tcb).\
In the Mount Hayes quadrangle, units Ts and Tsc of (Nokleberg and
others, 1992a), consist of (unit Ts) brown sandstone and graywacke and
interbedded conglomerate and argillite of possible Oligocene to Pliocene
age and (unit Tsc) light-colored, fine-grained, poorly sorted sandstone,
of Eocene to Miocene age, locally containing interbedded siltstone,
pebbly sandstone, pebble to cobble conglomerate, and sparse, thin coal
layers. Unit Tc of Nokleberg and others (1992a) consists of poorly
sorted, crudely bedded to massive, polymictic conglomerate and
subordinate sandstone. Assigned age of unit Tc is Eocene? because unit
locally overlies volcanic rocks of Eocene age.\
In the Circle quadrangle (Foster and others, 1983), unit Tcs consists of
gray or tan conglomerate that grades into gray, tan, or iron-oxide
stained sandstone.\
In the Big Delta quadrangle (Weber and others, 1978), consists of
light-gray poorly consolidated, poorly bedded fine to very coarse
conglomerate, olive-gray, brown, or orange-brown coarse- to fine-grained
sandstone and olive-gray siltstone.\
In the Talkeetna Mountains quadrangle, unit Tsu, consists of fluviatile
conglomerate, sandstone, and claystone which contain a few interbeds of
lignitic coal and which may be correlative with the Chickaloon Formation
(Csejtey and others, 1978)\
In the McGrath quadrangle, consists of thick- to thin-bedded moderately
indurated sandstone interbedded with poorly indurated, laminated,
fissile, carbonaceous shale and fine-grained sandstone (Bundtzen and
others, 1997a). Also included in map unit is limestone conglomerate of
the McGrath quadrangle, unit Tcl of Bundtzen and others (1997a).
Assigned age is pre-middle Eocene for the sandstone and shale unit as
unit is intruded by a middle Eocene dike, whereas the limestone
conglomerate unit is assigned an age of late Paleocene? to Oligocene
\[symbol 88\] 500 unit Ts, HE002; GU002; units Ts, Tc, and Tsc, MH002;
unit Tcs, CI002; BD002; unit Tsu, TK002; units Ts, Tcl, MG002; unit
Tclg, MG003

**Tk Kenai Group, undivided** (Pliocene to Oligocene)\-- Poorly to
moderately indurated pebble to cobble conglomerate, cross-bedded
medium-grained sandstone to granule conglomerate, clay layers, and coal
seams as much as 5 m thick (Solie and others, 1991). Consists of rocks
assigned to the Beluga, Sterling, and Tyonek Formations and other
unassigned fluvatile sedimentary rocks of Pliocene to Oligocene age.
Units are typically estuarine and nonmarine clastic sedimentary rocks.
Tertiary formations assigned to Kenai Group in the Cook Inlet basin by
Calderwood and Fackler (1972). Locally subdivided into: \[symbol 85\]
560

**Tsf Sterling Formation** (Pliocene)\-- Orange, light-tan, or
light-gray, massive-bedded, coarse conglomerate \[symbol 85+13\] 540

**Tkb Beluga Formation** (Miocene)\-- Sandstone, siltstone, and coal
\[symbol 85+14\] 545

**Tty Tyonek Formation** (Miocene)\-- Carbonaceous sandstone, siltstone,
shale, and claystone. Locally divided into two members, a sandstone
member consisting of about 80 percent tan to light-gray sandstone, 20
percent light- to medium-gray siltstone and claystone, and less than 1
percent conglomerate, coal, and volcanic ash. Conglomerate member
consists of 40 percent conglomerate, 20 percent sandstone, and less than
40 percent siltstone, claystone, and coal. Also includes the Hemlock
Conglomerate of Oligocene age where units are undivided \[symbol 85+15\]
600

**Tn Nenana Gravel** (Pliocene and late(?) Miocene)\-- Yellowish-gray to
reddish-brown well-sorted, poorly to moderately consolidated
conglomerate and coarse-grained sandstone having interbedded mudflow
deposits, thin claystone layers, and local thin lignite beds widely
distributed on the north side of the Alaska Range. Unit is more than
1,300-m-thick and moderately deformed (Csejtey and others, 1992; Bela
Csejtey, written commun., 1993) \[symbol 37\] 570

**Tcb Coal-bearing rocks** (Miocene? to Paleocene?)\-- Healy Creek,
Sanctuary, Suntrana, Lignite Creek, and Grubstake Formations of the
Nenana coal field, the sedimentary rocks of the Jarvis Creek coal field
of Nokleberg and others (1992a), which have been divided into three
members, and similar units in other Tertiary basins; located largely
north of the Alaska Range. \"The coal-bearing rocks comprise terrestrial
cyclic sequences, in varying proportions, of siltstone, claystone,
mudstone, shale, generally cross-bedded and pebbly sandstone, both
arkosic and quartz-rich, subbituminous coal and lignite, and minor
amounts of dominantly quartz- and chert-pebble conglomerate (Csejtey and
others, 1992)\" \[symbol 30\] 640, 910 unit Tcb HE002; TL002; FB002;
BD002; unit Ts TN002; TN003; KH003; UL002; unit Tscg, MZ002; units Tjc,
Tjcl, Tjcm, Tjcu, Tcf, and Tcg, MH002; unit Tcg, MG003

**Ttw Tsadaka, West Foreland, and Wishbone Formations, undivided**
(Tertiary)\-- Also includes unnamed fluvatile conglomerate and
coal-bearing sandstone of the eastern Talkeetna Mountains. Locally
subdivided into: \[symbol 35\] 790

**Tts Tsadaka Formation** (Miocene or Oligocene)\-- Poorly sorted cobble
to boulder conglomerate, interbedded with lenses of feldspathic
sandstone, siltstone, and shale. Unit is of terrestrial origin,
deposited on alluvial fans and in braided streams from a northerly
source. Clasts in the conglomerate are largely plutonic in contrast to
the underlying Wishbone Formation. Age considered Oligocene on the
Anchorage quadrangle geologic map (Winkler, 1992) and Miocene on the
Talkeetna Mountains quadrangle geologic map (Csejtey and others, 1978)
\[symbol 35+13\] 670

**Twf West Foreland Formation** (Eocene)\-- Conglomerate, sandstone, and
siltstone; mostly tuffaceous (Magoon and others, 1976) (TY002) \[symbol
35+14\] 855

**Tw Wishbone Formation** (Eocene)\-- Fluviatile conglomerate having
thick interbeds of sandstone, siltstone, and claystone and containing
local partings of volcanic ash. Deposited in a similar environment as
the overlying Tsadaka Formation; however source terrain was largely
volcanic, most likely the Talkeetna Formation (AN002, TY002) \[symbol
35+15\] 870

**Tvs Volcanic and sedimentary rocks, undivided** (Oligocene and
Eocene)\-- Light to medium greenish-gray to gray conglomerate,
graywacke, siltstone, lignitic shale and bituminous coal (Weber and
others, 1992). Also includes greenstone, basalt, and tuff interlayered
with medium- to medium-dark-olive-gray graywacke and conglomerate
grading upward to siltstone in the northern part of the Livengood
quadrangle. Isom Creek section is overturned to the north. Unit may be
in part correlative with units Tcb and Tfv of this map \[symbol 85+13\]
795, Tvs, LG002

**Tfv Fluviatile sedimentary rocks and subordinate volcanic rocks**
(early Eocene?)\-- Intercalated fluviatile sequence of conglomerate,
sandstone, siltstone, and mudstone, and a few thin, interlayered flows
of basaltic andesite found in the Healy quadrangle (Csejtey and others,
1992). Finer grained parts contain carbonized plant fragments. Csejtey,
(comment in Csejtey and others, 1992) suggests possible correlation with
the Cantwell Formation. Other possible correlations are with units Tvs
(preferred) and Tcb of this map. Unit as shown on map also includes
similar units in the McGrath (Bundtzen and others, 1997a) and Mount
Hayes (Nokleberg and others, 1992a) quadrangles \[symbol 85+15\] 880

**Tch Chickaloon Formation** (Eocene and Paleocene)\-- Predominantly
fluviatile and alluvial carbonaceous mudstone, siltstone, conglomeratic
sandstone, and polymictic conglomerate (Winkler, 1992). Locally, upper
and middle parts of unit contain numerous beds of bituminous coal. Lower
part of unit largely conglomerate and lithic sandstone derived from
erosion of the Talkeetna Formation. Thickness is more than 1,500m
\[symbol 91\] 900

**Tar Arkose Ridge Formation** (Eocene, Paleocene, and Late
Cretaceous?)\-- Fluviatile and alluvial feldspathic and biotitic
sandstone, conglomerate, siltstone, and shale containing abundant plant
fragments. Deposition in a coarsening upward sequence was on alluvial
fans and by overloaded braided streams carrying sediment derived from
rapid erosion of uplifted mountains to the north. Thickness is as much
as 700m. Age control is largely based on late Paleocene fossil plants
and radiometric ages on locally associated volcanic flows and dikes. A
pre-Tertiary age has been suggested for the part of the unit based on a
questionable K-Ar age determination on biotite from a metamorphosed part
of the unit (Csejtey and others, 1977; 1978); otherwise the age is
considered broadly coeval with the Chickaloon Formation (Winkler, 1992)
\[symbol 136\] 890

**Tovs Orca Group, undivided** (Eocene and Paleocene)\-- Thick complexly
deformed accretionary sequence of flysch and tholeiitic volcanic rocks
(Winkler, 1992). Consists of basaltic flows, pillow breccia, and tuff
interbedded with flyschoid siltstone and sandstone. Outcrops within the
Valdez and Anchorage quadrangles. Locally sub-divided into: \[symbol
40\] 951

**Tos Sedimentary rocks of the Orca Group**\-- Monotonous sequence of
thin- to thick-bedded sandstone, siltstone, and mudstone. Primary
sedimentary features indicate deposition by turbidity currents (Winkler,
1992) \[symbol 40+15\] 950

**Toc Conglomerate of the Orca Group**\-- Massive, clast-supported
pebble, cobble, and boulder conglomerate grading to matrix-supported
pebbly mudstone and sandstone (Winkler, 1992) \[symbol 40+16\] 952

**Tov Volcanic rocks of the Orca Group, undivided** (Eocene? and
Paleocene)\-- Tholeiitic pillow basalt, pillow breccia, and minor
aquagene tuff. Volcanic rocks are conformable with enclosing flyschoid
sedimentary rocks and on a regional scale the tholeiitic rocks are
lenticular in form (Winkler and others, 1981) \[symbol 416\] 1135

Igneous rocks\
Volcanic and hypabyssal rocks

**Tvu Volcanic rocks, undivided** (Tertiary)\-- Includes unit Tvv of the
Healy quadrangle (Csejtey and others, 1992), consisting of volcanic
flows ranging from basalt to rhyolite in composition, pyroclastic rocks
and subordinate subvolcanic intrusive rocks. Similar volcanic rocks
occur as unit Tv in the Anchorage and Talkeetna Mountains quadrangles,
where they also include small lenses of fluviatile conglomerate. A crude
stratification is described (Csejtey and others 1978; Winkler, 1992),
where felsic rocks and pyroclastic rocks occur stratigraphically lower
and basaltic and andesitic flows occur in the upper part of the section.
In the Lime Hills quadrangle (Gamble and Reed, 1996), small \"volcanic
intrusive\" centers of unit Tvi are included in this unit. Age control
is sparse and unit is generally considered to range throughout the
Tertiary; however most K-Ar age determinations are Eocene and older. In
the Nulato quadrangle, this unit includes Patton\'s (written commun.,
1997) unit Tr, rhyolite and dacite flows and shallow intrusive bodies
and unit Ta, andesite and basalt flows, both of Eocene and Paleocene age
\[symbol 413\] 1000

**Trs Rhyolitic volcanic and sedimentary rocks** (Tertiary?)\--
Rhyolitic volcanic and minor(?) associated sedimentary rocks are mapped
in a small area in the Tanana quadrangle (Chapman and others, 1982;
Dover, unpublished data, 1997). Rhyolitic rocks consist of light- to
very light-yellow and yellowish-gray to cream and white flows and
breccia. Tuff and probable welded tuff, generally devitrified, are
common and similar in color to the lavas. Sedimentary rocks include
minor light- to medium-gray cherty rocks and very light-yellow to tan
and light-olive- to medium-gray, generally thin-bedded to laminated
siltstone and shale, grading to argillite \[symbol 413+14\] 1001

**Tb Basalt** (early Tertiary?)\-- Brownish black olivine basalt.
Vesicular in part, locally displays columnar jointing and possibly
pillow structures in the Sleetmute quadrangle (Miller and others, 1989);
also includes olivine basalt in the Livengood, Fairbanks and Lime Hills
quadrangles \[symbol 413+13\] 1004 (Tb, SM002; LG002; FB002; LH004)

**Thf Hypabyssal felsic and intermediate intrusive rocks** (Miocene to
Paleocene, mostly Early Tertiary or Eocene?)\-- Includes unit Ti in the
Anchorage (Winkler, 1992) and unit Tif, both of apparent Eocene age, in
the Valdez (Winkler and others, 1980) and Talkeetna Mountains (Csejtey
and others, 1978) quadrangles. Consists of small stocks, dikes, and
sills of rhyolite to dacite. Also includes similar rocks in the Healy
(Csejtey and others, 1992), Mount McKinley (Bela Csejtey, Jr., written
commun., 1993) and Big Delta (Weber and others, 1978) quadrangles. In
the McGrath quadrangle (Bundtzen and others, 1997) unit includes units
Tid, Tif, and Tia, dikes and sills of a wide range of compositions but
largely felsic to intermediate composition \[symbol 237+13\] 1010 1011

**Thm Hypabyssal mafic intrusive rocks** (Miocene to Paleocene, mostly
Early Tertiary or Eocene?)\-- Widely exposed small stocks and
irregular-shaped dikes and sills of diorite porphyry, diabase, basalt
and lamprophyre. Includes unit Tim, of apparent Eocene age, in the
Anchorage (Winkler, 1992) and Talkeetna Mountains (Csejtey and others,
1978) quadrangles. Also includes similar rocks in the Healy (unit Tvim,
Csejtey and others, 1992) and Mount McKinley (unit Tvim, Bela Csejtey,
Jr., written commun., 1993) quadrangles, and unit Td, porphyritic to
equigranular andesite and basalt dikes in the Lime Hills quadrangle
(Reed and Gamble, 1988). Unit also tentatively includes unit TJds of the
Anchorage quadrangle (Winkler, 1992) consisting of mafic to intermediate
dikes, sills, stocks, for which Tertiary to Jurassic age was assigned
Winkler (1992) \[symbol 345\] 1012 Tim, TJds (AN002); Tvim (HE002,
MM002); Td (LH002)

Pliocene

**Thd Hornblende dacite**\-- Subvolcanic intrusive hornblende dacite of
Jumbo dome in the Healy quadrangle. K-Ar age 2.79 +/- 0.25 Ma age
(Csejtey and others, 1992) \[symbol 76\] 1022

Miocene

**Tba Basaltic andesite**\-- Very fine-grained to aphanitic, dark- to
medium-gray, locally vesicular basaltic andesite. K-Ar ages 6.9 +/- 0.2
and 13.0 +/- 0.5 Ma (Miller and Bundtzen, 1994) \[symbol 420\] 1052

Oligocene and Eocene

**Tvr Crystal and crystal-lithic ash-flow tuff** (early Oligocene to
late Eocene)\-- Tuff and subordinate flows and hypabyssal intrusive
rocks of apparently felsic composition in small exposures in the eastern
Lime Hills and the Melozitna quadrangles. Also includes local
accumulations of volcaniclastic sedimentary rocks. In some areas of the
Lime Hills quadrangle, rocks range from andesite to dacite in
composition, in general the composition was not reported (Gamble and
Reed, 1996). Units included here consist of the informally defined
Seabee, Lime Hills A-2, Snowcap, North Volcanic Center, and Styx River
Volcanics of Gamble and Reed (1996). In the Melozitna quadrangle,
includes rocks formerly mapped by Patton and others (1978) in their unit
TKv, now know to be of Tertiary age. Exposures are found in the Indian
River, Takhakhdona Hills, and Dulbi River areas of the Melozitna
quadrangle \[symbol 365\] 1070

**Tvb Andesite and basalt** (Oligocene and Eocene)\-- Andesite breccia
and tuff called the Mount Galen Volcanics (Gilbert, 1979) that is the
eruptive equivalent of the Mount Eielson pluton. K-Ar age of 38 Ma
(Gilbert, 1979). Includes a variety of volcanic rocks assigned to the
Sheep Creek, Windy Fork, and Terra Cotta volcanic fields by Bundtzen and
others (1997a). Also includes the Roundabout Mountain volcanic field
(see description of unit KJv, Patton, 1966), composed of mildly deformed
vesicular basalt and pyroclastic rocks in the Kateel River quadrangle.
According Moll-Stalcup and others (1994), the Roundabout Mountain
volcanic field is andesite of 30-45 Ma age. W.W. Patton, Jr. (oral
commun., 1997) explained that the age range of the volcanic field was
assigned by inference from the Takhakhdona and Indian Mountain volcanic
fields to the east (Moll-Stalcup and others, 1994) \[symbol 365\] 1081

Paleocene

**Tcv Volcanic rocks of the Cantwell Formation**\-- Intercalated,
moderately deformed, sequence of andesite, altered basalt, rhyolite, and
dacite flows, felsic pyroclastic rocks and minor sandstone and
carbonaceous mudstone largely in the Healy quadrangle (Csejtey and
others, 1992). K-Ar ages are typically Paleocene, although some are as
young as Eocene. The Teklanika Formation is sometimes used in the
literature as a synonym for this unit. Herein includes, unit Tv of
Nokleberg and others (1992a), which consists chiefly ash-flow tuff,
breccia, agglomerate, flows, dikes, and sills in the Mount Hayes
quadrangle. Also includes minor volcanic sandstone, conglomerate, and
fossiliferous limestone. Nokleberg and others (1992a) refer this unit to
the Eocene on the basis of a single whole-rock 49 Ma K-Ar age
determination on a rhyodacite tuff \[symbol 416\] 1140

Plutonic rocks

**Tiv Granitic and volcanic rocks, undivided** (Oligocene to
Paleocene)\-- Extensive border zone between a Tertiary granitic
batholith (unit Tgr of this map) and slightly younger felsic dikes and
small subvolcanic intrusive bodies that cut the pluton. Also includes
erosional remnants of rhyolitic flows overlying the pluton (unit Tgrv,
Csejtey and others, 1992) in the south central Healy quadrangle \[symbol
279\] 1210

Oligocene

**Togr Granite**\-- Biotite-bearing peralkaline alkali-feldspar granite
and biotite-plagioclase granite of 29 to 31 Ma age and biotite or
biotite-amphibole granite of 25 to 27 Ma age in the Lime Hills (units
Twf, Tnep, Gamble and Reed, 1996), McGrath (unit Twg, Bundtzen and
others, 1997a) and Tyonek quadrangles. Unit also includes biotite
granite of 32 Ma age in the Anchorage quadrangle (unit Tmg, Winkler,
1992) \[symbol 270\] 1270

Oligocene or Eocene

**Toegr Granitic rocks** (early Oligocene or late Eocene)\-- Includes a
wide variety of granitic rocks exposed throughout much of the southern
part of the map area. Rocks range from alkali-feldspar granite, through
biotite or biotite-hornblende granite to granodiorite and minor quartz
monzonite. Locally, the rocks are porphyritic and hypabyssal. Rocks of
the unit are exposed in the Lime Hills quadrangle (Gamble and Reed,
1996) as well as the Mount Hayes (Nokleberg and others, 1992a), and
Anchorage (Winkler, 1992) quadrangles. Also included are small quartz
monzonite plutons of the southeastern Sleetmute quadrangle (Miller and
others, 1989). Radiometric ages on these plutons range from about 34 Ma
to as much as 45 Ma, however most of the plutons yield ages of about 38
Ma \[symbol 180\] 1290

**Toem Granodiorite to tonalite** (early Oligocene or late Eocene)\--
Biotite, biotite-hornblende, and hornblende granodiorite, quartz
diorite, and quartz monzodiorite. Rocks of the unit are exposed in the
Lime Hills (Gamble and Reed, 1996), Mount McKinley (Bela Csejtey, Jr.,
written commun., 1993), Talkeetna (Reed and Nelson, 1980), and Anchorage
quadrangles (Winkler, 1992) \[symbol 423\] 1292

Eocene

**Tegr Granite and granodiorite**\-- Undated biotite-hornblende granite
and granodiorite and altered biotite and hornblende tonalite yielding
ages about 45 Ma in the Valdez quadrangle (units Tg and Tt, Winkler and
others, 1980); biotite-hornblende granodiorite dated at 44 and 48 Ma in
the Talkeetna Mountains quadrangle (unit Tgd, Csejtey and others, 1978);
and porphyritic hornblende granodiorite dated at 52.8 Ma in the Iditarod
quadrangle (unit Tp, Miller and Bundtzen, 1994) \[symbol 177\] 1300,
1310

**Td Felsic intrusive rocks**\-- Widely distributed leucocratic dikes,
sills, and small stocks south of Border Ranges fault in the Anchorage
quadrangle (Winkler, 1992). Bodies are generally thin, but some have
lateral extents of several kilometers; some can be traced as far as 30
km across the strike of the enclosing Valdez Group. Dacite is the most
common composition, rhyolite is also present. Radiometric ages fall in
two clusters, one at 55-48 Ma and another at 44-43 Ma. However, a dike
near Anchorage crosscutting the Valdez Group (unit Kvs) and McHugh
Complex (unit KT[r]{.smallcaps}m) yielded a 34.8 Ma age \[symbol
177+13\]

Paleocene

**Tpgr Granitic rocks**\-- Widely distributed biotite-muscovite granite
to quartz monzonite. Granitic rocks of this unit in the southern part of
the map area are part of the informally defined McKinley Sequence
(Gamble and Reed, 1996) in the Lime Hills quadrangle (Gamble and Reed,
1996) yielding radiometric ages between 57 and 65 Ma and in the
Talkeetna quadrangle dated at 56 to 52 Ma and 65 to 64 Ma (Reed and
Nelson, 1980) are also part of the unit. Farther north, 60
million-year-old quartz monzonite plutons in the Livengood quadrangle
(Weber and others, 1992), 62 to 65 million-year-old plutons in the
Tanana quadrangle (Chapman and others, 1982), and a 55 Ma granite pluton
in the Mount Hayes quadrangle (unit grgr, Nokleberg and others, 1992a)
are all part of this unit \[symbol 361\]

**Thgd Granodiorite and other intermediate plutonic rocks**\-- Consists
of biotite and biotite-hornblende granodiorite, largely in the southern
part of the map area. Includes an unnamed quartz diorite pluton (58 Ma)
and the Mount Estelle pluton of the Lime Hills (Gamble and Reed, 1996)
and Talkeetna (Reed and Nelson, 1980) quadrangles, plutons in the
western and northern parts of the Talkeetna Mountains quadrangle
(Csejtey and others, 1978), all generally yielding ages between 61 and
66 Ma. Also includes a number of small monzonite or monzodiorite bodies
in the Livengood quadrangle (unit Tm, Weber and others, 1992) \[symbol
273\]

**Tgl Gabbro** (Paleocene)\-- Dark-colored, fine- to medium-grained
hornblende and pyroxene-hornblende gabbro (62 Ma) in the Lime Hills A-2
1:63,360-scale quadrangle (Gamble and Reed, 1996) \[symbol 372\]

TERTIARY AND/OR CRETACEOUS\
Sedimentary rocks

**TKcg Conglomerate, sandstone, and lignite** (Tertiary(?) and
Cretaceous)\-- Rocks exposed in a 25-m-thick section along the Sethkokna
River in the Medfra quadrangle (Patton and others, 1980). Conglomerate
contains clasts of quartz, chert, felsic volcanic rocks, and
talc-schist. Unit is overlain by rhyolite and dacite flows of the
*Volcanic rocks of the Sischu Mountains* unit (included in unit TKvr
here). Provisionally assigned a Latest Cretaceous age
(Campanian-Maestrichtian) on the basis of pollen in the lignite beds.
\[symbol 749\]

Igneous rocks\
Volcanic and hypabyssal rocks

**TKv Flows, tuff, and breccia, undivided**\-- Basaltic, andesitic, and
rhyolitic flows, tuff, and breccia and a few dacite flows, minor
interbedded sandstone and shale. Exposed primarily in the Ruby and Ophir
quadrangles (Cass, 1959; Chapman and Patton, 1979; Chapman and others,
1985). Unit also includes unit TKvd, dacite flows and dikes; and unit
TKvt, intermediate composition tuff of the Veleska Lake volcanic field
of Bundtzen and others (1997a) in the McGrath quadrangle and felsic tuff
of the Tyonek quadrangle (Solie and others, 1991) (unit TKe, RB002; unit
TKv, RB003; OP002; unit TKvt, MG002; unit TKft, TY004, TY005; unit TKir,
SM002) \[symbol 126\] 1600 1615

**TKd Dikes and subvolcanic rocks of intermediate composition**\--
Exposed in widely scattered areas throughout map area. Includes
pilotaxitic dacite-andesite plugs in the Iditarod quadrangle (Miller and
Bundtzen, 1994) \[symbol 126+15\] 1620, 1601

**TKgp Hypabyssal granite porphyry dikes and rhyolitic sills, and
plugs**\-- Exposed in widely scattered areas \[symbol 126+16\] 1602

**TKvr Rhyolite and related rocks**\-- Consists of light gray to pink
rhyolitic volcanic rocks and minor dacite, including flows, tuff,
welded(?) tuff and breccia. Exposures of this unit include the volcanic
rocks of the Big Creek \-- Tokatjikh Creek area of the Melozitna
quadrangle (mapped as unit TKv by Patton and others, 1978), the
northwestern part of the Tanana quadrangle, the Nowitna River and Nixon
Fork-Upper Sulukna River areas, and the Sischu Mountains and northeast
in the Medfra (Patton and others, 1980), Ruby (Cass, 1959), Mount
McKinley (Bela Csejtey, Jr., written commun., 1993), Tanana (Chapman and
others, 1982), and Kantishna River quadrangles (Chapman and others,
1975). Also includes felsic volcanic rocks associated with
volcano-plutonic complexes of the Sleetmute quadrangle, as mapped by
Miller and others (1989) and rhyolitic tuff and dacite dikes of the
Veleska Lake volcanic field of Bundtzen and others (1997a). Where
determined, age ranges between approximately 70 and 50 Ma \[symbol
126+13\] 1603, 1604, and 1625

**TKvi Andesite and related rocks**\-- Largely andesite but includes
minor dacite and basalt flows, tuff, and breccia. Consists of that part
of the Iditarod Volcanics that overlie the sedimentary rocks of the
Kuskokwim Group (unit Kk) in the Iditarod quadrangle. Also includes the
\"Volcanic rocks of the Yetna River,\" also in the Iditarod quadrangle
(Miller and Bundtzen, 1994), and the \"Volcanic rocks of the Nowitna
River\" area of the Medfra quadrangle (Patton and others, 1980),
basaltic andesite of Veleska Lake volcanic field of Bundtzen and others
(1997a) (ID002; unit TKa, KH002) \[symbol 126+14\] 1605

**TKiv Mafic to intermediate volcano-plutonic complexes**\-- Chiefly
altered basaltic andesite and trachyandesite porphyry flows and
hypabyssal intrusive bodies. Mostly in the southwestern part of the map
area, in the Iditarod, Sleetmute, and Medfra quadrangles. Ages range
between approximately 71 and 65 Ma \[symbol 129\] 1630

Intrusive rocks

**TKi Intrusive rocks, undivided**\-- Composition ranges from granite to
diorite. Radiometric ages not available for most bodies. Largely in the
southwestern and western part of the map area \[symbol 241\] 1650

**TKg Granitic rocks**\-- Widely distributed and exposed granitic
intrusive rocks, chiefly biotite and biotite-hornblende granite.
Includes lesser granodiorite, quartz monzonite and alkali granite
\[symbol 244\] 1655

**TKgd Granodiorite, tonalite, and monzonite dikes, and stocks**\--
Limited to the southeastern part of the map area, except for the
monzonite bodies, which tend to occur farther west and north. Available
K-Ar radiometric ages range from 59 to 75 Ma \[symbol 362\] 1660

**TKqd Quartz diorite and diorite dikes and stocks**\-- Fine- to
medium-grained, hypautomorphic granular quartz diorite and diorite dikes
and stocks. Mapped only in the Mount Hayes quadrangle (Nokleberg and
others, 1992a) \[symbol 666\] 1665

**TKl Lamprophyre, alkali gabbro, and alkali diorite**\-- Mapped in the
Mount Hayes quadrangle \[symbol 644\] 1690

**TKgb Gabbro and leucogabbro**\-- Fine- to medium-grained
hypidiomorphic granular textured gabbro and leucogabbro, typically in
small plutons. Mapped in the Lime Hills (Gamble and Reed, 1996) and
Talkeetna Mountains (Csejtey and others, 1978) quadrangles. Age is
poorly constrained \[symbol 667\] 1670

**TDg Gabbro** (Tertiary? to Devonian?)\-- Medium- to coarse-grained
gabbro with minor diorite and basalt which intrude(?) rocks of inferred
Triassic to Mississippian age and locally, Cretaceous age. Contact
relations are uncertain due to poor exposure but Chapman and others
(1985) indicate at least one gabbro body is clearly intrusive and has a
hornfels aureole. A similar unit of gabbroic sills, dikes, and small
plugs in the adjoining Medfra quadrangle was given a provisional
Tertiary to Devonian age. Includes unit TMg the Ophir quadrangle
(Chapman and others, 1985) and unit TDg in the Medfra quadrangle (Patton
and others, 1980) \[symbol 667\] 1680 unit TMg, OP002; unit TDg, MD002

Metamorphic rocks

**TKc Melange or cataclastite of the Orca Group** (Tertiary and
Cretaceous)\-- Extensive serpentinized ultramafic rocks, including
dike-like bodies of rodingite, blocks of layered gabbro, crossite
schist, pillow basalt, marble, chert and diverse other rock types.
Conglomerate clasts within unit resemble lithologies in the Chickaloon
Formation (Winkler and others, 1980; Winkler, 1992). Chert clasts are of
probable Late Triassic or Early Jurassic age. Emplacement of the melange
or cataclastite is inferred to have been during Cretaceous or Tertiary
time. Outcrops within the Valdez and Anchorage quadrangles \[symbol
736\] 1710

**TKgg Gneissose granitic rocks** (early Tertiary to Early?
Cretaceous)\-- Chiefly gneissose granodiorite, quartz diorite, and minor
granite referred to as the East Susitna batholith in the Mount Hayes
quadrangle (Nokleberg and others, 1992a). In the Talkeetna Mountains
quadrangle, Csejtey and others (1978), mapped an early Tertiary
andalusite and(or) sillimanite-bearing pelitic schist, lit-par-lit
migmatite, and granite unit we have included here. In the Healy
quadrangle, Csejtey and others (1992) mapped similar rocks as part of
their unit Kgr, which is in part correlative with the East Susitna
batholith of Nokleberg and others (1992a). The granitic bodies show
moderately to well-developed flow foliation and all internal contacts
between phases are gradational as well as the contact with unit Mzpca.
Unit has pervasive schistosity generally striking northeast to southwest
and dipping moderately to steeply west, is locally blastomylonitic and
contains relict porphyritic textures. Metamorphic grade is middle to
upper amphibolite facies. Radiometric ages, including U-Pb zircon and
sphene and K-Ar mica and hornblende ages have a wide range, between
about 70 and 29 Ma (Nokleberg and others, 1992a; Csejtey and others,
1978; 1992). Youngest ages are close to and may be related to unroofing
along the Denali fault system. In the Healy quadrangle, rocks of this
unit are included in unit Kgr, Cretaceous granitic rocks. South of the
Susitna Glacier, these rocks are described as migmatitic and thought to
reflect lit-par-lit intrusion of Tertiary magma into Cretaceous plutons.
The youngest ages for this unit tend to occur in close proximity to the
Denali Fault. In the Lime Hills and Tyonek quadrangles, unit TKgs,
gneiss is included in this unit. An orthogneiss as above, its texture
appears mylonitic. Composition is primarily granodiorite, however up to
5 percent garnet was noted locally in contrast to the gneiss of the
Mount Hayes and Healy quadrangles. Structural grain strikes northeast to
southwest and tends to be vertical or dip steeply (80°) to the northwest
\[symbol 209\] 1720

**TPza Amphibolite facies metamorphic rocks** (Earliest Tertiary to
Paleozoic)\-- Dominantly medium- to medium-dark-gray garnetiferous
quartz-mica schist and amphibolite, but includes slate and shale in the
Livengood quadrangle. Locally has gneissic texture. Minor marble and
very minor quartzite occur in unit in the Tanana quadrangle. Unit
outcrops as large fault slivers or \"lozenges\" along a strand of the
Tintina-Kaltag fault system in the Livengood (Weber and others, 1992)
and Tanana quadrangles (Reifenstuhl and others, 1997). In the Tanana
quadrangle, geophysical interpretation cited in Reifenstuhl and others
(1997) and outcrop patterns suggest a steep northwest contact with rocks
of the Tozitna assemblage and a moderately southeast dipping southeast
contact. Protolith age is unknown and although Reifenstuhl and others
(1997) and Dusel-Bacon and others (1989) suggest a Ruby or Yukon-Tanana
metamorphic complex origin, Weber and others (1992) suggest a possible
protolith of Tozitna sedimentary rocks. Includes the Raven Creek Hill
unit of Weber and others (1992) and units pTam, pTas, pTaq of
Reifenstuhl and others (1997) (unit MzPzr, LG002; unit Pzsr?, TN002;
KH003; unit Pzs (Pzqs), TN003) \[symbol 81\] 5208

UNDIVIDED MESOZOIC ROCKS\
Sedimentary rocks

**KT[r]{.smallcaps}g Gemuk Group** (Early Cretaceous to Late Jurassic
and Triassic to Mississippian?)\-- Chiefly massive and thin-bedded,
fine-grained, siliceous rocks, includes some volcanic rocks, calcareous
siltstone, and limestone. Miller and others (1989) described Gemuk Group
in the Sleetmute quadrangle as chiefly siltstone interbedded with lesser
chert and volcanic rocks and minor limestone, graywacke and breccia.
Only Early Cretaceous and Cretaceous fossils are known from the
Sleetmute quadrangle. Early Cretaceous, Late Jurassic, and Triassic to
Mississippian(?) fossils have been collected from the Gemuk Group (Hoare
and Coonrad (1959a) elsewhere. Originally defined by Cady and others
(1955), Hoare and Coonrad (1959a, b) subdivided the unit in the Bethel
and Russian Mission quadrangles. Box and others (1993) described rocks
of this unit in the Bethel and southern Russian Mission area as a series
of distinct terranes and further subdivided it \[symbol 973\] 4710

Igneous rocks

**Mzi Intrusive rocks** (Mesozoic?)\-- Undated parts of the
Alaska-Aleutian Range batholith in the Tyonek quadrangle. Chiefly quartz
diorite, diorite, and gabbro (Reed and Elliott, 1970) \[symbol 375\]
4800, 4880

**Mzum Ultramafic and associated rocks** (Mesozoic?)\-- Chiefly variably
serpentinized pyroxenite, peridotite, dunite, schistose amphibolite and
hornblende-plagioclase gneiss derived from gabbro (Nokleberg and others,
1992a). Exposed close to the Denali Fault and along the Broxson Gulch
thrust in the Mount Hayes quadrangle. Protolith thought Paleozoic,
metamorphosed in the Early Cretaceous. K-Ar analysis of biotite and
hornblende from pyroxenite yielded nearly concordant ages of 123 and 126
Ma (Nokleberg and others, 1992a) \[symbol 674\] 4890, 4891

Metamorphic rocks

**Mzsa Schist and amphibolite** (Late Cretaceous or older?)\--
Dominantly fine- to medium-grained garnet-bearing schist and hornblende
amphibolite, with subordinate calc-silicate schist and quartzite, and
intercalated gneissose granitic to gabbroic metaigneous rocks. Includes
migmatitic rocks of the MacLaren metamorphic belt (Smith, 1981) near
East Susitna batholith (unit TKgg). Metamorphic grade increases
gradationally eastward and northward toward the East Susitna batholith
(unit TKgg). Underwent amphibolite facies and local greenschist facies
retrogressive metamorphism. K-Ar hornblende and biotite ages range from
65.9 to 31.9 Ma, with biotite yielding the consistently youngest ages.
Includes the sa, mig, and mgsh units in the MacLaren terrane of
Nokleberg and others (1992a) in the Mount Hayes quadrangle. We interpret
rocks originally mapped as the Kahiltna flysch sequence by Csejtey and
others (1992) in the southeastern part of the adjacent Healy quadrangle
to the west, had the same protolith as these units. We have therefore
placed those rocks in this unit \[symbol 793+14\] 5205 \[see 2850\]

**Mzpca Phyllite, pelitic schist, calc-schist, and amphibolite of the
MacLaren metamorphic belt** (Mesozoic)\-- Mainly phyllite, quartz-mica
schist, calc-schist, amphibolite, and subordinate marble and
meta-andesite, derived from siltstone, graywacke, marl, andesite, and
gabbro. Underwent amphibolite facies metamorphism and local greenschist
retrograde metamorphism, and at least two phases of folding having
opposite vergence. Metamorphic grade appears to increase gradationally
eastward from the Healy to Mount Hayes quadrangles, and from south to
north across a series of thrust faults mapped within the Mount Hayes
quadrangle, toward the gneissose granitic rocks of unit TKgg. K-Ar mica
ages range from 48.0 to 30.6 Ma and an amphibole age was 69.6 Ma
(Nokleberg and others, 1992a). Separated from unit Mzsa, schist and
amphibolite, by the Meteor Peak fault, and distinguished lithologically
from unit Mzsa by its calcareous component. Includes the msh, mph, and
ma units of Nokleberg and others (1992a) in the MacLaren metamorphic
belt of the Mount Hayes quadrangle. A lithologically similar part of the
Kahiltna flysch sequence (KJf) of Csejtey and others (1992) in the
southeastern part of the Healy quadrangle has been correlated on this
compilation with the above units of Nokleberg on the basis of mapping in
the Healy A-1 (Smith, 1981) and A-2 (Smith and others, 1984)
quadrangles. This correlation includes units Ks, Kp, pJa, pJt, and pJcg
of Smith (1981) and Smith and others (1984). Rocks of this unit are
considered by most workers as part of the MacLaren metamorphic belt
(Smith, 1981; Smith and others, 1984; Csejtey and others, 1992;
Nokleberg and others, 1992a) \[5206, 5210, 5215, change colors to
793+15\] Added 7 polygons in HECOMP and 1 in TKCOMP to 5210 from 2850.

CRETACEOUS ROCKS\
Sedimentary rocks

**Kcs Cantwell Formation, sedimentary rocks subunit** (Paleocene(?) and
Late Cretaceous)\-- Unit consists of a fluviatile, intercalated
sequence, in various proportions, of dominantly polymictic conglomerate,
sandstone (including arkose), siltstone, argillite, shale, and a few
thin coal beds Csejtey and others (1992). Locally thin volcanic flows
and thin tuff layers are present. Conglomerate clast lithology varies
greatly within the outcrop area, indicating different geologic source
areas and deposition by a number of river systems. Plant fossils suggest
a Paleocene age; however some K-Ar ages suggest the unit might locally
contain strata of Cretaceous age (Csejtey and others, 1992) and recent
palynological analyses reported by Ridgeway and others (1994) suggest an
early Campanian to late Maestrichtian age for the Cantwell and a
thickness of as much as 4,000 m. As mapped here, unit also includes
continental sedimentary rocks that crop out in the Talkeetna quadrangle.
These consist of chiefly medium- to dark-gray phyllitic shale,
sandstone, grit, and conglomerate containing minor carbonaceous shale
and tuffaceous sandstone \[symbol 749\] 1920

**Kms Minto unit** (Late Cretaceous(?)\-- Interbedded yellowish-gray,
iron-stained siltstone, light-gray to light-yellowish-gray mudstone
locally containing pyritized plant fragments, light- to
medium-olive-gray, very fine- to medium-grained graywacke, hard
quartzo-feldspathic sandstone, light-yellowish-gray shale, and
medium-dark-gray clay shale. Grain size fines and bedding thins
upsection. Load casts, bioturbation and burrows occur locally. Unit
reflects deltaic to continental shelf depositional conditions. Age
control is imprecise, unit thought post-Albian \[symbol 940\] 1980 Tiny
unit

**Km Matanuska Formation** (Late Cretaceous (Maestrichtian) to late
Early Cretaceous (Albian)\-- Well-indurated, thinly-bedded, dark-gray
fossiliferous shallow marine shale containing conspicuous calcareous
concretions, volcanic-lithic siltstone, sandstone, graywacke, and
subordinate conglomerate. Diverse shallow to deep marine (in part,
turbiditic) deposits derived from a northern source, either an
unidentified mid-Cretaceous magmatic arc or the Jurassic arc represented
in part by the Talkeetna Formation (Winkler, 1992). Upper part of unit
is coeval with the flysch of the Valdez Group to the south. Rests with
pronounced angular unconformity on Early Cretaceous and older strata
(Csejtey and others, 1978) \[symbol 800\] 2010

**Kuskokwim Group**\-- Divided into:

**Kk Kuskokwim Group, deep marine rocks** (Late Cretaceous and late
Early Cretaceous)\-- Sandstone, siltstone, shale, and conglomerate.
Includes fine- to coarse-grained, greenish-gray to gray, thinly
cross-bedded sandstone and quartz-chert pebble conglomerate having
poorly exposed interbeds of dark shale and siltstone. Locally, light- to
medium-gray, fine- to coarse-grained, resistant turbiditic sandstone and
medium to dark-gray shale and siltstone displaying graded bedding,
cross-bedding, flute clasts, and ripple marks. Includes 15 to 40 percent
shale and siltstone. Bouma ABCD and BCDE intervals are present. Also
includes well-indurated volcaniclastic sandstone containing as much as
40 percent volcanic clasts; locally siliceous, and very resistant in
outcrop. May be lateral equivalent of agglomerate, chert, tuff, and
sandstone unit herein included in the Kuskokwim Group volcanic rocks
(mapped here as unit Kvl). Flysch trace fossil *Paleodictyon* abundant
locally. Woody fragments, plant stems, dicotyledon leaf fragments, and
*Inoceramus* prisms locally abundant (Bundtzen and Laird, 1980, 1982;
cited in Chapman and others, 1985). Unit is widely distributed in
southwestern Alaska (see Decker and others, 1994). Mapped as units Ksu
and Ksc in Medfra (Patton and others, 1980), unit Kks in Iditarod
(Miller and Bundtzen, 1994), unit Kk in Sleetmute (Miller and others,
1989), unit Kku in Lime Hills (T.K. Bundtzen, unpublished data, 1998),
units Ku, Kss, and Kls in Ophir (Chapman and others, 1985), and units
Kcs, Kss, Kls, Kus, and Ksh in McGrath (T.K. Bundtzen, unpublished data,
1998) quadrangles. In the Lime Hills quadrangle, distinction between the
Kuskokwim Group and the Kahiltna flysch sequence (unit KJf) is difficult
and placement of the boundary is controversial

**Kkn Kuskokwim Group, non-marine and shallow-marine rocks** (early Late
Cretaceous)\-- Predominantly very fine- to medium-grained, medium- to
medium-dark-gray and greenish-gray, in part calcareous, graywacke and
sandstone(?), medium-dark gray siltstone and shale, and minor granule to
pebble polymictic conglomerate. Unit is the non-marine facies of the
Kuskokwim Group and is recognized in the Ophir (Chapman and others,
1985), Iditarod (Miller and Bundtzen, 1994), Medfra (Patton and others,
1980), McGrath, and Sleetmute (T.K. Bundtzen, unpublished data, 1998)
quadrangles. Commonly thin-bedded; weathers to various shades of yellow,
brown, and red. Largely shallow marine to nonmarine and unfossiliferous
(Chapman and others, 1985)

**Sedimentary rocks of the Yukon-Koyukuk region** (late Early Cretaceous
to Late Cretaceous)\-- Thick packages of very similar sedimentary rocks
are found rimming the Yukon-Koyukuk region which in the past were called
the Bergman or Shaktolik Group. However, both names have since been
abandoned (Patton, 1973). These rocks consist of turbiditic basin fill
covered by deltaic marine and nonmarine sedimentary rocks that prograded
over the turbidites largely from the east in the map area, but also from
the west, west of the map area. Right lateral offset along the Kaltag
Fault has juxtaposed rocks of the eastern Kobuk-Koyukuk sub-basin
against rocks of the western Lower Yukon sub-basin (Patton and others,
1994a). This map shows the rocks of the two sub-basins as different
units, informally called the Melozitna and Norton Bay sequences in order
to clearly show the distinction. The deltaic rocks of the Melozitna
sequence, from the Kobuk-Koyukuk sub-basin are proportionally thicker
and as a result this group contains a higher percentage of conglomerate,
which in itself contains a higher proportion of metamorphic and granitic
clasts.

**Kme Melozitna sequence** (Late Cretaceous to late Early Cretaceous)\--
Graywacke, shale, grit, and conglomerate. Lower part consists of shallow
marine sandstone and shale that grades upward into nonmarine dark-gray
to green sandstone, siltstone, shale, and quartz-chert pebble
conglomerate. Locally, coal beds are reported (Martin, 1926, p. 407).
Similar, unnamed unit, has been described in the Unalakleet (Patton and
Moll-Stalcup, 1996), Nulato (W.W. Patton, Jr., written commun., 1997),
and Ophir quadrangles (Chapman and others, 1985). Cretaceous sedimentary
rocks of unit Ksu of Patton (written commun., 1997) south of the Kaltag
Fault or east of the Koyukuk Flats in the Nulato quadrangle are here
mapped as part of this unit, but rocks of unit Ksu north of the Kaltag
Fault are mapped as unit Knbg. This distinction is made because
descriptions from the source maps suggest a mixed granitic and
metamorphic source for rocks south of the Kaltag Fault and a volcanic
rock dominated source north of the Fault. Many of the rocks in this unit
were originally included in the now abandoned Shaktolik Group (Patton,
1973). Locally subdivided into: \[symbol 848\] 2020 unit Ks, ID002; and
others

**Kss Nonmarine sandstone, quartz conglomerate, shale, and siltstone**
(Late(?) Cretaceous)\-- Olive-green, fine- to coarse-grained,
cross-bedded, quartzose sandstone and grit; quartz-pebble conglomerate,
and dark micaceous shale and siltstone. Interbedded fine-grained to
gritty, dark-gray to green graywacke and mudstone. Abundant plant
debris. Probably correlative with Upper Cretaceous nonmarine strata in
Kateel River quadrangle (Patton and others, 1978; Patton, 1966) \[symbol
848+16\] 1941 \[Melo\]

**Kqc Quartz-pebble conglomerate** (early Late Cretaceous)\-- Light-gray
quartz-pebble conglomerate and quartzose sandstone containing minor
intercalated ashy tuff. Intruded by granodiorite of Late Cretaceous
(\~82 Ma) age. Limited areal extent in the northeast quadrant of the
Melozitna quadrangle \[symbol 848+14\] 1990 \[Melo if you want to\]

**Kcg Igneous pebble-cobble conglomerate** (Late Cretaceous? and
Albian)\-- Massive, poorly sorted conglomerate having pebble- to
cobble-sized clasts chiefly of mafic intrusive and extrusive rocks and
chert of various colors. Locally clasts of quartz, quartzite, granitic
rocks, schist, and limestone are abundant but otherwise only occur in
minor amounts. Interbedded fine-grained to gritty, dark-gray to green
graywacke and mudstone. Grades upward into unit Kss and in part overlies
and in part laterally gradational with unit Kvgm (Patton and others,
1978). Unit thought largely Albian but may include beds as young as Late
Cretaceous (Patton and others, 1978) \[symbol 848+15\] 2030 *probable*
Melo*, also see unit Kvm below*

**Kvm Volcanic graywacke and conglomerate** (early Late or late Early
Cretaceous?)\-- Poorly sorted, fine- to coarse-grained graywacke,
sandstone, grit, and pebble- to cobble conglomerate composed chiefly of
volcanic rock and chert detritus in the Medfra and Ophir quadrangles
(Patton and others, 1980; Chapman and others, 1985)). Contains locally
abundant large *Inoceramus*, brachiopods, and worm tubes. Includes
massive volcanic conglomerate mapped as part of unit Kgs of Patton
(1966) in the northwesternmost Kateel River quadrangle. This
conglomerate is probably gradational with coarse breccia and agglomerate
of unit Kve \[symbol 983\] (KT002, shown as part of unit Kgs; unit Kvg,
MD002; OP002 \[*According to Patton, oral commun., 1997*\]) 2180, 2181

**Knb Norton Bay sequence** (Late Cretaceous to late Early
Cretaceous)\-- Marine and nonmarine deltaic shale, siltstone, and
sandstone. Northwestern part of the map area; locally subdivided here as
nonmarine Kshn and marine Ksse. Also includes units Kgw and Km described
below. In the Kateel River quadrangle, the juxtaposition of the various
rock units of the Norton Bay sequence is probably due to thrusting,
followed by normal faulting (W.W. Patton, Jr., oral commun, 1998) (unit
Ksu, NL003; unit Knm, KT002 \[*see also 2115*\]) \[symbol 797\] 1805

**Kshn Nonmarine shale, siltstone, and sandstone** (Late Cretaceous)\--
Dark-gray to olive-gray micaceous shale and siltstone, and
light-olive-gray to yellowish-orange, fine- to coarse-grained
cross-bedded sandstone. Massive sandstone beds near base of units forms
resistant ridges. North of the Kateel River, sandstone contains
pyroclastic debris. White quartz and dark chert pebble conglomerate
lenses near base of unit. Bituminous coal beds as much as 6 inches \[10
to 15 cm\] thick are present in unit as are abundant plant fossils. Unit
has an estimated thickness of 5,000 feet \[1,500 m\] (Patton, 1966)
(unit Kn, KT002) \[symbol 797+16\] 1943 \[Shak\]

**Ksse Marine sandstone and siltstone** (Early Cretaceous, Albian)\--
Littoral and offshore marine deposits of dark-gray shale and siltstone
interbedded with subordinate dark-greenish-gray fine-grained sandstone
in lower part and light-olive fine- to coarse-grained sandstone in upper
part. Local volcanic conglomerate at contact with unit Kve, andesitic
volcanic rocks. Sandstone better sorted and more quartzose than unit Km,
below. Albian age assigned on the basis of abundant molluscan fauna,
particularly the occurrence of *Inoceramus altifluminis McLearn*
(Patton, 1966) (unit Km, KT002; unit Km, NL003) \[symbol 803\] 2101
\[*Both Melozitna and Norton Bay sequences*\]

**Kmm Marine mudstone and sandstone** (Early Cretaceous, Albian)\--
Chiefly medium- to dark-gray mudstone and medium-gray to
dark-greenish-gray moderately to highly calcareous fine-grained
sandstone. Sandstone is composed largely of mafic and intermediate
volcanic detritus, including some pyroclastic material, but locally
contains lenses of feldspar and chert grit. Mudstone commonly banded and
finely cross-bedded. Age assignment based on the occurrence of
*Gastropilites*. Unit interpreted as prodelta turbidite (W.W. Patton,
Jr., oral commun., 1998) (unit Kgm, KT002; unit Kcs, NL003 \[303\])
\[symbol 803+13\] 2152

**Kgw Graywacke sandstone and mudstone** (Cretaceous, Albian{?} in
part)\-- Chiefly dark-greenish-gray to pale-olive tuffaceous and
feldspathic fine- to very coarse-grained sandstone and subordinate
dark-gray mudstone. Abundant lenses of feldspar and chert grit.
Sandstone composed largely of mafic and intermediate volcanic detritus,
including some pyroclastic material. Unit interpreted as submarine fan
turbidite (W.W. Patton, Jr., oral commun., 1998) (unit Kgs, KT002)
\[symbol 797+15\] 2117

**Kwcf Wilber Creek flysch** (Albian)\-- Interlayered siltstone, shale,
sandstone, and conglomerate originally subdivided into coarse- and
fine-grained units (Weber and others, 1992). Siltstone and sandstone are
medium- to medium-dark-gray and greenish-gray, moderately sorted and
very fine- to medium-grained. Conglomerate is dark-olive-gray to
medium-dark-gray, iron-stained, polymictic, unsorted, subangular to
well-rounded, ranges in grain size from granules to cobbles. Clasts are
of local derivation and consist of quartzite, limestone, mafic and
felsic igneous rocks, greenstone, diorite and other intrusive rocks,
sandstone, siltstone, phyllite, chert, rare grit, shale rip-ups, and
very rare carbonatite. Beds are typically internally massive, large- to
medium-scale, graded and amalgamated, having planar tops and bases.
Local small-scale trough-crossbeds internally fill large-scale troughs
and fining upward cycles are common. Conglomeratic graywacke occurs
within lenses in unit. Minor small-scale scour-fills locally fine upward
into ripple-laminated medium-gray to black siltstone, and dark-gray to
black shale. Albian age based on presence of *Paragastroplites
flexicostatus*. Graywacke rich in volcanic detritus is locally
characteristic and may correlate with the Kathul Graywacke in the
Charley River quadrangle east of the map area (Dover and Miyaoka, 1988)
(units Kwcc, Kwcs, LG002; unit Kwc, TN003; unit KJgs, KH002; unit KJcs,
KH003) \[symbol 752\] 2115

**Kvgm Volcanic graywacke and mudstone** (Albian)\-- Chiefly
dark-greenish-gray, fine-grained to gritty, poorly sorted turbiditic
graywacke composed largely of first- and second-cycle volcanic debris,
but locally containing abundant granitic and metamorphic rock debris.
Dark-gray mudstone interbeds. Graded bedding common. Contains some
intercalated crystal tuff. Age assignment based on correlation with
similar unit in Hughes quadrangle to north of map area (Patton and
others, 1978). Unit stratigraphically underlies Norton Bay and Melozitna
sequence sedimentary rocks and is thickest in Lower Yukon sub-basin
(Patton and others, 1994a) on west. Unit interpreted as submarine fan
turbidite (W.W. Patton, Jr., oral commun., 1998) \[symbol 983\] 2105
\[*See also unit Kvm, 1825, 2180, 2181*\] unit Kgm, MZ002; unit Knm,
eastern part KT003; unit KJcs, northeastern TN003; unit Kg, NL003)

**Ksm Quartz-carbonate sandstone and pebbly mudstone**
(Valanginian-Aptian)\-- Fine- to coarse-grained quartz-carbonate
sandstone and conglomerate, quartzose limestone, and dark-gray pebbly
mudstone and siltstone. Clast lithologies consist of quartz, carbonate,
and quartz-mica schist. Fossil age control extensive; *Buchia
subleavis*, *B. crassicolis*, and *Cylindroteuthis* in the lower beds,
indicate a Valanginian age, *Inoceramus* and *Arcoteuthis* in middle
beds indicate a Hauterivian and Barremian age, and rare cephalopods
including *Tropaeum* indicate an Aptian age for the upmost beds (Patton
and others, 1980). Unit limited to small areas of outcrop in the Medfra
quadrangle (unit Kqc, MD002) \[symbol 745+13\] 2125

**Knl Nelchina Limestone** (Hauterivian and Barremian)\-- Shallow water
marine sequence of thinly bedded calcareous sandstone, siltstone,
claystone, minor conglomerate, and thick-bedded to massive clastic
limestone, as mapped by Grantz (1960) in the Talkeetna Mountains
quadrangle. The Nelchina Limestone rests with slight angular conformity
on the Late Jurassic Naknek Formation (unit Ksu, TK002) \[symbol
745+13\] 2100

**Kb Berg Creek Formation** (Early Cretaceous?)\-- Marine sandstone,
siltstone, mudstone containing many interbeds of pebble- and
cobble-conglomerate. Greenish-gray sandstone, in many places calcareous
and cross-stratified, is predominant in lower part of the sequence.
Framework grains in the sandstone and conglomerate clasts indicate
largely volcanic source terrain. Dark-greenish-gray siltstone and
mudstone are predominate in the upper part of the section; uppermost
strata include rusty-weathering calcareous siltstone interbeds and
concretions. Originally mapped as unit Js on the Valdez map (Winkler and
others, 1980), according to George Plafker (G.R. Winkler, written
commun., 1998), unit is now considered the lower part of the Berg Creek
Formation (VA002) \[symbol 971\] 2110 (was 3020)

Melange

**KT[r]{.smallcaps}m McHugh Complex** (Cretaceous to Triassic?)\--
Tectonic melange consisting largely of Triassic through mid-Cretaceous
protoliths of oceanic affinity. Blocks are boudins and fault slices of
relatively competent rocks: basalt, chert, graywacke, and conglomerate,
plus rare blueschist, gabbro, ultramafic rocks, and limestone. Matrix
consists of relatively incompetent argillite, and locally, light-green
tuff. Intermixing of blocks in the matrix occurs at scales ranging from
that of a thin section to that of a 1:250,000-scale quadrangle. Gabbro,
basalt, chert, argillite, and graywacke are interpreted as an
oceanic-plate succession conveyed by plate motions into a subduction
zone and deformed into a tectonic melange. Triassic through
mid-Cretaceous radiolaria date the chert, and by inference,
abyssal-plain sedimentation. Limestones, possibly originating on
seamounts, have yielded Permian fusilinids and conodonts of tropical,
Tethyan affinities. The time during which the various protoliths were
intermixed to form a melange is not well constrained, but most likely
spanned the Jurassic and Cretaceous {McHugh Complex of Valdez Group,
melange (unit Mzm, AN002; unit KJm, VA002; unit KJm, TY002) \[symbol
458\] 2190}

**Kmar Melanges of the Alaska Range** (Silurian to Cretaceous
protoliths; Cretaceous melange formation). Consists of four rock suites,
intensely deformed and intricately intermixed by tectonic and perhaps
also sedimentary processes. Suites are: 1) cherty tuff, chert,
argillite, and volcaniclastic sandstone. Radiolaria and conodont
fragments from the Healy quadrangle indicate a Mississippian to Late(?)
Devonian age (Csejtey and others, 1992); 2) flysch-like assemblage of
dark-gray to black argillite, slate, shale, graywacke, and subordinate
chert, chert-pebble conglomerate, and polymict conglomerate. It has
yielded *Buchia* sp. of Late Cretaceous to Late Jurassic age in the
Healy quadrangle (Csejtey and others, 1992), and a Cretaceous ammonite
in the Mt. Hayes quadrangle (Nokleberg and others, 1992b). In the Mt.
Hayes quadrangle, minor andesite and dacite are associated with the
flysch-like assemblage; 3) limestone, of Silurian, Devonian, and
Triassic ages, is mapped and described separately as unit
T[r]{.smallcaps}Sl in the Healy quadrangle; in the Mt. Hayes quadrangle,
limestone is present but not differentiated from the main body of
melange (Nokleberg and others, 1992a); and (4) ultramafic rocks, of
unknown age, mapped and described separately as unit mlu. This melange
unit crops out in two belts in the Healy quadrangle, and two belts in
the Mt. Hayes quadrangle. South of the Denali fault in the Healy
quadrangle, Csejtey and others (1992) mapped the main body of melange as
unit Kms, and limestone blocks within it as unit msl. This southerly
belt of melange corresponds to the Broad Pass terrane of Jones and
others (1982; see fig. 2, herein). Farther north in Healy quadrangle,
Csejtey and others (1992) assigned a narrow belt of melange between two
strands of the Denali fault to their unit Kmn; associated limestone
blocks in this northerly belt were mapped as unit mnl (shown here as
unit T[r]{.smallcaps}Sl), and associated ultramafic rocks were mapped as
unit mno. The northerly belt of melange corresponds to the Windy terrane
of Jones and others (1982). The two belts of melange in Healy quadrangle
are similar in that both contain large proportions of intensely deformed
Kahiltna-like flysch (unit KJf, herein) enclosing blocks of Devonian
shallow-marine limestone; they differ, however, in that ultramafic rocks
and Triassic limestones occur only in the northerly belt, whereas
Paleozoic cherty rocks occur only in the southerly belt. In the Mt.
Hayes quadrangle, Nokleberg and others (1992a) mapped two belts of
melange between strands of the Denali fault system, and correlated these
with the Windy terrane of Jones and others (1982) \[symbol 458\] 2192
2195

**T[r]{.smallcaps}Sl Limestone blocks** (Silurian to Triassic)\-- Lenses
and elongate blocks, up to several kilometers long, of medium-bedded to
rarely massive, fine- to medium-grained, gray, fossiliferous limestone.
Occurs in two outcrop belts in the Healy quadrangle, one south of the
Denali fault, the other between strands of the Denali fault (Csejtey and
others, 1992). Megafossils and conodonts from the southerly belt range
from Silurian to Middle Devonian; megafossils and conodonts from the
northerly belt are of Middle Devonian and Late Triassic ages (Csejtey
and others, 1992). Comparable carbonate blocks occur in two outcrop
belts of melange in Mt. Hayes quadrangle (unit Kmar of present map; unit
wm of Nokleberg and others, 1992a) but were not mapped separately. The
most closely dated of these has yielded a Middle Devonian (Givetian) age
based on megafossils (Nokleberg and others, 1992b) \[symbol 172\] 2193
2196

**mlu Ultramafic and associated rocks** (Unknown age, assigned to
melange)\-- Serpentinized ultramafic rock, altered baslat, green and
maroon tuff and recrystallized chert. Unit occurs in a small fault
sliver within the Denali Fault system in the Healy quadrangle (Csejtey
and others, 1992). Jones and others (1982) suggested these rocks might
comprise an ophiolite assemblage \[symbol 416\] 2197 (unit (mno)Kmn,
HE002)

Igneous rocks\
Volcanic and hypabyssal rocks

**Kvl Volcanic rocks** (Late Cretaceous)\-- Largely dacite, andesite,
and basalt and subordinate andesitic to basaltic subvolcanic rocks.
Ranges from flows, including agglomerate, to tuff and also dikes and
sills; all are variably hydrothermally(?) altered. Subvolcanic rocks are
chiefly found in the southwestern part of the map area, but are also
sparsely distributed in the Healy quadrangle. In the Iditarod quadrangle
these rocks were mapped as part of two units, the Kuskokwim Group and
part of the Iditarod Volcanics. Distinction between unit TKvi of this
map, which also includes the Iditarod Volcanics, is on the basis of the
contact relation between these rocks and the underlying or
interfingering Kuskokwim Group sedimentary rocks. This map unit consists
of those rocks where the interfingering relationship is most apparent
\[symbol 124+14\] 2255, 2256, 2260, 2261, 2270

**Ktg Volcaniclastic rocks** (Early Cretaceous)\-- Largely andesitic and
dacitic crystal-lithic tuff and lithic tuff, volcanic graywacke, and
mudstone. Rare andesite flows. Mapped only along northern edge of
Melozitna quadrangle and in the adjoining Hughes quadrangle outside of
the map area. Overlies unit Kve and may grade laterally into unit Kvgm
\[symbol 124+15\] 2320

**Kve Andesite and related rocks** (Early Cretaceous, Neocomian and
Albian?)\-- Chiefly porphyritic pyroxene andesite and trachyandesite
flows, pillow basalt, andesitic and dacitic tuff, volcanic conglomerate,
and breccia, tuffaceous graywacke, chert and fine-grained cherty tuff,
and limestone, generally restricted to the northwest part of the map
area. In the vicinity of the Koyukuk River these rocks are widely
altered to a hard dark green hornfels near granitic intrusions.
Elsewhere, the volcanic rocks are altered and pale green. Limestone is
in part coquina composed largely of *Buchia* and in part impure
limestone containing *Buchia*. Mildly deformed and unaltered vesicular
basalt and associated pyroclastic rocks along the Koyukuk River near
Roundabout Mt. originally mapped by Patton (1966) as part of this unit
may be Tertiary (Patton, oral commun., 1997) and are shown on this map
as part of unit Tvu. In the Tyonek quadrangle, small areas of basaltic
rocks of probable early Cretaceous age are interbedded within
Cretaceous(?) sedimentary rocks. While included here for display
convenience, we do not mean to imply these Tyonek flows and those near
the Koyukuk River are related \[symbol 124+16\] 2330, 2210 (no
overprint), 2230 (no overprint)

Intrusive rocks

**Kg Granitic rocks**\-- Largely granitic, but range from
tourmaline-bearing granite to diorite. Intrusions range from dikes and
sills, to small and large plutons. Widely distributed includes granite
plutons in the Mount Hayes quadrangle, and quartz monzonite and
granodiorite plutons in the Anchorage, Fairbanks, Livengood, Tanana, and
Melozitna quadrangles. Radiometric ages are as old as 120 Ma and as
young as 70 to 65 Ma, but typically range between 105 and 90 Ma. Plutons
yielding ages of 110 Ma or greater than are shown with a vertical
crosshatch pattern, whereas those yielding ages of 85 Ma or less are
shown with a horizontal crosshatch pattern \[symbol 251\] 2400, 2410,
2411, 2475, 2480, \[+overprint 13\]: 2450, 2460, 2465, 2470,
\[+overprint 14\]: 2520, 2525, 2530, 2540, \[+overprint 238\]: 2420

**Kmum Mafic and ultramafic rocks**\-- Gabbro, diorite, serpentinite,
and mafic volcaniclastic rocks. Ranges from small, structurally bounded,
pervasively sheared, discordant bodies of serpentinized ultramafic rocks
wholly enclosed in pelitic schist in the Anchorage quadrangle (Winkler
(1992) to dikes and lense-like masses of dark-greenish gray, medium- to
coarse-grained gabbro and massive, medium-gray, medium-grained diorite,
including the gabbro of Mount Moffit of the Mount Hayes quadrangle and a
correlative unit of gabbro, diorite, metagabbro, metadiabase, and
amphibolite dikes sills and small plutons (units gbm and mgb, Nokleberg
and others, 1992a). Restricted to bands through the central part of the
map area in the Tanana and Kantishna River, Anchorage, and the Big Delta
and Mount Hayes quadrangles (units gbm, mgb, MH002; unit Kd, BD002; unit
Km?, TN002; unit Km, KH003) \[symbol 672\] 2440, 2445, 2510, 2670

**Ktt Leucotonalite and trondhjemite** (Early Cretaceous)\-- Plugs and
sills of leucocratic medium-grained plutonic rocks in a zone about 5 km
wide along the Border Ranges fault in the Anchorage quadrangle.
Generally foliated; apparently syntectonically emplaced during ductile
and then brittle thrusting on the Border Ranges fault system. K-Ar,
Rb-Sr, and U-Pb age determinations range between 103 and 133 Ma,
overlapping ages of large Jurassic trondhjemite plutons (unit Jtr, this
map) to the north of the Border Ranges fault system (Winkler, 1992)
(AN002; unit Knt, NB002) \[symbol 291\] 2570

Metamorphic rocks

Rocks of unknown protolith age metamorphosed during Cretaceous and
possibly Early Tertiary time.

**Kvs Metasedimentary rocks of the Valdez Group** (Late Cretaceous)\--
Drab, rhythmically alternating, deformed turbidites, including
meta-sandstone, meta-siltstone, argillite, slate, phyllite, and pebble-
to cobble conglomerate. Beds are typically a few centimeters to a few
meters thick. Locally, massive meta-sandstone and less abundant
matrix-supported pebble- to cobble-conglomerate occurs in channel
sequences many tens of meters thick. In some places, turbiditic
sedimentary structures, including graded bedding, current-ripple
cross-lamination, convolute lamination, and sole marks have been
preserved (Winkler, 1992). Adjacent to the thrust contact with McHugh
Complex melange, includes a tectonic melange consisting of blocks of
Valdez Group meta-sandstone enclosed in a phacoidally cleaved matrix of
Valdez Group argillite; this monomict melange is quite distinct from the
polymict melange of the McHugh Complex. Assigned a Late Cretaceous
(Campanian? to Maestrichtian) age on the basis of scattered occurrences
of *Inoceramus*. Mapped in Anchorage and Valdez quadrangles. Metamorphic
grade ranges from prehnite-pumpellyite to lower greenschist facies
\[symbol 745\] 2700

**Kvv Metavolcanic rocks of Valdez Group** (Late Cretaceous)\-- Mafic
metatuff and minor massive or weakly foliated greenstone with rare
pillows (Winkler and others, 1981). Mapped in Valdez and Anchorage
quadrangles. Dated by association with the sedimentary part of the
Valdez Group, with which it is interbedded. Metamorphic grade ranges
from prehnite-pumpellyite to lower greenschist facies \[symbol 311\]
2705

CRETACEOUS AND/OR JURASSIC\
Sedimentary rocks

**KJw Wolverine quartzite** (Early Cretaceous or Late Jurassic)\--
Light- to dark-gray, very fine- to medium-grained, well-sorted,
quartzite containing interbedded black to dark-gray shale and
medium-light- to medium-gray siltstone. Rare coquina-like beds contain
poorly preserved fragments of *Buchia* and other fossils that provide
limited age control. Unit exposed in the Livengood, western Circle, and
eastern Tanana quadrangles. In the Tanana quadrangle, the Wolverine
quartzite includes rocks mapped as the Vrain unit (KJvr) elsewhere (F.R.
Weber, unpublished data, 1998) (LG002; unit KJcs, TN002; TN003; unit
KJw, TN003; unit KJqa, CI002) \[symbol 909\] 2815, 2816, 2817

**KJwc Wilber Creek flysch and Wolverine quartzite, undivided** (Early
Cretaceous or Late Jurassic)\-- Locally mapped unit consisting of units
KJwc and Kwcf in the Tanana quadrangle (TN003 modified, shown as
southern T[r]{.smallcaps}Ps) \[symbol 909+13\] 2812

**KJs Argillite, chert, sandstone, and limestone** (Early Cretaceous to
Late Jurassic)\-- Dark-gray argillite, dark-gray to greenish-gray bedded
chert, thin-bedded gray sandstone, and rare thin-beds of shelly
limestone in thrust slivers, sandwiched between Triassic and Jurassic
strata in the southwest Healy quadrangle. Late Jurassic and Early
Cretaceous radiolaria occur in the chert; *Inoceramus sp.* of
Hauterivian to Barremian age and *Buchia subleavis* of Valanginian age
occur in the limestone. Csejtey and others (1992) suggest these rocks
may be tectonically emplaced distal facies of unit KJf. Metamorphic
grade in these rocks is no higher than prehnite-pumpellyite facies,
significantly lower metamorphic grade than rocks of unit KJf (as mapped
by Csejtey and others, 1992) to the east (unit KJa, HE002) \[symbol
909+14\] 2810.

**KJf Kahiltna flysch sequence** (earliest Late Cretaceous to Late
Jurassic?)\-- Monotonous sequence of intensely deformed and locally
highly metamorphosed turbidites described by Csejtey and others (1992)
and Reed and Nelson (1980). Includes dark-gray to black argillite, fine-
to coarse-grained, generally dark-gray graywacke, dark-gray polymictic
pebble conglomerate, subordinate black chert pebble conglomerate, a few
thin layers of dark-gray to black radiolarian chert and thin, dark-gray
impure limestone interbeds. Locally includes distinctively reddish brown
weathering feldspathic wacke having interbeds of siltstone. Tightly
isoclinally folded and complexly faulted. Highly indurated, many are
sheared and pervasively cleaved. Fossils in this broadly defined unit
range from Early Jurassic ammonites to Early Cretaceous (late
Hauterivian to early Barremian) *Inoceramus* to indeterminate broadleaf
plant fossils. In the Tyonek quadrangle, a Valanginian *Buchia sublaevis
Keyserling* was identified from coquina beds along the lower Chickak
River (William P. Elder, USGS, unpublished data; fossil collection by
Madelyn Millholland, Cominco Alaska Exploration). A middle Turonian
*Inoceramus hobetsensis Nagao* and *Matsumoto* was also found within
this unit 1 km east of the Skwentna River 3 km north of its confluence
with Emerald Creek (William P. Elder, USGS, unpublished data, 1989).
Reported plant fossils occur in rocks lithologically similar to the
largely Late Cretaceous Matanuska Formation (unit Km, this map).
Previously unpublished 40Ar/39Ar age determinations on hornblende in
igneous clasts in conglomerate range from 94.6+/-1.5 Ma to 101.0+/-0.7
Ma (Paul Layer, written commun., Sept., 1997; see also Layer and Solie,
1991). In the Talkeetna quadrangle, unit is mapped as Jurassic and
Cretaceous. However, the only fossil localities having Jurassic ages are
at the northwestern extent of the outcrop area and all other ages were
considered Cretaceous. This unit, widespread in southern Alaska, is
often the repository for miscellaneous dark-colored sedimentary rock
units and as such may not represent a coherent package of rocks. In the
southwest part of the map area, the nature of the transition from this
unit to the Kuskokwim Group is undefined. Both units are of similar
lithology and character and available mapping is not sufficient to
either distinguish the units or to indicate that they should be mapped
as the same unit. Locally, the presence of interbedded light tuffaceous
deposits indicates contemporaneous volcanism; in these same areas,
extremely angular grains of oscillatory zoned plagioclase, volcanic rock
fragments, hornblende, epidote, and calcite, suggest derivation from the
now buried Jurassic magmatic arc to the south (Reed and Nelson, 1980).
Unit as mapped in the Tyonek quadrangle includes rocks mapped by Reed
and Elliott (1970) as units Km, Kw, Mzu, and Mzs. In the southeastern
part of the Healy quadrangle, east of the Susitna lineament of Smith and
others (1984) this unit is highly metamorphosed and included within
rocks mapped as part of the Maclaren metamorphic belt (units Mzsa and
Mzpca), of mid-Cretaceous age (Csejtey and others, 1992) or Tertiary age
(Smith, 1981). The Kahiltna flysch unit is sub-divided on this map into
three sections. The two sub-divisions off the main part of the unit
consist of unit KJfn, occurring north of the main strand of the Denali
fault system, and unit KJfk, which is found in a klippe south of the
Denali fault system. Locally subdivided into: (unit KJfk, HE002)
\[symbol 793+13\] 2851

**KJfk Flysch sequence** (Early Cretaceous and Late Jurassic)\-- Rocks
identical in lithology and age to unit KJf, found in a large folded
klippe or thrust sliver that may be as large as 30 by 60 km, perhaps a
remnant of a much larger thrust sheet (Csejtey and others, 1992). There
are three fossil localities within this unit, two of which have yielded
Valanginian *Buchia* fossils and one yielding Jurassic or Cretaceous
radiolaria

**KJfn Flysch sequence** (Late Cretaceous and Late Jurassic)\-- Rocks
identical in lithology and age to unit KJf, found north of the main
strand of the Denali fault system. Reed and Nelson (1980) were uncertain
about assigning a Jurassic age as no Jurassic age fossils have been
found in the unit in the Talkeetna quadrangle. In general, these rocks
are not adjacent to those of unit KJf south of the fault system. May
represent a separate part of the flysch depositional basin or a separate
fault-juxtaposed basin

**KJfm Metasedimentary rocks** (Early Cretaceous and Late Jurassic)\--
Principally deep-marine turbidite deposits consisting of graded beds of
metamorphosed dark-gray to gray argillite, siltstone, and graywacke that
locally alternate with beds of massive graywacke, pebbly graywacke,
pebble to cobble conglomerate and sparse andesite flows(?) or sills(?)
in the Mount Hayes quadrangle (Nokleberg and others, 1992a). Unit is
thought to constitute a part of the Gravina-Nuzotin belt (Berg and
others, 1972, cited in Nokleberg and others, 1992a) which extends to the
southeast

**KJcg Conglomerate, sandstone, siltstone, shale, and volcanic rocks**
(Early Cretaceous and Late Jurassic)\-- Intercalated polymictic pebble
and cobble conglomerate, sandstone, siltstone, shale, and flows and
dikes of andesitic and latitic feldspar porphyry (Csejtey and others,
1992). In two thrust slivers along the Talkeetna thrust fault in the
southeastern part of the Healy quadrangle and the northeastern part of
the Talkeetna Mountains quadrangle. Locally strongly sheared, displaying
shear planes that cut conglomerate clasts. Age based on collections of
*Buchia spp.* of Late Jurassic to Early Cretaceous age in the Healy
quadrangle (Csejtey and others, 1992) and *Buchia Rugosa*, suggesting a
Kimmeridgian age in the adjacent Talkeetna Mountains quadrangle (Csejtey
and others, 1978). Csejtey and others (1992) suggest these rocks were
probably deposited at the base of the continental slope as part of
submarine fan sequence and that they may constitute the westernmost
outcrops of the Gravina-Nuzotin belt of Berg and others (1972) (HE002)
\[symbol 793+15\] 2821

**KJvr Vrain unit** (Early Cretaceous and (or) Jurassic)\-- Dark-gray to
black, pyritiferous shaly slate, or black fissile shale and minor
medium- to dark-gray, olive- or greenish-gray siltstone. Closely
resembles upper part of the Glenn Shale in the Nation River area in the
eastern Charley River quadrangle (east of the map area). Crops out in
northeast and southwest parts of the Livengood quadrangle (Weber and
others, 1992) and northwestern part of the Circle quadrangle (F.R.
Weber, unpublished data, 1998). Unit is thought to continue into the
Tanana quadrangle, however mapping there did not separate it from the
Wolverine quartzite. As shown here, also includes unit MzPzp of the
Livengood quadrangle (Weber and others, 1992), possibly a more highly
metamorphosed and tectonically disrupted equivalent unit (unit KJv,
LG002; part of unit MzPzat, CI002) \[symbol 909+16\] 2860, 5216

Intrusive rocks

**KJg Granitic rocks** (Early Cretaceous or Jurassic)\-- Consists of
granitic rocks ranging from granite to quartz diorite and including
minor monzonite and diorite. Restricted to the Mount Hayes and Gulkana
quadrangles south of the Denali fault system, although widely
distributed in these quadrangles. Generally in small stocks, dikes, and
sills. Granite porphyry of Caribou Lake (unit grcl, Nokleberg and
others, 1992a) has outcrop exposures as much as 5 km in area. The age of
many of these intrusive bodies is inferred, however several of the
plutons have been dated as Early Cretaceous and Late Jurassic (Nokleberg
and others, 1992a) (unit grcl, grs1, grs2, grs3, MH002; units Kgd, hbqd,
hbqm, hbgd, GU002) \[symbol 248\] 2900

Metamorphic rocks

**KJhc Haley Creek metaplutonic and metasedimentary rocks** (Early
Cretaceous to Late Jurassic)\-- Metaplutonic rocks predominantly diorite
and quartz diorite, but range from trondjemite to hornblende gabbro and
hornblendite; metasedimentary rocks include schistose marble, pelite,
and meta-arenite. Plutonic and sedimentary protoliths vary in relative
abundance from place to place. Subjected to two metamorphic events, an
earlier epidote-amphibolite event and a pervasive greenschist event that
produced the predominant metamorphic and cataclastic fabrics. Four K-Ar
ages of hornblende from metaplutonic rocks range from 148 to 122 Ma;
K-Ar ages of biotite from metasedimentary rocks are 123, 110, and 50 Ma
(Winkler and others, 1980). Protolith previously correlated with the
Skolai Group by MacKevett and Plafker (1974), but the unit is
fault-bounded and may be unrelated to juxtaposed units. Includes the Khc
and Kag units of MacKevett and Plafker (1974) (unit Khc, VA002) \[symbol
455\] 2601, 2600 (unit ag, MH002; unit Kag, Haley Creek terrane,
metaplutonic rocks VA002) \[symbol 455\] 2600

JURASSIC\
Sedimentary rocks

**Jn Naknek Formation** (Late Jurassic)\-- Thin- to thick-bedded,
intercalated fossiliferous gray siltstone, shale, sandstone, and
conglomerate more than 1,400-m-thick (Csejtey and others, 1978).
Originally named Naknek Series by Spurr (1900, p. 169-171, 179, 181) for
exposures at Naknek Lake on the Alaska Peninsula. Megafossils,
particularly the pelecypod *Buchia* (Detterman and Reed, 1980, p. B-38;
J.W. Miller, written commun., 1982-88), are common, and the fauna, which
also includes ammonites, indicates age range of Oxfordian to late
Tithonian. The Jurassic Alaska-Aleutian Range batholith was a major
sediment source for the Naknek Formation; hence, uplift and erosion of
the batholith occurred shortly after emplacement. The unit mapped here
is probably correlative with the Indecision Creek and possibly Katolinat
Conglomerate Members on the Alaska Peninsula (see Detterman and others,
1996) and therefore represents the upper part of the unit. Correlation
has been suggested with the Root Glacier Formation of the Wrangell
Mountains, east of the map area (E.M. MacKevett, in Csejtey and others,
1978) (B-1969A; AN002; TK002) \[symbol 844\] 3010

**Jct Chinitna Formation, Tuxedni Group, and coeval sedimentary rocks**
(Late and Middle Jurassic)\-- Largely shallow-marine clastic rocks
ranging from shale and siltstone to conglomerate. All rock units contain
a mixture of plutonic and volcanic detritus and clasts that are presumed
to have been derived from erosion of the Talkeetna Formation and related
plutonic rocks of the early Jurassic magmatic arc. Overlies the
Talkeetna Formation with angular uniformity. Internal contacts between
stratigraphic units in this package are disconformities or slight
angular unconformities. The uppermost part of this map unit, the
Chinitna Formation, is disconformably or with slight angular
unconformity overlain by the Naknek Formation. Restricted to the
southern tier of quadrangles in the map area; widely distributed in the
Valdez, Anchorage, Talkeetna Mountains, and Tyonek quadrangles. The same
and correlative rock units are especially well-exposed on the Alaska
Peninsula to the southwest (Detterman and others, 1996). Locally
sub-divided into: (unit Jct, TK002; units Jc, Jt, AN002; units Js, Jkt,
VA002) \[symbol 841\] 3140

**Jc Chinitna Formation** (Middle Jurassic, late Bathonian(?) and early
and middle Callovian)\-- Shallow-marine shale, siltstone, and
subordinate sandstone containing numerous large limestone concretions.
Contains mixture of plutonic and volcanic detritus presumed to have been
derived from erosion of the Talkeetna Formation and related plutonic
rocks of the early Jurassic magmatic arc. Correlative with Shelikof
Formation of the Alaska Peninsula (Detterman and others, 1996). Unit
mapped only in the Anchorage quadrangle, south of the Castle Mountain
fault system (AN002) \[symbol 971\] 3030

**Jkt Kotsina Conglomerate** (Middle and/or Late Jurassic?)\-- Thin- to
thick-bedded, well-indurated conglomerate containing locally derived
pebbles and cobbles and subordinate sandstone and shale. Reflects rapid
local marine deposition in response to Middle Jurassic orogenesis.
Restricted to the Valdez and adjacent McCarthy quadrangles; correlative
rocks occur in the upper part of the Tuxedni Group and the Bowser
Formation to the west. No fossils are known; age inferred from K-Ar age
determinations on dikes that cut the unit (VA002; unit Jk, MC002)
\[symbol 841\] 3110

**Jtx Tuxedni Group** (Middle Jurassic, Bajocian-Bathonian)\--
Fossiliferous shallow-marine siltstone, shale, and sandstone. Upper part
is thin- to thick-bedded dark siltstone and shale; lower part consists
of thin- to thick-bedded sandstone and local pebbly sandstone.
Unconformably overlies the Talkeetna Formation and is disconformably
overlain by the Chinitna Formation. Unit crops out only in the Anchorage
quadrangle (Winkler, 1992), where it is much thinner than in areas to
the southwest, where divided into three Formations (unit Jt, AN002)
\[symbol 971\] 3180

Igneous rocks

**Jmu Mafic and ultramafic rocks** (Jurassic?)\-- Various mafic and
ultramafic rocks, widely distributed chiefly in the southern part of the
map area:\
\
In the Valdez quadrangle (Winkler and others, 1980), dunite,
harzburgitic dunite, wehrlite, websterite, and clinopyroxenite outcrop
in a discontinuous belt 25 km long, locally called the Tonsina
ultramafic complex. A complex largely of layered hornblende-pyroxene
gabbro, leucogabbro, gabbronorite as much as 120 km long and 10 km wide
also occurs in the Valdez quadrangle and in the adjacent Anchorage
quadrangle north of or within the Border Ranges fault zone. Radiometric
age determinations (Winkler and others, 1980; Winkler, 1992) suggest an
Early and Middle Jurassic age.\
\
In the Anchorage quadrangle, fault-bounded cumulate ultramafic and mafic
rocks of the Wolverine and Eklutna complexes of Winkler (1992) have an
inferred age of Middle and Early Jurassic based on correlation with the
Tonsina complex of the adjacent Valdez quadrangle and intrusion by
Middle and Early Jurassic dikes (Winkler, 1992).\
\
In the southeastern Healy quadrangle, a small discordant pluton of
alkali gabbro (monzogabbro) and similar rocks have an inferred age of
Late Jurassic (Csejtey and others, 1992). In addition, a small body of
dark greenish- or brownish-gray, coarse- to medium-grained ultramafic
rock containing olivine and abundant phlogopite, limited to an area
between the Denali and Hines Creek strands of the Denali fault system
was inferred by Csejtey and others (1992) to be Early Cretaceous or
Jurassic in age. It appears to intrude late Triassic calcareous rocks of
unit T[r]{.smallcaps}cs and been metamorphosed a middle Cretaceous
regional event which affected rocks in the eastern Healy quadrangle.\
\
In the McGrath quadrangle, a series of gabbro and diorite sills intrudes
late Paleozoic chert and volcaniclastic rocks and late Triassic
limestone and have an inferred Early Cretaceous or Jurassic age.\
\
Found throughout the northwestern Gulkana quadrangle, schistose
hornblende and clinopyroxene gabbro (Nokleberg and others, in press,
units scgb and shgb), even though metamorphosed to greenschist facies is
included in this unit (units Ju, Jmp, Jgl, Jum, Jtu, VA002; units Jmip,
Jg, Jgs, Jum, AN002; unit Jm, TY002; unit Jgb, HE002; units shgb, scgb,
GU002; unit Jpmu, TK002) \[symbol 633\] 3340, 3345, 3346, 3350, 3390,
3405, 3490, 3491, 3495, 3540, 3545 \[symbol 365\] 2920, 2945 \[*Consider
lumping with units 4320, 4321, unit Trgb in MH quad.*\]

**Jtr Trondhjemite** (latest Jurassic)\-- Altered, sheared, and locally
faintly foliated trondhjemite in large, structurally discordant,
northeast-trending plutons intruding Jurassic quartz-diorite and
amphibolite (Winkler, 1992). Plutons crop out in the Talkeetna Mountains
and Anchorage quadrangles. K-Ar age determinations range from 129 to 149
Ma, which overlap ages of Cretaceous trondhjemite (unit Ktt) to the
south (AN002; TK002) \[symbol 291+13\] 3380

**Ji Alaska-Aleutian Range and Chitina Valley batholiths,
undifferentiated** (Late and Middle Jurassic)\-- Includes Jurassic phase
of the Alaska-Aleutian Range batholith (Reed and Lanphere, 1972) and the
Jurassic Chitina Valley batholith in the Valdez quadrangle (Winkler and
others (1980). Ranges from granite through granodiorite to quartz
diorite and tonalite. Widely distributed in southern Alaska. Probably
the plutonic equivalent of volcanic rocks of Talkeetna Formation,
usually found in close proximity to the Talkeetna Formation. The
Alaska-Aleutian Range batholith has been best described and dated by
Reed and Lanphere (1969, 1972, 1973) \[symbol 312\] 3400, 3401, 3402,
3403, 3404 (units Ji, Jgd, VA002; units Jg, Jgd, TY002; units Jgd, Jqd,
TK002; units Jgd, Jqd, Jqt, AN002)

Metamorphic rocks

(All ages quoted for these units are metamorphic ages\
and do not necessary reflect the protolith)

**Jsch Greenschist and blueschist** (Jurassic)\-- Diverse well-foliated,
multiply-deformed metasedimentary and metavolcanic rocks of greenschist
and transitional blueschist facies diverse mafic metavolcanic and
metasedimentary rocks. Sedimentary protoliths are shale, chert,
tuffaceous arenite, and limestone; volcanic protoliths are probably
mostly basalt (Winkler, 1992). Outcrop along the northern flank of the
Chugach Mountains in the Anchorage and Valdez quadrangles, closely
associated with the Border Ranges fault system. In the Valdez
quadrangle, includes the schist of Liberty Creek (G.R. Winkler, written
commun., 1998). In the Anchorage quadrangle, includes the Knik River
schist (unit JPzm of Winkler, 1992 or Knik River terrane of Pavlis,
1983; Pavlis and others, 1988) and is correlative with the other
schistose units along the Border Ranges Fault system to the southwest,
including the Raspberry Schist of Roeske and others (1989) of the Kodiak
Islands and the Seldovia Schist of Roeske (1986, see also Cowan and
Boss, 1978). Age control is limited, isotopic ages from metamorphic
minerals indicate an Early Jurassic age of metamorphism (see Winkler,
1992; Carden and others, 1977) and Clark (1972, cited in Winkler, 1992)
reports a single Permian fossil collection from limestone. The
correlative Raspberry Schist of Roeske and others (1989) is intruded by
the Triassic Afognak pluton. By analogy with the lithologically similar
Strelna (unit PPast, this map), Winkler (1992) suggested some parts of
this unit may be as old as middle Paleozoic. Locally, these rocks are
included in the McHugh Complex melange. Winkler (1992) suggested that
the diverse of protolith lithologies may indicate tectonic mixing prior
to metamorphism Change label to Jbm at some point (was unit Klc, now
Jlc, also unit Jgb, VA002) \[symbol 963\] 3610 5200

**Jps Pelitic schist** (Jurassic?)\-- Quartz-muscovite-albite-chlorite
schist. Schist remarkably uniform in lithology and has no known
correlative rocks (Winkler, 1992). Mineralogy indicates greenschist
metamorphism, which Winkler (1992) interpreted probably was retrograded
from amphibolite facies metamorphism. Jurassic age inferred for prograde
metamorphism based on the age of adjacent amphibolite of unit Jma. K-Ar
muscovite ages of 66 to 51 Ma from schist are thought to reflect
intrusion of adjacent tonalite and quartz monzonite. Corresponds to unit
Jps of Winkler (1992) in Anchorage quadrangle, and unit MzPzs, schist at
Willow Creek, of Magoon and others (1976) \[symbol 772\] 3700

**JPaur Uranatina metaplutonic complex** (Jurassic and Pennsylvanian)\--
Schistose quartz diorite, quartz monzonite, granodiorite, hornblende
diorite, amphibolite, and orthogneiss forming a belt across the
northeastern Valdez, Gulkana and northeastern Talkeetna Mountains
quadrangle in the southern part of the map area. Unit also forms the
core of a tectonic inclusion in the McHugh Complex in the east-central
part of the Valdez quadrangle. Mainly of upper greenschist facies
metamorphic grade, some parts of unit reach amphibolite facies.
Nokleberg and others (in press) report numerous Jurassic K-Ar ages for
these metaplutonic rocks and interpret these to indicate the time of
metamorphism. In the Valdez quadrangle (Plafker and others, 1992) report
a Pennsylvanian U-Pb zircon age of 309+/-11 Ma on blastomylonitic
granodiorite, interpreted as an emplacement age for at least part of the
complex. However metadiorite yielded a Late Jurassic U-Pb zircon age of
153+/-4 Ma, also thought to indicate emplacement. Includes units sqd,
sgd, sqm, and ag in the Gulkana quadrangle of the Metamorphic complex of
Gulkana River (Nokleberg and others, in press) and units Jlg and Jag in
the Valdez quadrangle (Winkler and others, 1980; G.R. Winkler, written
commun., 1998) \[symbol 573\] 5245 units Jlg, Jag, VA002 \[Changed per
Winkler, 1998; units sqm, sqd, sgd, shd, and ag GU002

JURASSIC AND TRIASSIC\
Sedimentary rocks

**JT[r]{.smallcaps}lm Limestone and marble** (Early Jurassic or Late
Triassic?)\-- Light- to dark-gray, fine to medium-grained, massive to
poorly bedded, unfossiliferous limestone in discontinuous lenticular
bodies within the Talkeetna Formation. Individual lenses as much as 30 m
thick. Near intrusions, recrystallized to marble (see unit Jmb) (unit
Jls, TK002; unit Trl, AN002) \[symbol 977\] 4031

**JT[r]{.smallcaps}mc McCarthy Formation** (Early Jurassic and Late
Triassic)\-- Upper member dominantly thin-bedded, very fine-grained
spiculite, impure chert, impure limestone, and shale; lower member
characteristically thin-bedded impure limestone, calcareous carbonaceous
shale and impure, locally spiculitic chert (MacKevett, 1978). Fossils in
upper member indicate an Early Jurassic age, from Hettangian to
Plensbachian, by inference, the lower unfossiliferous parts of the upper
member may be as old as latest Triassic. Fossils, *Monotis sp.*, from
the lower part of the lower member indicate a Late Triassic, mainly late
Norian, age and MacKevett (1978) suggested that post-Norian Late
Triassic and Early Jurassic rocks might be present also. Unit as a whole
is marine and the depositional character indicates a restricted
environment and possibly starved basin (unit JTrm, MH002; MC002; unit
JTrm, VA002) \[symbol 912\] 3820, 3821

Igneous rocks

**JT[r]{.smallcaps}tk Talkeetna Formation** (Early Jurassic, Late
Triassic?)\-- Greenstone and tuff first described by Paige and Knopf
(1907); the name Talkeetna Formation introduced by Martin (1926),
recognized as widespread and an important marker horizon in southern
Alaska. Varies from volcanic and volcaniclastic rocks consisting of
lava, agglomerate, breccia, tuff, and interbedded sandstone and shale in
the Cook Inlet region to volcanic-sourced sedimentary rocks more distal
from volcanic sources. Unit is the extrusive product of an early
Jurassic island arc, of which the Jurassic phase of the Alaska-Aleutian
Range batholith (unit Ji) is the plutonic core. Shallow marine and
subaerial deposition for much of the unit is apparent from its fossil
content and sedimentary facies (Winkler, 1992). An early Jurassic age is
well accepted for the unit, however based on correlation with the
Pogibshi unit of Kelley (1984) on the southern Kenai Peninsula, Winkler
(1992) inferred a Late Triassic age for the basal part of the unit.
Lenticular limestone and marble bodies are interstratified with the
volcanic and volcaniclastic rocks and are mapped separately as unit
JT[r]{.smallcaps}lm and part of Jmb (TK002; unit JTrt, AN002; unit Jtk,
VA002; TY002; unit Mzv, TY003; TY005; units Jta, Jts, Jtrd, GU002)
\[symbol 790\] 3250

TRIASSIC\
Sedimentary rocks

**T[r]{.smallcaps}ls Chitistone and Nizina Limestones, undivided** (Late
Triassic, Norian to Karnian)\-- Carbonate rocks that overlie the Nikolai
Greenstone (unit Trn) are generally assigned to these two units
(MacKevett, 1978). The Chitistone Limestone at the base is up to
600-m-thick and has a lower part consisting of abundant dolostone,
algal-mat chips, stromatolites, and relicts of evaporites, whereas the
upper part consists of diverse types of limestone including lime
mudstone, wackestone, packstone, and grainstone. The overlying Nizina
Limestone is as much as 500-m-thick and consists of various types of
limestone that generally contain subordinate chert as nodules, lenses,
and coalescing masses; it is gradational lithologically into the
overlying McCarthy Formation. Along with the Nikolai Greenstone, these
limestone units are critical parts of the Wrangellia terrane as defined
(Jones and others, 1977). These limestones, correlative unnamed units in
the Mount Hayes and Healy quadrangles, and the Kamishak Formation to the
southwest are widespread in southern Alaska (unit Trcn, HE002; MC002;
unit Trl, VA002; unit Trl, MH002; NB002; unit Trm, MC002 \[symbol 977\]
4030

**T[r]{.smallcaps}sl Spiculite and sandy limestone** (Late Triassic,
Norian)\-- Dark-gray banded spiculite and chert,
yellowish-orange-weathering sandy fossiliferous limestone and
conglomerate and dark-gray shale in the Medfra quadrangle (Patton and
others, 1980). Lithologically similar to and correlative with the lower
part of the McCarthy Formation (unit JT[r]{.smallcaps}mc) in the
southeast part of the map area, however it is unlikely that these units
were deposited in the same basin (unit Trs, MD002) \[symbol 841\] 4032

**T[r]{.smallcaps}cs Calcareous sedimentary rocks** (Late Triassic,
middle? Norian and Late Karnian)\-- Thin-bedded, dark- to medium-gray
commonly cross-bedded, and carbonaceous intercalated calcareous shale,
argillite, sandstone, siltstone, and sandy to silty and argillaceous
limestone; generally intensely deformed. Basal beds predominantly
fine-grained, gray sandstone and siltstone and subordinate cherty
limestone containing black chert clasts (Bundtzen and others, 1997a).
Age established by conodonts *Negondolella polynathiformis* and
*Epigondolella primitia* and the occurrence of the pelecypod *Monotis*
cf. *M. subcircularis* as reported in Csejtey and others (1992) and
Bundtzen and others (1997a). Extensively exposed both north and south of
the McKinley strand of the Denali fault system. Distinguished from other
Late Triassic carbonate units, such as the Chitistone and Nizina
Limestone by turbiditic depositional character, lack of evaporitic or
sahbka facies rocks, inclusion of clastic debris, and intense
deformation. Rocks in eastern and southern exposures are metamorphosed
to greenschist and amphibolite facies in the MacLaren metamorphic belt
of Smith (1974) and we tentatively include unit sq of the MacLaren
terrane of Nokleberg and others (1992a) in this unit. Metamorphosed
sedimentary rocks in the Mount Hayes quadrangle of the Aurora Peak
terrane of Nokleberg and others (1992a, unit as) were tentatively
correlated with these rocks and are shown as such here. Associated with
this unit are large dikes, sills, and plugs of altered diabase and
gabbro (HE002; MM002; unit as, sq, MH002; unit Trls, MG002) \[symbol
937\] 4033, 5201, 5207

**T[r]{.smallcaps}cg Conglomerate and volcanic sandstone** (Late
Triassic, Norian)\-- Mapped only in a fault bounded(?) exposure at Broad
Pass, just south of the Denali fault zone (Csejtey and others, 1992) in
the Healy quadrangle. The lower part of this section consists of cobble
to boulder conglomerate containing clasts of green volcanic rocks and
red radiolarian chert. The chert clasts have yielded Permian radiolaria.
Finer grained volcanogenic conglomerate, higher in the section locally
contains abundant *Heterastridium* sp., indicating a Late Triassic, late
Norian age. The uppermost part of the section is massive volcanic
sandstone. No Permian source area is known for the chert of this unit
and its overall lithologic character is unique for the Healy quadrangle
(HE002; unit Trs, MG002) \[symbol 937+13\] 4050

**T[r]{.smallcaps}ps Phosphatic shale and limestone** (Triassic?)\--
Thinly bedded, medium- to dark-gray, locally calcareous, phyllitic, and
graphitic, phosphatic shale, medium-gray micritic limestone, and
medium-dark- to dark-gray packstone having sand- or silt-sized quartz
and sparite. These lithologies grade into medium-gray calcareous
sandstone and medium-light-gray phosphatic granule conglomerate (Weber
and others, 1992). Triassic to Permian microfossils constrain the age
and Weber and others (1992) infer a Triassic age because of similarities
to the Glenn Shale (Brabb, 1969) of the Charley River quadrangle to the
northeast of the map area (unit Trs, LG002) \[symbol 973\] 4080

**T[r]{.smallcaps}sc Black shale and chert** (Triassic)\-- Interlayered
black shale or slate, light, olive-greenish-gray thinly bedded to
massive and thickly bedded radiolarian-bearing chert, and light
greenish-gray tuff (Weber and others, 1992). Mapped only in Livengood
quadrangle. In Tanana quadrangle, equivalent rocks are part of undivided
unit TrPs (unit Trc, LG002) \[symbol 841\] 4110

Igneous rocks\
Volcanic rocks

**T[r]{.smallcaps}n Nikolai Greenstone and related rocks** (Late and/or
Middle Triassic)\-- Massive, dark-gray-green, dark-gray-brown, and
maroon-gray subaerial and submarine basalt flows and minor interbedded
volcaniclastic sedimentary rocks, aquagene and epiclastic tuff, breccia,
argillite, and radiolarian chert (Nokleberg and others, 1992a). Widely
distributed and several thousands of meters thick. Commonly associated
with Late Triassic carbonate and cherty carbonate rocks. Together with
the Chitistone and Nizina Limestones, this unit is one of the diagnostic
units of the Wrangellia terrane (Jones and others, 1977). Commonly
metamorphosed to lower greenschist facies. Similar or correlative units
include the Cottonwood Bay Greenstone of the Lime Hills quadrangle (Reed
and Gamble, 1988; Gamble and Reed, 1996) and unnamed Triassic greenstone
units in the Talkeetna Mountains (Csejtey and others, 1978), Healy
(Csejtey and others, 1992), and Mount McKinley quadrangles (Bela
Csejtey, Jr., written commun., 1993) and the Livengood (Weber and
others, 1992) and Kantishna River (Chapman and others, 1975) quadrangles
(HE002; VA002; MH002; GU002; units Trnf; Trnp, MH002) (unit Trbd, HE002;
MM002) (unit MzPzg, LH002; unit Trm, TY002) (unit Trv, TK002) (unit Trm,
LG002; KH002; unit Trb, LH003) \[symbol 375\] 4420, 4421, 4422, 4423,
4425, 4430, 4210

Plutonic rocks

**Trc Carbonatite** (Triassic)\-- Intensely magnetic
dolomite-calcite-magnetite-apatite-rich rock in two sill-like bodies in
the southeastern Tanana quadrangle. 40Ar/39Ar age of about 200 Ma
reported on contact metamorphic mica reported by Reifenstuhl and others
(1998) and interpreted as an intrusion age (units ga and cu, MH002; unit
Trg, MC002; unit Trum, MG002; units Trg, Trcg, GU002) \[symbol 640\]
4320, 4321

**T[r]{.smallcaps}gb Gabbro, diabase, and metagabbro** (Late
Triassic?)\-- Chiefly hornblende-, clinopyroxene-, and
hornblende-clinopyroxene-gabbro and sparse quartz gabbro and quartz
diorite, along with other mafic and ultramafic rocks. Possible source of
flows in the Nikolai Greenstone and related units

Metamorphic rocks

**T[r]{.smallcaps}nm Metavolcanic and associated metasedimentary rocks**
(Late Triassic)\-- Dominantly metabasalt, slate, and other low-grade
metasedimentary and metavolcaniclastic rocks; probably derived from the
Nikolai Greenstone (Trn unit) of contiguous areas. Corresponds to the
T[r]{.smallcaps}vs unit of Csejtey and others (1992) in the Healy
quadrangle, the T[r]{.smallcaps}vs unit of Csejtey and others (1978) in
the Talkeetna Mountains quadrangle, and the csv unit of Nokleberg and
others (1992a) in the Mount Hayes quadrangle (unit csv, MH002; unit
JTrs, NB002; unit Trvs, HE002; unit Trvs, TK002) \[symbol 372\] 4410,
4450, 4440

MESOZOIC AND PALEOZOIC\
Assemblages and Sequences

The **Chulitna sequence**, consists of disparate thrust-imbricated
sequences or assemblages ranging in age from Cretaceous to Devonian
(Csejtey and others, 1992). Gravity measurements by R.L. Morin (Csejtey
and others, 1992, p. 31) indicate that these are rootless thrust sheets.
The Chulitna sequence crops out in the southwestern part of the Healy
quadrangle, southeastern Mount McKinley quadrangle, and the northeastern
extreme of the Talkeetna quadrangle. Csejtey and others (1992) indicate
that these rocks are dissimilar in lithology, depositional environment,
and age from surrounding units and suggest that they are tectonically
emplaced remnants of deep oceanic sedimentary units. Units of the
Chulitna sequence include the following:

**JT[r]{.smallcaps}su Red and brown sedimentary rocks and basalt**
(Early Jurassic and Late Triassic)\-- Red-bed sequence of sandstone,
siltstone, argillite, and conglomerate grading upward into highly
fossiliferous brown sandstone and brownish-gray siltstone. Thickness
more than 2,000 m. Red-bed sequence contains a few thin interbeds of
brown fossiliferous sandstone, pink to light-gray dense limestone, and
intercalated basalt flows. Clasts in the red-beds are dominantly basalt
cobbles and pebbles derived from underlying basalt and from flows within
the sequence. Quartzite pebbles and flakes of white mica and red
radiolarian chert pebbles and grains are present in subordinate amounts.
Fossils indicate a Late Triassic and Early Jurassic age. Mapped only in
the Healy quadrangle; on strike southwest of Eldridge Glacier in the
Talkeetna quadrangle is replaced by light-green to maroon volcaniclastic
rocks of Late Triassic age (see unit JT[r]{.smallcaps}ct, below)
\[symbol 838\] 3830 (unit JTrrs, HE002)

**JT[r]{.smallcaps}ct Crystal tuff, argillite, chert, graywacke, and
limestone** (Late Jurassic to Late Triassic?)\-- Moderately deep to deep
marine sequence of tightly folded and internally faulted tuff and other
rocks at least several thousand meters thick; tuff constitutes about 80
percent of the sequence. Mapped in southwest Healy and northwest
Talkeetna Mountains quadrangles. Csejtey and others (1992) indicate that
the argillite, chert, graywacke, and limestone occur only in a narrow
belt along the western part of the outcrop area and that the boundary
between these rocks and the dominant tuff portion may be tectonic. In
the Healy quadrangle, a thin interbed of volcaniclastic sandstone in the
tuff yielded fossils of late Sinemurian age (R.W. Imlay, cited in
Csejtey and others, 1992). Csejtey and others (1992) indicate that
because these fossils were from near the top of the tuffaceous section,
that the section may be as old as Late Triassic. Some chert beds in
other parts of the unit have yielded Late Jurassic (Callovian to early
Tithonian) radiolaria and the calcareous rocks yielded early Sinemurian
fossils at several localities (Csejtey and others, 1992) \[symbol 905\]
3850 (unit JTrta, HE002) Also (5010 and 4235, units JTrsv and Trvs,
TL002)

**T[r]{.smallcaps}lb Limestone and basalt sequence** (Late Triassic,
Norian)\-- Interlayered limestone and amygdaloidal basalt flows.
Limestone is medium-gray, massive to thick-bedded and locally altered to
fine- to medium-grained marble. Fossils including *Monotis
subcircularis*, indicate age. Basalt is dark-to greenish-gray, aphanitic
and contains numerous amygdules. Character of the unit suggests
shallow-water deposition and chemistry of the basalts suggests an ocean
island shield volcano (Csejtey and others, 1992). Occurs as thrust
slivers in the Chulitna sequence in the Healy quadrangle and extends a
short distance into the Talkeetna quadrangle (unit T[r]{.smallcaps}lb,
HE002; MM002; TL002) \[symbol 838+15\] 4021

**T[r]{.smallcaps}r Red beds** (Late Triassic?)\-- Red sandstone,
siltstone, argillite and conglomerate similar to unit
JT[r]{.smallcaps}su, distinct from it because of the occurrence of
clasts of gabbro, serpentinite, and fossiliferous Permian(?) limestone
(Csejtey and others, 1992). Found only in thrust slivers in the
southwestern Healy quadrangle. Unconformably overlies volcanogenic and
sedimentary rocks of Triassic to Devonian age (unit T[r]{.smallcaps}Dv)
(HE002; unit JTrrs, MM002) \[symbol 838+16\] 4060

**T[r]{.smallcaps}Dv Volcanic and sedimentary rocks** (early Triassic to
late Devonian)\-- Intercalated greenish-gray to black tuffaceous chert,
volcanic conglomerate and lesser maroon volcanic mudstone, basaltic
breccia, laminated flysch-like graywacke and shale, large lenses of
light-gray thick-bedded limestone, and poorly exposed beds of
ammonite-bearing limestone (Csejtey and others, 1992) mapped only in the
Healy quadrangle. Fossils include Devonian and Carboniferous fossils in
the chert, Permian fossils including brachiopods in the thick-bedded
limestone and Early Triassic ammonites and conodonts from the limestone.
Probably greenschist facies (Csejtey and others, 1992). Considered one
of the stratigraphically lower parts of the Chulitna sequence (unit
TrDv, HE002) \[symbol 838+14\] 5110

**Dsb Serpentinite, basalt, chert and gabbro** (Late Devonian)\--
Sheared serpentinite tectonically intermixed with chert and pillow
basalt which form lenticular and podiform tectonic blocks (Csejtey and
others, 1992). Radiolaria from the chert are Late Devonian (Fammennian).
Probably a dismembered ophiolite assemblage, unit is lowest part of the
Chulitna sequence. Mapped in the Healy and Mount McKinley quadrangles
(unit Dsb, HE002; MM002) \[symbol 678\] 7325

End of Chulitna Sequence

**Oceanic rocks of the Seventymile, Angayucham, Tozitna, and Innoko
assemblages.** Possibly correlative assemblages of mafic, ultramafic,
and associated, typically chert-rich sedimentary rocks (including the
Rampart Group of Brosge and others, 1969, in the Tanana quadrangle) have
been assigned to the Tozitna, Angayucham, Innoko, and Seventymile
assemblages in the northern part of the compilation area. These
assemblages are similar in lithology, age, and allochthonous occurrence.
It is well accepted that these are oceanic rock packages (Patton and
others, 1994a; Dover, 1994). There is less agreement on the exact nature
and original site of deposition, and amount and direction of transport
of these sequences. On this map, three lithologic subdivisions are shown
in similar colors: 1) ultramafic or dominantly mafic/ultramafic rocks,
2) dominantly sedimentary rocks (with or without greenstone), and 3)
mafic, ultramafic, and associated sedimentary rocks, undivided.

Seventymile assemblage

**JPsu Ultramafic rocks** (Jurassic? and/or **Permian**)\--
Serpentinized peridotite, harzburgite, and dunite. Not directly dated
but age inferred from association with mafic and low-grade
metasedimentary rocks of the greenstone and chert unit (JPzsgs). Unit
restricted to small areas of outcrop in the Big Delta, Fairbanks, and
Circle quadrangles and more extensive exposures to the east of the map
area in the Eagle and Tanacross quadrangles (Foster and others, 1994).
Corresponds to unit Pu in the Big Delta quadrangle (Weber and others,
1978), unit Dmu in the Fairbanks quadrangle (Pewe and others, 1996) and
unit Pzp in the Circle quadrangle (Foster and others, 1983). Unit is
structurally infolded with mafic and pelitic schists of unit PzZysa
\[symbol 468\] 5980, 7090 unit Pu, BD002; unit Pzp, CI002; unit Dmu,
FB002

**JPzsgs Greenstone and chert** (Jurassic? to middle? Paleozoic)\--
Massive greenstone, amygdaloidal pillow basalt and metatuff and
associated metachert, quartzite, phyllite, silica-carbonate lenses, and
other low metamorphic grade sedimentary rocks. Glaucophane-bearing rock
associated with greenstone in the northern Eagle quadrangle, east of the
map area, yielded a Permian Ar-Ar age (Foster and others, 1992, p. 9).
Elsewhere the greenstone is intercalated with chert that yields
radiolaria and rare shelly fossils of Mississippian through Triassic
age. Mafic rocks locally contain glaucophane. Includes the Pgc and Pq
units of Weber and others (1978) in the Big Delta quadrangle, and the
Pzg unit of Foster and other (1983) in the Circle quadrangle \[symbol
461\] 5830, 5960 units MzPzgc, Pq BD002; 5640 unit Pzg, CI002

Angayucham assemblage

**Jaum Ultramafic rocks (Jurassic?)**\-- Serpentinized peridotite,
dunite, and harzburgite, having associated layered gabbro and
anorthosite, and locally garnet-amphibolite tectonite, possibly derived
from eclogite at the base. Forms the upper part of the Angayucham
assemblage along the southeast margin of the Yukon-Koyukuk basin and the
northwest flack of the Ruby metamorphic complex. Primary igneous
minerals and textures are preserved, yet most contacts strongly to
cryptically deformed, especially at the structural base of the unit.
K-Ar hornblende ages from hornblende gabbro and hornblende-bearing dikes
range from 172 to 138 Ma and dates from garnet-amphibolite range from
172 to 155 (Patton and others, 1977; Patton and others, 1994a). All are
considered cooling ages related to tectonic emplacement of the
ultramafic and mafic rocks. Considered part of a dismembered ophiolite
derived from the root of a volcanic arc, rather than a mid-ocean ridge
setting (Loney and Himmelberg, 1985; Patton and others, 1994a; see also
Patton and others, 1994b). Includes unit JPu in the Melozitna (Patton
and others, 1978) and Tanana quadrangles (Chapman and others, 1982),
unit Juu in the Nulato quadrangle (W.W. Patton, Jr., written commun.,
1977), and unit Ju of Dover (1994) \[symbol 468\], 5150 (MZ002; NL003;
TN002; RB004; unit Jmu, TN003)

**JMab Basalt and chert** (Jurassic? to Mississippian)\-- Dominantly
basalt, greenstone, gabbro, diabase, and chert. Minor basaltic tuff,
volcanic breccia, and carbonate rocks. Basalt and greenstone include
pillow basalt and metamorphosed spilitic basalt. Unit consists of
discontinuous and large unsheared blocks and lenses of incipiently
recystallized mafic rocks in a low metamorphic grade, blastomylonitic,
metasedimentary matrix. Matrix is bedded chert of Triassic age,
argillite, slate, limestone of Mississippian age, and andesitic and
basaltic tuff. Locally, the metamorphic minerals glaucophane, prehnite,
and pumpellyite are present. Unit is thermally metamorphosed along
contact with middle Cretaceous (110-120 Ma, unit Kg) plutons in the
Melozitna and Tanana quadrangles. Includes unit JPb in the Melozitna
(Patton and others, 1978) and Ruby quadrangles (Chapman and Patton,
1978), unit JMms (Chapman and others, 1982) and JMbc (Dover, 1994) in
the Tanana quadrangle, and the westernmost part of unit
T[r]{.smallcaps}Mb in the Nulato quadrangle (W.W. Patton, written
commun., 1997) \[symbol 464\] 5140 (unit JPb, MZ002; RB004; unit TrPv,
KH003; unit JMbc, TN003)

Tozitna assemblage north of the Kaltag Fault

**JMtru Greenstone, chert, and ultramafic rocks, undivided** (Jurassic?
to Mississippian?)\-- Poorly dated spilitic basalt and diabase largely
altered to greenstone. Locally, includes minor sedimentary rocks,
generally low metamorphic grade cataclastic assemblage of generally dark
gray chert and siliceous argillite. Also includes subordinate
volcaniclastic rocks and minor Mississippian limestone. Mafic,
ultramafic, and associated metasedimentary rocks of the Tozitna terrane
of Silberling and Jones (1984; see fig.2, herein) in the Tanana and
Circle quadrangles are part of this unit. Similar rocks occur on strike
to the northeast in the Bettles quadrangle (Patton and Miller, 1973).
Includes unit T[r]{.smallcaps}Pv in the Tanana (Chapman and others,
1975) quadrangle, unit T[r]{.smallcaps}Mru in the Tanana quadrangle
(Reifenstuhl and others, 1997), and unit MzPzc, the Circle Volcanics, in
the Circle quadrangle (Foster and others, 1983). The origin, original
setting, and tectonic emplacement of these rocks are discussed by
Churkin and others (1982), Coney and Jones (1985), Gemuts and others
(1983), Dover (1994), Foster and others, 1994, and Patton and others,
1994a \[symbol 464\] 5132, RB003; RB004; new TN003 unit assigned

**JT[r]{.smallcaps}tmu Mafic and ultramafic rocks** (Jurassic? to
Triassic)\-- Diabase, gabbro, leucogabbro, and greenstone; ultramafic
rocks include serpentinized peridotite, harzburgite, and werhlite.
Locally, may include minor associated sedimentary rocks. Tentative age
range based on K-Ar age of 210+/-6 Ma reported by Brosge and others
(1969; age recalculated using constants of Steiger and Jager, 1977) on
gabbro in Rampart Group, and stratigraphic and/or intrusive relationship
with rocks as young as Triassic. Includes unit T[r]{.smallcaps}Mrg in
the Tanana B-1 quadrangle (Reifenstuhl and others, 1997), unit
T[r]{.smallcaps}Mrv in the Livengood quadrangle (Weber and others, 1992)
(Foster and others, 1983) \[symbol 468+16\] 5130, unit TrMrv, LG002;
unknown label in TN003

**T[r]{.smallcaps}Mts Sedimentary rocks** (Triassic to Mississippian)\--
Chert, metachert, metatuff, quartzite, phyllite, and other associated
incipiently metamorphosed sedimentary rocks; includes basalt and
amygdaloidal pillow basalt in places. Corresponds to the Rampart Group
of Brosge and others (1969) in the Tanana quadrangle, the
T[r]{.smallcaps}Mra, T[r]{.smallcaps}Mrb, T[r]{.smallcaps}Mrs, and
T[r]{.smallcaps}Mrl units of Reifenstuhl and others (1997) in the Tanana
B-1 quadrangle, and the T[r]{.smallcaps}Mrs unit of Weber and others
(1992) in the Livengood quadrangle and unit PaMc of Foster and others in
the Circle quadrangle \[symbol 461\] 5020 unit TrMrs, LG002; unit JMms,
TN002; unit PaMc, CI002; unit JMr, TN003

Tozitna assemblage south of the Kaltag Fault

**JMtu Mafic, ultramafic, and sedimentary rocks, undivided** (Jurassic
to Mississippian)\-- Basalt, gabbro, diabase, basaltic tuff, and chert.
May include minor ultramafic rocks and other associated low metamorphic
grade metasedimentary rocks in the Nulato, Ophir, and Ruby quadrangles
that resemble the Tozitna assemblage north of the Kaltag fault
interpreted as an offset equivalent. Poorly dated. Corresponds to the
eastern parts of unit T[r]{.smallcaps}Mb of Patton (written commun.,
1997) in the Nulato quadrangle, unit TrMb in the Ophir quadrangle
(Chapman and others, 1985), and parts of units mc and mi in the Ruby
quadrangle (Cass, 1959). A large area in the northwest part of the Ruby
quadrangle is shown as this unit; however, we believe on the basis of
information from R.M. Chapman (oral commun., 1998) that unit JMtu
primarily occurs capping ridges and that rocks of the Ruby metamorphic
complex occur at lower elevations. Further mapping will be necessary to
resolve the geology of this area \[symbol 464\] 5133 unit TrMb, OP002;
NL003; part of units mc, mi, RB002, parts of unit mi, NL002; Puchner
units, unknown, RB004?

**Jtu Ultramafic rocks, undivided** (Jurassic)\-- Cumulate ultramafic
rocks, harzburgite tectonite, and other ultramafic rocks, undivided;
K-Ar ages on hornblende of 151+/-4.5, 172+/-5.2 and 269+/-8 Ma reported
by Patton and others (1984), the Permian age is considered spurious.
Corresponds to unit Ju of Patton and others (1984) and the informal Jcu,
Jht, and Juu units of Patton (written commun., 1997) in the Nulato
quadrangle \[symbol 468\] 3496, 3497, 3498 units Jcu, Jht, Juu, NL003

**JPztm Mafic and ultramafic rocks, undivided** (Jurassic? and/or
Paleozoic?)\-- Gabbro sills and subordinate quartz diorite, quartz
monzonite, and pyroxenite. Undated; age and assignment to the Tozitna
assemblage based on lithologic associations and regional comparisons.
Corresponds to informal Pzmi unit of Puchner (1984) in western Ruby
quadrangle \[symbol 468\] 5113 unit Pzmi of (Puchner), RB005

**T[r]{.smallcaps}Mtqp Quartzite and phyllite** (Triassic? to
Mississippian?)\-- Quartzite, phyllitic quartzite, phyllite, and
subordinate limestone. Occupies a position structurally between the
Tozitna assemblage and the Ruby metamorphic complex south of the Kaltag
fault. Originally assigned to the Slate Creek thrust panel of the
Angayucham terrane (see fig. 2) by Patton and others (1994a) and to the
Ruby metamorphic complex by Puchner (1984), we have provisionally
assigned it to the Tozitna assemblage herein based on lithologic
compatibility, map distribution and its distinctly lower metamorphic
grade than the underlying Ruby metamorphic complex. Poorly dated and of
controversial age; Dillon and others (1986) assigned similar rocks in
the Wiseman quadrangle a Triassic to Mississippian age on the basis of
radiolaria from intercalated chert layers whereas Patton and others
(1994a) prefer a Devonian age, based on palynflora also in the Wiseman
and, additionally, the Christian quadrangles. Corresponds to the
T[r]{.smallcaps}Mq unit of Patton (written commun., 1997) in the Nulato
quadrangle and unit Pzrp of Puchner (1984) in the western Ruby
quadrangle. A similar, but more highly metamorphosed quartzite unit in
the Melozitna quadrangle (unit PzpCq, Patton and others, 1978) is here
shown within unit PzZrpg of the Ruby metamorphic complex; W.W. Patton,
Jr. (personal commun., 1998) suggest these may represent the same unit
\[symbol 461+16\] 5542 unit Pzc, KH003 **(is this unit part of this?;
unit TrMq, NL003; unit PzpCq, MZ002; unit Pzrp {Ruby phyllite}, RB005**

**T[r]{.smallcaps}Mtsu Sedimentary rocks, undivided** (Triassic? to
Mississippian?)\-- Rocks tentatively correlated with the Rampart Group
of the Tanana quadrangle, including chert, slate, siltstone,
meta-graywacke, basalt, greenstone, and minor limestone. Corresponds to
informal Pzrg unit and its\' subdivisions of Puchner (1984) in western
Ruby quadrangle \[symbol 461\] 5131 (no such code) units Pzrgmsv, Pzrgs,
RB005

Innoko assemblage

**Jium Ultramafic and mafic rocks, undivided** (Jurassic to
Mississippian?)\-- Peridotite, dunite, serpentinite, harzburgite
tectonite, and cumulate ultramafic rocks of the Mt Hurst area, and
subordinate gabbro, diorite, and basalt. Age based on dating of
correlative rocks in the Tozitna sequence of the Nulato quadrangle.
Includes ph and pc units of Chapman and others (1985) in the Ophir
quadrangle. In the Iditarod quadrangle, gabbronorite, gabbro and diabase
and associated serpentinized harzburgite, minor dunite and rare
pyroxenite of the Dishna River mafic and ultramafic rocks (Miller and
Bundtzen, 1994) occur as fault-bounded slivers along the Dishna River
fault zone \[symbol 468\] 5191, units ph, pc, OP002; unit Jdr, ID002

**JT[r]{.smallcaps}ta Cherty tuff, crystal and lithic tuffs, and
volcanic breccia** (Early Jurassic? and Triassic)\-- Dark greenish, very
fine-grained cherty tuff grading into greenish-gray radiolarian chert.
Also fine- to coarse-grained crystal and lithic tuffs. Volcanic breccia
and conglomerate composed of poorly sorted clasts of mafic volcanic
rocks and cherty tuff in a crystal and lithic tuff matrix. Age
assignment is from widespread radiolaria and conodonts from the cherty
beds. Mapped only in the Medfra quadrangle (unit JT[r]{.smallcaps}t,
Patton and others, 1980). Unit assigned to the Innoko terrane (see fig.
2, herein) by Patton and others (1980); however unit is unique in the
Rampart Group related terranes (Innoko, Tozitna, and Angayucham) because
of its young age relative to other units and its tuffaceous character.
Unit outcrops in a distinctive band east of the more typical Innoko
terrane rocks. Very similar in age and lithology to unit
JT[r]{.smallcaps}ct of the Chulitna sequence, but there is little reason
to believe that these are the same unit \[symbol 464\] 3851 unit JTrt,
MD002 \[thought largely Triassic in age, Jim Dover would put in Rampart
Group equivalent\]

**T[r]{.smallcaps}Mis Sandstone, grit, and argillite** (Triassic to
Mississippian)\-- Calcareous graywacke, grit, chert-argillite-clast
pebble conglomerate, and subordinate interbedded argillite, tuff, and
volcaniclastic rocks. Poorly dated but may overlie T[r]{.smallcaps}Mica
unit. Corresponds to the T[r]{.smallcaps}Ms unit of Chapman and others
(1985) in the Ophir quadrangle \[symbol 461+13\] 5021 (unit TrMs, OP002)

**T[r]{.smallcaps}Mica Chert, argillite, and volcaniclastic rocks**
(Triassic to Mississippian)\-- Dominantly medium-dark- to dark-gray,
thin-banded, bedded radiolarian-bearing chert having thin interbeds of
slaty argillaceous rocks, including argillite, slate, and phyllite. Also
includes subordinate intermediate to basaltic volcanic and
volcaniclastic rocks including lithic and waterlaid tuff, fossiliferous
shallow-water limestone, grit, and arkosic sandstone lenses. Age range
based on radiolaria of Mississippian age, conodonts, and foraminifera of
Mississippian age collected from unit in the Ruby and Medfra quadrangles
(Chapman and Patton, 1979). Latest Devonian radiolaria were collected in
two localities in the southwestern Ruby quadrangle (Chapman and Patton,
1979) and are the only Devonian fossils known from unequivocal Innoko
assemblage rocks; however Patton and others (1994a) report Devonian
palynflora from the Wiseman and Christian quadrangles in the similar
Angayucham assemblage. A K-Ar age of 302+/-9 Ma on amphibole from tuff
indicates a Pennsylvanian age (Miller and Bundtzen, 1994). This unit
originally described by Chapman and Patton (1979) and redefines part of
the Cretaceous chert and argillite unit of Cass (1959, unit Kc).
Corresponds to the T[r]{.smallcaps}Mc unit of Chapman and others (1985)
in the Ophir quadrangle and Miller and Bundtzen (1994) in the Iditarod
quadrangle. Includes the PaMc unit of Patton and others (1980) in the
Medfra quadrangle. Corresponds to the informal MDc unit of Puchner
(1984) in the western Ruby quadrangle \[symbol 461\] 5025, unit TrMc
5021?, 5111, 5112, 6080, 6390 unit PzpCs or T[r]{.smallcaps}Mc, OP002;
unit TrMc, ID002; units PaMc, MD002; unit MDc, RB003; RB005

**Pig Graywacke** (Permian)\-- Fine- to medium-grained, medium-gray to
dark-greenish-gray, locally calcareous, graywacke and grit to
small-pebble graywacke conglomerate, and greenish-gray to medium-dark
gray mudstone and shale. Originally described by Chapman and Patton
(1978); unit redefines part of the Cretaceous chert and argillite unit
of Cass (1959, unit Kc). Probable Permian microfossils and bryozoan and
echinoderm fragments were collected from the northern of two localities
(Chapman and Patton, 1978) are basis of unit age. Mertie and Harrington
(1924) reported a possible ammonite fragment of indeterminate age in the
southern outcrop area, which Cass (1959) used to infer a Cretaceous age.
Known only from the Ruby quadrangle, mapped as unit Pg of Chapman and
Patton (1978) and Puchner (1984) in southwestern Ruby quadrangle, which
Chapman and Patton (1978) correlated with the Rampart Group \[symbol
461+14\] 5745, 1810, part of unit Kc, RB002; unit Pg, RB003; RB005

**MDl Fine-grained limestone** (Mississippian? to Devonian?)\-- Light-
to medium-dark-gray, fine-grained, slightly recrystallized,
conodont-bearing limestone containing minor calcite veinlets and lenses.
Includes minor chert granules and mafic rock fragments, chiefly
concentrated in thin layers, and rare thin layers containing poorly
preserved stromatoporoids, crinoid fragments, and shelly debris
including an unidentified brachiopod. Found in small outcrop exposures
and lenses within unit TrMica of this map in the Ophir (unit MDl,
Chapman and others, 1985) and Medfra (unit PaMcl, Patton and others,
1980) quadrangles Includes the PaMc and PaMcl units of Patton and others
(1980) in the Medfra quadrangle and MDl unit of Chapman and others in
the Ophir quadrangle. \[symbol 704\] 6320, 6380 unit MDl, OP002; unit
PaMcl, MD002

End of Oceanic rocks group

**Stratigraphic sequences**\
Mystic sequence

**JDm Mystic stratigraphic sequence, undivided** (Jurassic to
Devonian)\-- Mapped only in reconnaissance, but presumed to consist of
some of the rock types listed below under descriptions of the Tatina
River Volcanics, Sheep Creek, and St. John Hill Formations: basalt,
limestone, siltstone, sandstone, and various other minor rock types.
Locally sub-divided into: \[symbol 458\] 5375 unit Pzmu, LH004

**JT[r]{.smallcaps}tv Tatina River Volcanic and equivalent units**
(Early Jurassic, Sinemurian? and Triassic)\-- Where best studied in the
McGrath quadrangle (Bundtzen and others, 1997a), consist of three
members.\
\
Upper member (unit lJs of Bundtzen and others, 1997a) consists chiefly
of green medium-grained, concretion-rich volcaniclastic sandstone,
subordinate medium- to very dark-gray, phosphatic shale, and minor tan
chert-pebble conglomerate. Lower Jurassic ammonite-bearing phosphatic
shale beds in the western Talkeetna quadrangle, which Reed and Nelson
(1980) assigned to their unit KJs are reassigned to this member.\
\
A lower volcanic member (unit T[r]{.smallcaps}ab of Bundtzen and others,
1997a) consists of dark-greenish-gray elongate bodies of pillow basalt.
Includes interbeds and lenses of mudstone, shale, and siltstone.
Locally, gabbro bodies, interpreted as feeders to the pillow basalt
flows are included in the unit. In the western Talkeetna quadrangle,
includes basaltic rocks mapped by Reed and Nelson (1980) as units KJb
and Pzbs. Each of these units has similar reported major element oxide
contents and also show similar copper content between 200 to 500 ppm.
Age control is lacking; assignment based on association with other
members. Laterally gradational with the volcanic member is a
volcaniclastic member (unit T[r]{.smallcaps}s of Bundtzen and others,
1997a), which consists of brown silty shale and light-gray, green, and
black chert associated with coarse volcanic sandstone and conglomerate.
Bundtzen and others (1997a) reported the occurrence of *Monotis
subcircularis*, indicating a Late Triassic (Norian) age (unit KJb,
TL002; units lJs, Trab, Trs, MG002; unit Trb, MG003; unit Pzbs, TL002)
\[symbol 420\] 2890, 3210, 4215, 5450, **Mystic**

**PMl Younger limestone** (Permian to Mississippian)\-- Brown to gray,
layered to nodular limestone, calcareous siltstone, varicolored chert,
and limestone-chert conglomerate. Conglomerate contains rounded clasts
of silty sandstone, chert, and limestone. Conodonts indicate a Late
Mississippian age (Bundtzen and others, 1994). Shown separately only in
western Lime Hills quadrangle \[symbol 458\] 6335 unit PPl, LH00?

**PDsc Sheep Creek Formation and correlative siliciclastic units**
(Permian to Devonian)\-- Clastic-dominated, but heterogeneous, middle
third of the Mystic stratigraphic sequence. Consists of sandstone,
conglomerate, siltstone, and argillite, and lesser chert and limestone.
Age control is provided by conodonts, fusilinids, brachiopods, corals,
and plants. Depositional environments are dominantly fluvial, but
carbonate-platform and deep marine environments are also represented by
the subordinate rock types in this grouping of units. Includes Sheep
Creek Formation of eastern and western McGrath and western Lime Hills
quadrangles, units Pacg and uPzac of eastern McGrath quadrangle
(Bundtzen, unpublished data, 1997; 1998; Bundtzen and others, 1997a),
the conglomerate of Mt. Dall (unit Pag) in the Talkeetna quadrangle
(Reed and Nelson, 1980), and unit Ps of Medfra quadrangle (Patton and
others, 1980). The Conglomerate of Mt. Dall, which has yielded a Permian
plant assemblage of Siberian affinity (Mamay and Reed, 1984), contains
clasts of Devonian limestone of the Mystic stratigraphic sequence, and
chert, chert-pebble conglomerate, and graded sandstone, presumably
derived from the Dillinger stratigraphic succession. Conglomerate of
unit Ps in Medfra quadrangle (Patton and others, 1980) contains clasts
of limestone of the subjacent Nixon Fork sequence \[symbol 458+15\] 6010
unit Pad, TL002; unit PDs, MG002; units PDs, uPzs, uPzac, MG003; unit
Ps, MD002

**Dsc Shale and chert** (Devonian)\-- Occurs in limited area in eastern
Lime Hills quadrangle. Important because unit hosts Gargaryah
bedded-barite deposit. Age Middle to Late Devonian (Givetian to
Frasnian) \[symbol 458+14\] 6911 unit Dsc, LH004

**Dml Older limestone** (Devonian)\-- Chiefly algal-laminated limestone
and dolostone of shallow-marine origin. In eastern McGrath quadrangle,
includes members Dls (consisting of limestone, mudstone, siltstone, and
lithic sandstone) and uDl of the St. John Hill Formation, and members
lDl and lDd of the Sheep Creek Formation (Bundtzen and others, 1997a).
In the western McGrath and western Lime Hills quadrangles, includes unit
uDl. Age, constrained by conodonts, corals, and brachiopods, is chiefly
Late Devonian (Frasnian) \[symbol 458+708\] 6931, 6932 units uDl, lDd,
lDl, MG002; unit uDl, MG003; units lDl, uDl, LH004

End of Mystic sequence

Mystic and Dillinger stratigraphic sequences, undivided

**JCmd Mystic and Dillinger stratigraphic sequences, undivided**
(Jurassic to Cambrian)\-- Includes rocks in the Healy, Mount McKinley,
and Talkeetna quadrangles, which appear to correlate with the Dillinger
and Mystic sequences of the eastern McGrath quadrangle, but which have
only been studied in reconnaissance. Jurassic to Cambrian quoted
encompasses the entire age range of the Mystic and Dillinger sequences
where they are better studied; fossils within the area mapped as
undivided Mystic and Dillinger range from Permian to Silurian. In the
Talkeetna quadrangle (Reed and Nelson, 1980), unit Pzus (the original
Mystic terrane of Jones and Siberling (1979) consists of a structurally
complex assemblage of deep marine facies (siliciclastic turbidites,
cherty pelagite, pillow basalt, and wildflysch), slope and shelf facies
(chert, shale, and reefoid limestone), and nonmarine facies
(conglomerate and sandstone). Fossil ages range from Early Devonian to
Permian; strata below the Devonian limestone in this belt belong to the
Dillinger sequence. In the Healy quadrangle (Csejtey and others, 1992)
and Mount McKinley quadrangle (Bela Csejtey, Jr., written commun.,
1993), units DOs and DOls, respectively, consist of a complexly folded
assemblage of (1) fine-grained, calcareous, siliceous, and siliciclastic
strata, (2) calcareous siliciclastic turbidites containing a Late
Silurian to possibly Early Devonian conodont fauna (corresponding to the
Terra Cotta Mountains Sandstone of Bundtzen and others, 1997a), and (3)
calcareous turbidites and debris flows that have yielded Early Silurian
conodonts (Dumoulin and others, in press). Separately mapped carbonate
bodies within the outcrop belt of undivided Dillinger and Mystic strata
are here assigned to unit DSmdl: \[symbol 458+13\] 5370 unit DOs, HE002;
MM002; units DOs?, MM002; unit Pzus, TL002

**DSmdl Unnamed limestone** (Devonian and Silurian)\-- Limestone bodies
within the outcrop area of the undivided Dillinger and Mystic
stratigraphic sequences. In the Talkeetna quadrangle, includes Silurian
and Devonian limestones that were mapped as separate units by Reed and
Nelson (1980). Silurian unit (unit Sl, Reed and Nelson, 1980) consists
of light-gray to light-brown massive-weathering meta-limestone and local
thin-bedded to laminated limestone; age based on graptolites,
*dasclydacean* algae, and corals. Fossil content suggests, at face
value, both shallow and deep marine environments. Devonian limestone
(unit Dl, Reed and Nelson, 1980) contains locally abundant corals and
stromatoporoids, and brachiopods (of Siberian affinity, Blodgett and
Brease, 1997), indicative of shallow marine deposition. Corals,
brachiopods, and conodonts indicate Early to Late Devonian (Emsian to
Frasnian) age. In the Mount McKinley and Healy quadrangles, includes
limestone bodies within units DOs and DOls (Bela Csejtey, Jr., written
commun., 1993; Csejtey and others, 1992), respectively. Recent work by
Dumoulin and others (in press) using conodonts for age control showed
that the previously mapped limestone unit \[(ls)DOs\] in the Healy
quadrangle includes both Silurian deep-water limestone and Late Devonian
shallow-water limestone \[symbol 836\] 6615 units Dls, MG002; units Sl,
Dl, TL002; unit (ls)DOs, HE002; MM002

End of Dillinger and Mystic sequences, undivided

Sedimentary rocks

**T[r]{.smallcaps}Ps Sedimentary rocks, undivided** (Triassic to
Permian)\-- Dominantly dark gray, typically phyllitic, siliceous to
carbonaceous argillite and shale, with subordinate but characteristic
clast-supported chert-rich conglomerate, greenish-gray chert, tuffaceous
volcaniclastic rocks, yellowish- to reddish-brown highly calcareous
argillite or limestone, and minor intrusive rocks; locally may include
older (Mississippian? or Devonian?) or younger (Cretaceous) rocks
(Dover, unpublished data, 1997). Mapped in Tanana quadrangle. In
Livengood quadrangle, equivalent rocks have been subdivided into two
units, Trsc and Ps (unit Trsc, TN003; unit Trc and Ps, LG002) \[symbol
841\] 5012, 4110

**T[r]{.smallcaps}Pas Flysch-like sedimentary rocks** (Late Triassic to
Pennsylvanian)\-- Intensely folded sequence of dark-gray to black,
massive to thin-bedded marine flysch-like rocks including conglomerate,
sandstone, siltstone, and argillite, a few thin interbeds of limestone,
and thin interbeds of chert in the upper part (Csejtey and others,
1992). Age based on Triassic radiolaria and conodonts from cherts and
calcareous units and on a reported collection of Pennsylvanian
brachiopods (see Csejtey and others, 1992, p. 28). Thought at least
several hundred meters thick. Overlain by and locally interbedded with
late Triassic pillow basalt, herein assigned to the Nikolai Greenstone
(unit T[r]{.smallcaps}n) of this map. However, Csejtey and others (1992)
did not assign either of these units to known packages or assemblages
because of the discontinuous and fault-bounded nature of their
occurrence (HE002; MM002) \[symbol 902\] 5040

Igneous rocks

**MzPzi Intrusive and volcanic rocks, undivided** (Mesozoic or
Paleozoic)\-- Granodiorite of Rainbow Mountain in the Mount Hayes
quadrangle (unit grrm, Nokleberg and others, 1992a), diorite in the
Circle and Bid Delta quadrangles (unit MzPzd, Foster and others, 1983;
unit Pzd, Weber and others, 1978), and gabbro and quartz diorite in the
Talkeetna, Tyonek, and McGrath quadrangles (unit MzPzg, Reed and Nelson,
1980; unit MzPzm, Magoon and others, 1976; unit MzPzi, Bundtzen and
others, 1997a, T.K. Bundtzen, written commun., 1997). Also dark-gray to
greenish-gray dikes ranging from basalt to granodiorite in the Talkeetna
quadrangle (unit MzPzi, Reed and Nelson, 1980) and volcanic rocks of
unknown age in the Nulato and the Lime Hills quadrangles (unit vr, W.W.
Patton, Jr., written commun., 1997; unit MzPzi, Reed and Gamble, 1988)

\[symbol 347\] 5160, 5120, 5170, 5175, 5180, 5440 (unit grrm, MH002;
unit MzPzd, CI002; unit Pzd, BD002; unit MzPzg, TL002; unit MzPzm,
TY002; unit MzPzi, MG002; MG003; unit, MzPzi, TL002; unit vr, NL002;
unit MzPzi, LH003)

**MzZum Ultramafic and mafic rocks, undivided** (Mesozoic?, Paleozoic?,
and (or) Late Proterozoic?)\-- Serpentinite, peridotite, dunite, gabbro,
diorite, metabasite, and minor talc schist and roddingite are widespread
throughout map area. These exhibit a broad range of intrusive and (or)
metamorphic textures and fabrics. Age control is generally poor and
inferred ages range from Mesozoic to late Proterozoic. 40Ar/39Ar dating
of hornblende from gabbro in the Tanana quadrangle yielded an apparent
540 Ma age and similar dates in the Livengood quadrangle yielded ages
ranging from 465 to 536+/-2.6 Ma (Reifenstuhl and others, 1998). In the
Talkeetna quadrangle, includes serpentinite and minor talc schist that
Reed and Nelson (unit MzPzu, 1980) interpreted was derived from
peridotite. Includes unit MzPzum in the Tyonek quadrangle (Magoon and
others, 1976), units Pzd and Pzu in the Big Delta quadrangle (Weber and
others, 1978), units PzZm and CZum in the Livengood quadrangle (Weber
and others, 1992), unit PzpCm in the Nulato quadrangle (Patton, written
commun., 1997), and unit Pzum of Reifenstuhl and others (in press) in
the Tanana A-1 (1:63,360-scale) quadrangle. In the Healy quadrangle,
includes two metagabbro intrusions north of the Denali fault system of
inferred Devonian age (unit Dmg, Csejtey and others, 1992) \[symbol
640\] 5190, 5290, 5440, 5690, 7330, 8250, 8450 (unit MzPzd, TL002; unit
Dmg, HE002; unit MzPzum, TY002; unit Pzu, Pzd, BD002; units CZum, PzZm,
LG002; unit Pzug, CI002; unit PzpCm, NL003; serpentinite part of unit
Jsc, TN003) \[*TL002 = Chulitna?*\]

Metamorphic rocks

**JPzk Kakhonak Complex** (Jurassic, Triassic and older?)\-- Within map
area, consists of poorly described metasedimentary, and metavolcanic
rocks tentatively correlated with the Kakhonak Complex. Best described
by Detterman and Reed (1980) in the Iliamna quadrangle to the south of
the map area, the unit is a heterogeneous assemblage of largely
greenschist facies metamorphic rocks. However, the rocks are most
commonly exposed as roof pendants within the Alaska-Aleutian Range
batholith (Reed and Lanphere, 1969; 1972; 1973) and therefore locally
display contact metamorphic effects. Lithologies listed by Detterman and
Reed include argillite and slaty argillite, marble, quartz- mica schist,
and quartzite and there is mention but no description of metavolcanic
and metaplutonic rocks. In our map area, we have included a variety of
metamorphic rocks exposed in associated with the Alaska-Aleutian Range
batholith in the Tyonek and Lime Hills quadrangle within this unit. The
rocks include units Mzs, Mzv, and Mzu of Reed and Elliott (1970) in the
Tyonek and Lime Hills quadrangles, JPu of Magoon and others (1976) and
MzPzs of Gamble and Reed (1996) \[symbol 488\] 5220, unit JPu, TY002;
unit MzPzs, LH002, tentative; 4905, unit Mzs, TY003; 4910, unit Mzv,
TY003; 4920, unit Mzu, TY003

PALEOZOIC\
Assemblages and sequences\
Skolai Group

This assemblage of rocks comprises a lower(?) unit of gabbro and gneiss
(Pennsylvanian?), a middle volcanic and volcaniclastic sequence (Permian
and Pennsylvanian) and a carbonate unit (Permian). The upper units are
known under various names such as the Skolai arc, Skolai Group, Mankomen
Group, Strelna metamorphic assemblage, and the Metamorphic Complex of
Gulkana River and are regarded by many workers, as the basement of the
Wrangellia terrane of Jones and others (1977). Although not originally
defined as part of Wrangellia, they are now commonly included in it.
Rock units and assemblages similar to these are widespread in southern
Alaska, ranging from Puale Bay on the Alaska Peninsula (Wilson and
others, in press) to southeast Alaska.

**Pe Eagle Creek Formation** (Early Permian)\-- Alternating marine
argillite and limestone disconformably overlying the Slana Spur
Formation (Nokleberg and others, 1992a). Limestone is fine- to
medium-grained, thin- to medium-bedded and was deposited in shallow
water at or near wave base. Abundant fossils include a heterogeneous
assemblage of coral, bryozoan, brachiopod, echinoid, crinoid, fusulinid,
and algal(?) fragments. Argillite member is chiefly thin-bedded and
dark-gray and has thin lenses and laminae of gray siltstone and minor
bioclastic limestone, calcareous siltstone and pyritic sandstone. Thin
units of radiolarian chert, shale, and limestone occur within the
Formation. May be as much as 1,000-m-thick. Disconformably overlain by
the Nikolai Greenstone (unit T[r]{.smallcaps}n) and conformably overlies
the Slana Spur Formation (equivalent to Station Creek Formation, in
part). Stratigraphically and lithologically correlative with the Hasen
Creek Formation of the McCarthy quadrangle (MacKevett, 1978).
Metamorphosed to lower greenschist facies \[symbol 506\] 5630

**PPasc Station Creek and Slana Spur Formations, and equivalent rocks**
(Early Permian and Pennsylvanian)\-- Divided into two informal units:
Lower volcanic member consists chiefly of submarine andesite and basalt
flows, locally pillowed and brecciated; upper volcaniclastic member
generally grades upward from coarse volcanic breccia, to abundant
volcanic graywacke, and finally to volcanilutite. No fossils are known
in the type area. Age assignment is relative to overlying Hasen Creek
Formation (Early Permian, MacKevett, 1978) and stratigraphic and
lithologic correlation with the Slana Spur Formation (Nokleberg and
others, 1992a). As here mapped, includes unit Pzt of Nokleberg and
others (1992a) consisting of aquagene tuff, argillite, limestone, chert,
andesitic tuff, and greenstone which have yielded fragments of late
Paleozoic bryozoans. In the Talkeetna Mountains quadrangle, Early
through Late Permian conodonts were collected from unit Pzv (Csejtey and
others, 1978) (unit Pzt, MH002; Early Permian and Pennsylvanian(?), unit
Pzv, TK002; unit PPsc, Station Creek Fm., MC002) Slana Spur Formation
(unit PaPsl, MH002; unit Ps, NB002; unit PPs, GU002)

**Pat Tetelna Volcanics** (Pennsylvanian)\-- Chiefly greenish volcanic
flows, mud and debris avalanches, and lapilli-pumice tuff interbedded
with fine- to coarse-grained volcaniclastic rocks (Nokleberg and others,
1992a). Flows are mainly andesitic and are correlative with volcanic
flows member of the Station Creek Formation. Metamorphosed to lower
greenschist facies. As here mapped, unit also includes greenstone of the
Skolai Group in the Valdez quadrangle (Winkler and others, 1980) and
Early Permian(?) and Pennsylvanian andesitic volcanic rocks in the Healy
quadrangle (Csejtey and others, 1992) \[symbol 506+14\] 5620, 5621,
6120, 6220 (units PaPs, PaPsl, PaPsu, MH002; units Pzv, PPt, NB002; unit
Pt, GU002) Greenstone, Skolai Group (unit Pzs, VA002; unit PPav, HE002)

**Pmi Shallow stocks, dikes, and sills** (Early Permian?)\-- Sparse to
locally abundant andesite, and subordinate dacite and rhyolite stocks,
dikes, and sills (Nokleberg and others, 1992a). Intrudes Slana Formation
and Tetelna Volcanics but not the Eagle Creek Formation (Nokleberg and
others, 1992a). Age inferred from intrusive relations. Metamorphosed to
lower greenschist facies. Locally intense hydrothermal alteration and
associated sulfide mineralization (unit Pi, MH002) \[symbol 177\] 5860

**PPagi Ahtell pluton** (Permian and Pennsylvanian)\-- Fine- to
coarse-grained granite, quartz monzonite, granodiorite, tonalite, and
minor quartz diorite. Crops out in the northeastern Gulkana quadrangle.
Intrudes Tetelna Volcanics. U-Pb age of 311 Ma (Nokleberg and others, in
press). Locally metamorphosed to lower greenschist facies. Consists of
units PPaf, PPap, and PPag of the Gulkana quadrangle (Nokleberg and
others, in press) and unit PPag of Mount Hayes quadrangle (Nokleberg and
others, 1992a) (unit Pm, MC002; units PPf, PPp, PPg, GU002; unit Pag,
MH002) \[symbol 177+13\] 5870, 6110

**PPad Diorite complex** (Permian to Pennsylvanian)\-- Diorite,
granodiorite, and altered diabase and gabbronorite. Crops out in the
northeastern Gulkana quadrangle. Intrudes Tetelna Volcanics. U-Pb ages
of 295 to 319 Ma (Nokleberg and others, in press). Locally metamorphosed
to greenschist facies. Units PPaa, and PPad of the Gulkana quadrangle
(Nokleberg and others, in press) (units PPd, PPa, GU002 \[symbol
177+14\] 5880

**Pagb Gabbro and orthogneiss** (Pennsylvanian?)\-- Thick complex of
layered gabbro or locally, interlayered gneiss and gabbro conformably
overlain by the Skolai Group in the Valdez quadrangle (Winkler and
others, 1980). Gabbroic parts of the unit are interpreted as part of the
oceanic crust that underlies the Skolai arc; the significance and origin
of the gneiss is uncertain, it has affinities to members of the
charnokite series (unit Pzg, VA002; unit Pago, MC002; unit Pzg, NB002)
\[symbol 177+15\] 5460

**PPast Strelna metamorphic complex** (Early Permian to Middle
Pennsylvanian)\-- Variably metamorphosed but largely lower greenschist
facies metasedimentary and metavolcanic rocks of the Skolai Group.
Includes quartzofeldspathic and quartz-mica schist, locally having
compositional layering reflecting original bedding, greenstone derived
from mafic to intermediate volcanic rocks, and locally abundant marble
interbeds and tectonic lenses and metachert and orthogneiss. Metamorphic
grade generally increases to amphibolite facies near contacts with the
Uranatina River metaplutonic complex (unit JPaur, herein). Tightly
folded and pervasively faulted in most localities. Generally undated,
the Strelna metamorphic complex is on trend with similar strata
containing age-diagnostic conodonts in marble (Plafker and others,
1985). Included here is the Strelna metamorphic assemblage of the Valdez
quadrangle (G.R. Winkler, written commun., 1998) and the metamorphic
complex of Gulkana River units ds, mmp, am, mha, mcb of the Gulkana
quadrangle (Nokleberg and others, in press), the nonplutonic older part
of the Haley Creek terrane of Winkler and others (1980), units Jgs and
Jam of Csejtey and others (1978) in the Talkeetna Mountains quadrangle,
and unit Jma in the Anchorage quadrangle (Winkler, 1992). Also includes
migmatitic border rocks (unit Jpmu) of the Jurassic plutons and
undifferentiated metamorphic and plutonic rocks (unit Jgdm) in the
Talkeetna Mountains quadrangle (Csejtey and others, 1978) (unit PPsm,
MC002) Strelna (units Ja, Psm, VA002; units ds, mmp, mha, qmfs, mcb,
GU002; units Jpmu \[3600\], Jgdm \[3621\], Jgs \[5641\], Jam \[5550\],
jmrb and jmb \[5955\], TK002; unit Jma \[5550\], AN002) \[symbol
506+348\] 5550, 5625, 5641, 5680, 5920, 5203, 5204, 5209

**PPaskm Marble** (Early Permian? and Pennsylvanian?)\-- White, medium-
to coarse-grained marble occurring as massive lenticular interbeds, as
much as 30-m-thick in the Strelna metamorphic complex in the Talkeetna
Mountains quadrangle (units Jmrb, Jmb, and Pls Csejtey and others, 1978)
and marble within the Skolai Group in the Valdez quadrangle (unit Pzm,
Winkler and others, 1980; unit ma, G.R. Winkler, written commun., 1998).
In the Talkeetna Mountains quadrangle, the protolith may have been
limestone within the Talkeetna Formation (unit Jtk) or within the Late
Paleozoic volcanogenic rocks (unit PPasc) (units Khcm, Pzm, VA002; units
Jmrb, Jmb, Pls, TK002) \[In Valdez, now labeled ma\] \[symbol 506+13\]
5955 (unit M, VA002) 2720

End of Skolai Group

Dillinger and Nixon Fork sequences

The term Dillinger has been widely used in Alaska for a Cambrian to
Devonian succession of mostly deep-marine strata, which outcrop in the
southwestern part of the present map area. These rocks have been
assigned to the Dillinger terrane (Silberling and others, 1994; see fig.
2, herein), Dillinger subterrane of the Farewell terrane (Bundtzen and
others, 1997), and Dillinger sequence of the present compilation. On the
present map, the Dillinger sequence is broken out into constituent
formations in parts of its outcrop belt, but is left undivided in the
Sleetmute, Lime Hills, and Talkeetna quadrangles. The term Nixon Fork
has been widely used in Alaska for a late Proterozoic to Devonian
succession of mostly shallow-marine carbonate rocks, which also outcrop
in the southwestern part of the present map area. These rocks have been
assigned to the Nixon Fork terrane (Silberling and others, 1994; see
fig. 2, herein), Nixon Fork subterrane of the Farewell terrane (Bundtzen
and others, 1997), and Nixon Fork sequence of the present compilation.
On the present map, the Nixon Fork sequence is broken out into
constituent formations in most of its outcrop belt, but is left
undivided where mapped in reconnaissance in the Sleetmute and Lime Hills
quadrangles and in a limited part of the Medfra quadrangle. Decker and
others (1994) showed that the Nixon Fork and Dillinger sequences are
laterally equivalent shallow- and deep-water facies of what they termed
the White Mountain sequence.

Dillinger sequence

**DCd Dillinger sequence, undivided** (Devonian to Cambrian)\-- Consists
of the rock types listed below under descriptions of Post River and
Lyman Hills Formations, Terra Cotta Mountains Sandstone, and Barren
Ridge Limestone \-- all interpreted as slope or basinal deposits. Age
control is from conodonts and graptolites. Includes units Pzd in
Talkeetna quadrangle (Reed and Nelson, 1980), Pzu in eastern Lime Hills
quadrangle (Gamble and Reed, 1996), Pzdu in western Lime Hills
quadrangle (T.K. Bundtzen, unpublished data, 1998), East Fork Hills
Formation (Dutro and Patton, 1982) DOsl (age extended by conodonts to
include Cambrian, Dumoulin and others, in press) in Medfra quadrangle
(Patton and others, 1980, now East Fork Hills Formation of Dutro and
Patton, 1982). In the northwestern Mount McKinley quadrangle, includes
unit Pzc, which consists of chert and slate that has yielded Ordovician
graptolites, quartz-rich turbiditic sandstones and minor interbedded
limestone yielding Early Silurian (Llandoverian) conodonts (Dumoulin and
others, in press), and quartzite that has yielded Silurian to Devonian
corals (W. Oliver, written commun., 1997). Where subdivided, includes
the following units: \[symbol 10\] 5310 unit Pzd, TL002; unit Pzc,
MM002; unit Pzu, LH002; LH003; unit Pzdu, LH004, part of unit Pzl,
SM002; unit DOsl, MD002

**Dsbr Barren Ridge Limestone and correlative units** (Late Devonian to
Late Silurian)\-- Thin- to thick-bedded, buff to orange-weathered,
light- to medium-gray, phyllitic calcarenite, thin-bedded orange to buff
siltstone, and light-gray silty limestone. Age based on conodonts.
Deposited in a basinal and (or) slope setting. Includes Barren Ridge
Limestone in eastern McGrath and western Lime Hills quadrangles
Bundtzen, unpublished data, 1997; 1998). Is the upper third of the
Dillinger stratigraphic succession \[symbol 10+708\] 6952 unit DSl,
MG002; MG003; LH004

**Stc Terra Cotta Mountains Sandstone and correlative units** (Late and
middle Silurian)\-- Chiefly calcareous sandstone and interbedded
graptolitic shale. Mappable members include silty limestone,
volcaniclastic sandstone, micaceous calc-sandstone, chert, and
argillaceous graptolitic limestone. Sedimentary structures such as
graded bedding, flute casts, and cross-lamination indicate deposition by
turbidity currents in a deep-marine setting. Age based on graptolites.
Includes various subdivisions of the Terra Cotta Mountains Sandstone of
Bundtzen and others (1997a) (units mSs, mSl, mSvs, uSsl) in the eastern
McGrath quadrangle (Bundtzen and others, 1997a), unit mSs in western
McGrath (Bundtzen, unpublished data, 1997), and unit mSs in western Lime
Hills quadrangles (Bundtzen, unpublished data, 1998). Is the middle
third of the Dillinger stratigraphic succession \[symbol 7\] 6660, units
uSsl, mSl, mSvs, mSs, MG002; unit mSs, MG003; unit mSm, LH004

**SCpl Post River Sandstone, Lyman Hills Formation, and correlative
units** (middle Silurian (Wenlockian) to Late Cambrian)\-- Post River
Formation (Churkin and Carter, 1996) consists of graptolitic shale,
siltstone, and chert; Lyman Hills Formation of Bundtzen and others
(1997a) consists of silty limestone and shale, commonly cross-laminated,
locally containing Bouma \'cde\' intervals. Age constrained by uppermost
Cambrian conodonts and Ordovician and Silurian graptolites. Deposited in
a basinal and(or) slope setting, in part by turbidity currents. Includes
the Lyman Hills and Post River Formations in their type areas in the
eastern McGrath quadrangle (Bundtzen and others, 1997a; Bundtzen,
unpublished data, 1997), unit OCls, which intertongues with the Nixon
Fork sequence in the western McGrath quadrangle (Bundtzen, unpublished
data, 1997), unit Oc in the Talkeetna quadrangle (Reed and Nelson,
1980), and part of unit mcb in the Ruby quadrangle (Cass, 1959). This
combined unit forms the lower third of the Dillinger stratigraphic
sequence \[symbol 10+15\] 7580 units lSl, SOsh, OCls, MG002; part of
unit mcb, RB002; units SOsh, OCls, Clm MG003; unit Pzc, MD002; unit Oc,
TL002; units OCls, SOsh, LH004

End of Dillinger sequence

Nixon Fork sequence

**DZn Shallow-marine carbonate units of Holitna basin area, undivided**
(Devonian to Late Proterozoic)\-- shallow-marine limestone and dolostone
facies having reported algal reefs. Middle Devonian to Middle Cambrian
age range indicated by trilobites, conodonts, corals, stromatoporoids,
and brachiopods; an unfossiliferous dolostone unit below Middle Cambrian
strata has been assigned to Late Proterozoic (St. John and Babcock,
1997). Map distribution compiled from Miller and others (1989), Bundtzen
(unpublished data, 1998), and Decker and others (1994). Locally includes
the following units: \[symbol 900+708\] 8340, 8345 part of unit Pzh,
MG003; part of unit Pzl, SM002

**DSwc Whirlwind Creek Formation and unnamed correlative units** (Late
Devonian, Frasnian through middle Silurian, Wenlockian)\--
Shallow-marine limestone and dolostone comprises the upper third of the
Nixon Fork stratigraphic sequence in its type area in the Medfra
quadrangle. Age range is based on conodonts, stromatoporoids, corals,
and ostracodes. Depositional setting interpreted as shallow marine.
Includes Whirlwind Creek Formation in Medfra quadrangle (Patton and
others, 1980; Dutro and Patton, 1982), unit DSl in the Mt. McKinley
quadrangle (Bela Csejtey, Jr., written commun., 1993), units lDl, lDd,
mDl, SLa, and SDlw in the western McGrath quadrangle (Bundtzen,
unpublished data, 1997), and unit SDlw(h) in the western Lime Hills
quadrangle (Bundtzen, unpublished data, 1998) \[symbol 900+14\] 6960
unit DSl, MD002; MM002; units lDl, lDd, mDl, Sla, SDlw, MG003; unit
SDlw(h), LH004

**Spf Paradise Fork Formation and unnamed correlative rocks** (middle
Silurian, late Llandoverian to Wenlockian)\-- Dark, platy limestone and
limy shale. Is the middle third of the Nixon Fork sequence in its type
area in the Medfra quadrangle. Age based on conodonts and graptolites.
Depositional setting interpreted as deeper water, off-platform. Includes
the type Paradise Fork Formation in Medfra quadrangle (Patton and
others, 1980; Dutro and Patton, 1982) and unit Ssh in the western
McGrath quadrangle (Bundtzen, unpublished data, 1997) \[symbol 900\]
6620, 6660 unit Sls MD002; unit Ssh, MG003

**Ont Novi Mountain and Telsitna Formations, and unnamed correlative
rocks** (Ordovician and late Cambrian?)\-- Novi Mountain Formation
consists of variably argillaceous limestone, distinctively orange
weathering in places, and locally oolitic. The overlying Telsitna
Formation is mainly peloidal lime micrite and lesser dolostone. Age is
based on conodonts, corals, and brachiopods. Depositional setting
interpreted as shelf, locally very shallow. Unnamed units in the western
McGrath quadrangle include breccia, argillite, laminated limestone, and
mudstone, some of which may have been deposited in deeper-water
settings. Includes Novi Mountain Formation (unit Od of Patton and
others, 1980; Dutro and Patton, 1982) and Telsitna Formation (unit Osl
of Patton and others, 1980; Dutro and Patton, 1982) in their type areas
in the Medfra quadrangle (Dutro and Patton, 1982). Also includes unit Ol
in the Ruby quadrangle (Cass, 1959), and units Ol, lOlb, mOl, uOl, uOll,
and Om in western McGrath quadrangle (Gilbert, 1981; Bundtzen,
unpublished data, 1997). Also includes somewhat problematic dolostones
that rest on crystalline basement in the northernmost Medfra quadrangle,
which Dutro and Patton (1982) assigned to the Telsitna Formation. These
strata have yielded the gastropod *steinkerns* that allow the
possibility of an age as old as Late Cambrian \[symbol 900+16\] 7520
unit Od, Osl(Novi Mountain.), MD002; unit Ol, RB; units mOl, uOl, uOll,
Ol, lOlb, OCm MG003

**CZds Unnamed dolostone, sandstone, siltstone** (Early Cambrian to
Proterozoic)\-- Alternating intervals of 1) yellow, brown, and maroon
siltstone and cross-bedded quartzose sandstone, and 2) dolostone,
consisting of packstone and grainstone having coated grains and
fenestral fabric. The siliciclastic rocks probably accumulated in a
marginal-marine environment; the dolostone in a shallow marine shelf or
platform. Devoid of fossils, unit is assigned a pre-Middle Cambrian age
because similar strata underlie Middle Cambrian trilobite-bearing rocks
in the Sleetmute quadrangle (Miller and others, 1989). Includes units
Xmso, Xcd, and Xcl in western McGrath quadrangle (T.K. Bundtzen,
unpublished data, 1997) \[symbol 900+238\] 8350 unit Xmso, XCd, XCl,
MG003

End of Nixon Fork sequence

Sedimentary rocks

**Pzlc Limestone and chert** (Paleozoic)\-- Light- to dark-gray lime
mudstone, locally argillaceous in eastern exposures and interbedded with
chert in western exposures. Occurs only between strands of the Tintina
fault in the Circle quadrangle in the so-called \"Preacher Block\" of
Foster and others (1983). No fossils are known from unit and Foster and
others (1983) suggest rocks in the eastern and western exposures may be
of significantly different ages. Unit is at least 350 m thick \[symbol
573+708\] 5330 unit Pzl, CI002

**Ps Argillite, siltstone, sandstone, and minor conglomerate**
(Permian)\-- Thinly and rhythmically interbedded dark-gray argillite and
platy, laminated, gray siltstone. Very fine- to fine-grained, gray,
chert-rich, turbiditic sandstone. Quartz- and chert-bearing granule- to
pebble conglomerate, locally calcareous and fossiliferous. Foraminifera,
conodonts, and brachiopods indicate a Permian age (Weber and others,
1992). Mapped in the Livengood quadrangle. In the Tanana quadrangle,
equivalent rocks are part of unit T[r]{.smallcaps}Ps (unit Ps, LG002;
unit TrPs, TN003) \[symbol 841+15\] 5740

**PDms Sedimentary rocks** (Permian? to Devonian?)\-- Indeterminate or
poorly identified units in Livengood quadrangle. Black and greenish-gray
siliceous slate, thinly interbedded gray chert, shaly chert, and minor
breccia, siliceous, locally sandy siltstone displaying turbiditic
sedimentary structures, red and greenish-gray, or dark-gray, locally
calcareous shale, phyllite, minor quartz- sandstone, argillite,
greenstone, lime mudstone to packstone, and limestone debris flows.
Conodonts from a limestone clast in one debris flow indicate a Late
Devonian (Famennian) age (Weber and others, 1992). Includes units PDms
and Pzs in the Livengood quadrangle (Weber and others, 1992) \[symbol
841+14\] 5600, 5615

**Mgq Globe quartzite** (Mississippian)\-- Light gray, massive or thinly
laminated quartzite and medium- to dark-gray slate, phyllite, and
laminated claystone. Unfossiliferous; age inferred on the basis of
intrusion by Triassic rocks and by lithologic and stratigraphic
similarity with the Keno Hill quartzite of Yukon Territory, Canada
(Dover, 1994). Associated with gabbroic dikes and sills. Occurs in the
White Mountains and Schwatka stratigraphic belts in Livengood and Tanana
quadrangles and has limited exposure in the Circle quadrangle (F.R.
Weber, unpublished mapping, 1998) \[symbol 516+238\] 6530 unit Mg,
LG002; Vitreous quartzite unit of MzPzaq, CI002; unit Mg, TN003

**Dps Phyllite, slate, siliceous siltstone, and argillite**
(Devonian)\-- Light- and medium-gray to silvery gray phyllite, slate,
siliceous siltstone, and argillite. Includes some thin limestone and
calcareous siltstone. Unfossiliferous; Devonian age assigned on the
basis of two equivocal observations: 1) unit Dps appears to overlie
limestone (unit DSl of the present compilation) which locally has
yielded Late Devonian (Frasnian) corals, but 2), unit Dps is also
possibly gradational with unit DSl (Chapman and others, 1975). Mapped
only in the Kantishna River quadrangle \[symbol 573\] 6902 KH002 Dps,
Pzcs, DOs

**Dcb Cascaden Ridge, Beaver Bend, and correlative rocks**
(Devonian?)\-- Various Devonian siliciclastic units in the Livengood and
Circle quadrangles. Cascaden Ridge unit of Weber and others (1992),
exposed in Livengood quadrangle, is chiefly rhythmically interbedded
gray and olive-gray shale, gray siltstone, and graywacke. Less abundant
components are gray limestone and polymictic granule- and pebble
conglomerate having a graywacke matrix. Conglomerate clasts include
mafic/ultramafic rocks, chert, dolomite, and shale (Weber and others,
1992). Limestone contains Middle Devonian conodonts, brachiopods, and
corals. Beaver Bend unit of Weber and others (1992), is conglomerate,
graywacke, siltstone, and slate in the Livengood quadrangle.
Conglomerate is polymictic, clast-supported granule- to pebble-sized and
has clasts that include chert, quartz, quartzite, mafic and felsic
volcanic rocks, argillite, slate, siltstone, and sandstone. Graywacke is
fine- to medium-grained; framework grains are mostly chert and quartz,
and subordinate slate. Unit has yielded unidentifiable plant fragments;
however, it is assigned a probable Devonian age. In the western Circle
quadrangle, unfossiliferous chert-pebble conglomerate mapped as unit
part of MzPzat by Foster and others (1983) is assigned to Beaver Bend
unit (F.R. Weber, unpublished mapping, 1998). In north-central Circle
quadrangle, north of the Tintina fault, two units mapped by Foster and
others (1983) are included here: unit Pzcg, chert-pebble conglomerate;
and unit Pzcc, chert, chert-pebble conglomerate, and minor limestone.
Limestone of unit Pzcc yielded Late Devonian (Famennian) conodonts.
Combined unit correlates with the Nation River Formation of the Charley
River quadrangle (Brabb and Churkin, 1969) \[symbol 573\] 6940, 6941
(unit Dc, LG002; unit Pzcc, Pzcg, and part of unit MzPzat, CI002

**Dq Quail unit** (Devonian)\-- Gray and green phyllite interlaminated
with calcareous siltstone, quartzose sandstone, graywacke, and granule-
to boulder conglomerate constitute the Quail unit of Weber and others
(1992). Clasts in conglomerate include chert, dolostone, serpentinite,
intermediate and mafic igneous rocks, quartzite, argillite, phyllite,
slate, volcanic rocks, sandstone, and white quartz. At base are
localized carbonate buildups of coral-bearing lime-mudstone and
wackestone of Late Devonian (Frasnian) age (Weber and others, 1992).
Slightly higher metamorphic grade than age and lithologically similar
Cascaden Ridge unit of Weber and others (1992), here mapped as part of
unit Dcb. Correlates with the Nation River Formation of the Charley
River quadrangle (Brabb and Churkin, 1969) \[symbol 570\] 6920 unit Dq,
LG002

**Dtr Troublesome unit and possibly correlative rocks** (Devonian?)\--
Rhythmically interbedded dark-gray to black cherty argillite to chert,
and thin beds of black to gray, siliceous slate as mapped in the
Livengood quadrangle. Associated with extensive mafic intrusive and
extrusive rocks. Unidentified radiolaria are only reported fossils
(Weber and others, 1992). Depositionally overlain by Frasnian carbonate
buildups at base of Quail unit, hence Middle Devonian or older. Also
includes unit Pzc in the Circle quadrangle, which consists of chert
interlayered with argillite, and rare marble and quartzite, intruded by
diorite and gabbro (Foster and others, 1983). Radiolaria from unit Pzc
are not age-diagnostic but reported as \"possibly of Mississippian age
(Foster and others, 1983)\"; this constraint is, however, less
compelling than the pre-Frasnian age for the Troublesome unit in its
type area. May correlate with the McCann Hill Chert of the Charley River
quadrangle (Brabb and Churkin, 1969) \[symbol 573\] 6910 unit Dt, LG002;
unit Pzc, CI002

**Ds Schwatka limestone unit** (Middle to Early Devonian)\-- Slightly
recrystallized, dark-gray, sparsely fossiliferous, medium-bedded to
massive, lime mudstone or wackestone. Conodonts and two-holed crinoid
ossicles constrain age to Emsian to Eifelian (Weber and others, 1992).
Interfingers with volcanic rocks of unit Dsv. Mapped only in
northeastern Livengood and northwestern Circle quadrangles. Depositional
environment interpreted as shallow marine \[symbol 900\] 6945 (Unit Dls,
LG002, CINEW \-- was 6966 on CI002)

**Dsv Volcanic part of Schwatka unit** (Middle to Early Devonian)\--
Massive basalt flows, agglomerate, tuff, fine-grained volcaniclastic
rocks, minor thin lenses of laminated platy impure limestone, and local
lenticular bodies of calcite-cemented conglomerate (Weber and others,
1992) interbedded with limestone of unit Ds. Metamorphosed to
greenschist facies. Mapped in Livengood and Circle quadrangles \[symbol
900+348\] 7010 unit Dsv, LG002; CI003

**DSlc Lost Creek unit** (Devonian and Silurian?)\-- Light-gray,
massively bedded, lime mudstone and wackestone. Limestone occurs as
debris flows that pinch out laterally and contain rip-up clasts of
shale, chert, and other sedimentary rocks. Basal part of unit contains
channels of graywacke and chert pebble and cobble conglomerate incised
into the underlying Livengood Dome Chert (mapped here within unit Oc).
Channels and debris flows together indicate a deep-water depositional
setting. Brachiopods, corals, and trilobites indicate a Late to middle
Silurian age (Wenlockian to Ludlovian). A separate band of micritic
limestone, flanked by chert and assigned a possibly Silurian or Devonian
age, was included in this unit by Weber and others (1992) \[symbol 602\]
6955

**DSl Limestone** (Late Devonian to middle Silurian)\-- Various
shallow-marine, carbonate-dominated rocks of Silurian to Devonian age in
the Circle, Tanana, Kantishna River, and Livengood quadrangles, except
the Tolovana and Schwatka units, which are shown by their own symbols.
In the Circle quadrangle, includes unit Dl of Foster and others (1983),
medium-gray, generally massive, locally recrystallized limestone which
is found in scattered outcrop belts north of the Tintina fault. It has
yielded Early Devonian conodonts from several localities (Foster and
others, 1983). In the Tanana quadrangle, includes the following units of
Dover (unpublished mapping, 1997): 1) unit Dld, which consists of light-
to medium-gray or tan sandy, platy limestone and massive-bedded
silicified limestone and dolostone, of Late Devonian (Famennian) age; 2)
\"unit Ml\", gray, bioclastic limestone of Famennian in age; and 3) the
limestone of Raven Ridge, which consists of gray micritic limestone and
brecciated limestone, of Late Devonian(?) age. In the Kantishna River
quadrangle, includes unit Dls of Chapman and others (1975), which is
chiefly medium- to dark-gray limestone, dolomitic in part, and
medium-gray shaly to phyllitic siltstone. This unit has yielded Late
Devonian (Frasnian) corals from one locality (Chapman and others, 1975).
In the Livengood quadrangle, consists of light- to medium-gray lime
mudstone or wackestone. Locally corals and stromatoporoids are common
and conodonts at several localities suggest a Frasnian (Late Devonian)
age (A.G. Harris, written commun., 1984-1988; cited in Weber and others,
1992). \"These bodies, as thick as 30 m have a lateral extent of several
hundred meters in the basal Quail unit, were deposited as local biogenic
buildups on the Troublesome unit (Weber and others, 1992)\" \[symbol
900\] 6944, 6930 unit Dls, KH002, unit Dl, KH004; units Dlr, Dld, Ml,
TN003; unit Dl, CI002; unit Dql, LG002

**DSt Tolovana Limestone** (Middle Devonian to Early Silurian)\-- Lower
part of alternating green and maroon lime mudstone, succeeded by
yellowish-brown weathering, silty to shaly lime mudstone and wackestone,
and a main, upper part of light-weathering peloid- and ooid-rich lime
packstone and grainstone and rare dolostone in the White Mountains of
east-central Livengood quadrangle. Conodonts, brachiopods, and corals
indicate an Early Silurian age. In the same strike belt in southeastern
Livengood quadrangle, a somewhat younger (Middle Devonian) unit of lime
mudstone and wackestone has also been assigned to the Tolovana
Limestone; this subunit continues into the Fairbanks and Kantishna River
quadrangles. Rocks formerly assigned to the Tolovana Limestone in
northwesternmost Circle quadrangle are herein assigned to the Schwatka
unit (unit Ds); rocks formerly assigned to the Tolovana Limestone in
north-central and northeastern Circle quadrangle are herein to unit DSl.
Depositional environment interpreted as shallow marine \[symbol 900\]
6965 (unit DSt, FB002; LG002; unit Dst, KH003, KH004)

**SZa Amy Creek unit** (Silurian to Late Proterozoic)\-- In Livengood
quadrangle were described by Weber and others (1992), consists chiefly
of medium-grained gray dolostone, and light-gray, yellow-gray, or buff
dolomitic mudstone, packstone, and wackestone. Coarser-grained rocks
show abundant peloids and crossbedding; laminations present in mudstone;
solution breccia and algal coatings present. Other interbedded rock
types include chert, black argillite, lime mudstone, basaltic
greenstone, tuff, tuffaceous siltstone, shale, and minor volcaniclastic
graywacke (Weber and others, 1992). In the Tanana quadrangle, consists
of white, massive, locally laminated cherty dolostone having gray
limestone at top and bottom of section (Dover, unpublished mapping,
1997). In the Circle quadrangle, consists of yellow-gray dolomite and
gray to dark-gray and black argillite, shale, and siltstone,
interlayered with light- and dark-gray chert, gray marble, and gray,
fine-grained quartzite (Foster and others, 1983). Age poorly
constrained; age range given here is from Weber and others (1992). Must
be older than the fossiliferous Middle Devonian strata that overlie it,
and at least in part Cambrian or younger because it has yielded sponge
spicules and unidentifiable radiolaria \[symbol 788\] 6680 unit SZa,
LG002; unit PzpCb, CI002; unit Za, TN003; 6681 unit DSd, CI002

**Oc Chert** (Ordovician)\-- Dark gray and black chert, siliceous slate,
argillite, and less abundant greenstone, impure limestone, and
dolostone. Age assigned on basis of graptolites. Includes the Livengood
Dome Chert in the Livengood, Circle, and Tanana quadrangles, unit Pzlc
in Tanana quadrangle (Dover, unpublished mapping, 1997), the Nilkoka
Group in Fairbanks quadrangle (Pewe and others, 1966), and unit DOc in
Mount McKinley and Kantishna River quadrangles (Bela Csejtey, Jr.,
written commun., 1993; Chapman and others, 1975) \[symbol 10+15\] 7710
unit Old, LG002; unit nc, FB002; unit Oc, TN002; KH002; KH003; unit DOc,
KH004; unit Old, CI002; unit Olc, TN003; unit DOc, MM002

**Ocl Limestone** (Paleozoic?)\-- Distinctive marker bed of lime
mudstone within chert unit, locally characterized by coated ooids.
Thickness varies from 10 to several ten\'s of meters, probably in part
due structural thickening and repetition. Only mapped locally.
Corresponds to unit Pzl, in part, of Chapman and others (1982) in the
Tanana quadrangle \[symbol 616\] 7711 (unit Pzl (part), TN002; unit
Pzll, TN003)

Igneous rocks

**Pzvs Volcanic and sedimentary rocks** (late or middle Paleozoic)\--
Dark-greenish-gray mafic volcanic rocks and interbeds of black phyllite,
chert-pebble conglomerate, light-green tuff, and graywacke (Reed and
Nelson, 1980). Volcanic rocks include pillow basalt, breccia
agglomerate, tuff, and massive basalt flows. Distinguished from unit
Trpb (this map, unit Pzbs, Reed and Nelson, 1980) by presence of massive
basalt flows (unit Pzv, TL002; unit Pzvs, KH003) \[symbol 403+13\] 5410

**Ofc Fossil Creek Volcanics** (Ordovician)\-- Two members, one largely
volcanic, one largely sedimentary. Volcanic member consists of alkali
basalt, agglomerate, and volcaniclastic conglomerate. Agglomerate and
conglomerate contain well-rounded clasts of basalt, granite, quartzite,
limestone, chert, and phyllite. Sedimentary member consists of shale,
chert, and limestone which are intruded by gabbro. Late Ordovician
brachiopods, trilobites, gastropods, and conodonts have been recovered
from sedimentary rocks in the volcanic member; Early Ordovician
conodonts and trilobites have been recovered from the sedimentary member
(Weber and others, 1992). Mapped in the White Mountains stratigraphic
belt of Livengood, Circle, and Tanana quadrangles (Dover, 1994).
Laterally equivalent to Livengood Dome Chert \[symbol 10+348\] 7610
(unit Ofv, Ofs, LG002; unit SOs, CI002, CINEW; unit Ofc, TN003)

Metamorphic rocks

**PMpc Phyllite and chert** (Permian to Mississippian)\-- Two map units
of Bundtzen and others (1997a) in eastern McGrath quadrangle are
included in this unit: (1) unit uPzs, composed of dark gray-green to
distinctly maroon, pyrite-rich volcanogenic phyllite, and (2) unit uPzc,
white-weathered, gray-green, banded phyllitic ribbon chert. The latter
has yielded Permian through Pennsylvanian radiolaria and Permian through
Mississippian conodonts (Bundtzen and others, 1997a). Assigned by
Bundtzen and others (1997a) to Yukon-Tanana terrane \[symbol 461\] 5545

**Dy Yanert Fork sequence and correlative rocks** (Devonian and
older)\-- Metasedimentary and metavolcanic rocks having variable degrees
of penetrative fabric and metamorphic grade, found between the Hines
Creek strand and main Denali faults, in the Healy, Mount McKinley, and
Mount Hayes quadrangles. Includes argillite, slate, phyllite,
phyllonite, semischist, impure quartzite, schistose stretched-pebble
conglomerate, banded metachert, felsic metatuff, and metabasalt, all
intruded by Mesozoic(?) diabase and gabbro. Sedimentary textures and
pillow structure preserved in places. Grade dominantly greenschist
facies but ranges to amphibolite facies eastward into the Mount Hayes
quadrangle. Conodonts from a marble interbed indicate a Late Devonian
age (Csejtey and others, 1992). Protolith interpreted to represent a
volcanic-bearing continentally derived turbiditic marine sequence
deposits on the continental slope. Considered part of the Yukon-Tanana
terrane by Csejtey and others (1992) and depositionally overlain by the
T[r]{.smallcaps}cs unit; tentatively correlated with rocks of similar
age and lithology (units hgs and hgv) in the Hayes Glacier subterrane of
Nokleberg and others (1992a) in the Mount Hayes quadrangle, which they
also consider part of the Yukon-Tanana terrane. Includes unit Dy in the
Healy quadrangle (Csejtey and others, 1992) and is correlated with units
hgs and hgv of the Hayes Glacier sub-terrane in the Mount Hayes
quadrangle (Nokleberg and others, 1992a). Subdivided in the Mount Hayes
quadrangle as: \[symbol 509\] 7242, unit Dy HE002; units hgs, hgv, MH002

**Dys Fine-grained schistose sedimentary rocks** (Devonian and older)\--
Fine-grained schistose sedimentary rocks of unit hgs of the Hayes
Glacier sub-terrane in the Mount Hayes quadrangle (Nokleberg and others,
1992a) \[symbol 509+14\] 7402 unit hgs, MH002

**Dyv Fine-grained schistose volcanic rocks** (Devonian and older)\--
Chiefly fine-grained metavolcanic and metasedimentary phyllonites and
blastomylonites of unit hgv of the Hayes Glacier sub-terrane in the
Mount Hayes quadrangle (Nokleberg and others, 1992a) \[symbol 509+15\]
7240 unit hgv, MH002

**Pzsc Spruce Creek sequence and correlative rocks** (Paleozoic)\--
Mainly mafic to felsic metavolcanic rocks and minor greenstone sills,
mappable as separate metavolcanic units in most places. Consists of two
mappable units, a mafic metavolcanic and a felsic metavolcanic unit.
Mafic unit consists predominantly of dark, massive to schistose
metabasalt, metamorphosed andesite, and amphibolite, containing
intercalated quartz- to mafic schist, pelitic schist, phyllite,
metasiltstone, metatuff, and minor chert and marble. Distinctive felsic
unit consists mostly of blastoporphyritic metarhyolite and felsic
schist. Agglomeratic and pillow structures, and relict phenocrysts of
quartz, orthoclase, and plagioclase are preserved locally. Underwent
amphibolite facies metamorphism and later greenschist facies
retrogression. Metarhyolite from the northeast Mount McKinley quadrangle
yields U-Pb zircon dates of 368 and 371 Ma (T.K. Bundtzen, unpublished
data, 1998) and metarhyolite in the vicinity of Fairbanks yields a U-Pb
zircon age of 369 Ma (Aleinikoff and Nokleberg, 1989). U-Pb zircon ages
of 364, 372, and 375 Ma on metavolcanic layers in unit jcv in the Mount
Hayes quadrangle are interpreted to date extrusion of the now
metamorphosed volcanic rocks (Nokleberg and others, 1992a). In the Healy
quadrangle, conodonts of Late Devonian age have been collected (Csejtey
and others, 1992). Unit consists of the Spruce Creek sequence of
Bundtzen (1981) in the northeast Mount McKinley quadrangle, the Muskox
sequence of Newberry and others (1996) in the Fairbanks Mining District,
and units Dmf, Dmb, and Dms in the Healy quadrangle (Csejtey and others,
1992), unit jcv in the Mount Hayes quadrangle (Nokleberg and others,
1992a), and tentatively, unit DSu in the eastern Mount McKinley
quadrangle (Bela Csejtey, Jr., written commun., 1993). May be
correlative with the Yanert Fork sequence of Csejtey and others (1992)
\[symbol 699+13\] 5666, 7243, 7290, 7291, 7300, 7320, units Pzsc, DSu,
DSu?, MM002; units Dmb, Dmf, Dms, HE002; Muskox, FB004; unit jcv, MH002

**Pzlsl Schist, phyllite, limestone, and greenstone** (Early
Paleozoic)\-- Light- to medium-green chloritic schist, light- to
medium-gray with silvery sheen phyllite, light- to medium-gray and
greenish-gray, sandy in part, largely recrystallized limestone, and
light- to medium-green greenstone. Schist and phyllite are partly
calcareous, intensely folded and interbedded with thin limestone beds.
Greenstone is basaltic, less common than other rock types.
Unfossiliferous; probably older than the adjacent Frasnian limestone
(unit DSl). Mapped only in the western Kantishna River quadrangle
(Chapman and others, 1975) \[symbol 788\] Was 5665 KH002, now 6956,
DSls?

PALEOZOIC AND PRECAMBRIAN\
Sequences and Complexes

Yukon-Tanana, Alaska Range, and Ruby metamorphic complexes

Metamorphic rocks of the Yukon-Tanana Upland, Alaska Range, and Ruby
Geanticline (for areas, see figure 2, sheet 3) areas have complex
histories of polyphase deformation and crystallization. Differences in
details of metamorphic, thermal, uplift, and plutonic histories between
the Yukon-Tanana and Ruby areas are discussed in regional studies
(Dusel-Bacon, 1994; Mortensen, 1992; Foster and others, 1994; Dover,
1994; Roeske and others, 1995) prevent confident correlation of the
metamorphic sequences between them. On the other hand, gross
similarities in the composition, lithic content, and inferred protoliths
of these two complexes, and local similarities in at least some aspects
of their crystallization-deformation histories, are consistent with the
possible development of both complexes in a continental arc setting
along the Late Proterozoic to Middle Paleozoic North American
continental margin (Nokleberg and others, 1992a, p. 7; Dover, 1994;
Roeske and others, 1995). This compilation attempts to accommodate
contrasting interpretations by assigning the same or similar map colors
to similar crystalline packages in all areas north of the Denali fault,
while preserving differences previously recognized in local studies by
use of patterns that in part reflect original unit assignments.

Yukon-Tanana and northern Alaska Range metamorphic complex

**Pzydm Dolostone and marble** (Paleozoic)\-- Represents two discrete
units. In the western Circle quadrangle, an isolated mass consists of
massive gray to cream-colored dolostone and gray to greenish-gray marble
interlayered with calcareous greenish-gray and gray quartzite, phyllite,
and calc-silicate. Unit is in fault contact with unit PzZyqs. In the
southeastern Circle, white or cream-colored marble interbeds(?) as much
as 20-m-thick occur in unit PzZysa (Foster and others, 1983) \[symbol
900+13\] 8430 \[se\] 8615 \[w\], ls in PzpCs and unit PzpCd, CI002

**Pze Eclogite-bearing schist** (Paleozoic)\-- Garnet and omphacite
bearing biotite-muscovite schist, micaceous marble, black quartzite, and
amphibolite. Protolith predominantly quartz- and pelitic to calcareous
pelitic sediments, impure limestone, and associated mafic volcanic and
volcaniclastic rocks. Mapped as a distinct allochthon by previous
workers cited below However, the high-pressure eclogite facies mineral
assemblage is restricted to thin interlayers within a metamorphic
sequence that has at least some lithologic similarities with the
structurally underlying quartz- and pelitic schist unit (PzZyqs). P/T
conditions of 11 Kb and 600 to 700°C cited by Newberry and others (1996)
for the eclogite facies assemblage. A Mississippian to Devonian
protolith age inferred from Ar-Ar, K-Ar, and Pb-Pb studies cited in
Newberry and others (1996); a questionable K-Ar Ordovician protolith age
of 478+/-35 Ma on low-K amphibole and K-Ar mica ages ranging from
166.+=/-2.2 to 103.5+/-3.4 Ma attributed to Mesozoic metamorphism were
reported by Forbes (1982). Includes units Pce and Pcu of the Chatanika
assemblage of Robinson and others (1990), unit PDe of Newberry and
others (1996), unit Pzc in the Livengood quadrangle (Weber and others,
1992), and unit PzpCms in the Circle quadrangle (Foster and others,
1983) \[symbol 311\] 5475, 5510 (unit Pze, LG002; PzpCms, CI002; Pzs,
BD002)

**MDyao Augen orthogneiss** (Mississippian and(or) Devonian?)\--
Peraluminous granitic gneiss containing augen of potassium feldspar
generally interpreted to represent a blastoporphyritic texture. U-Pb
zircon data indicate a 341+/-3 Ma crystallization age for augen gneiss
in the Big Delta quadrangle (Aleinikoff and others, 1986); similar augen
gneiss in the Tanacross quadrangle east of map area yielded U-Pb ages of
353+/-4 and 356+/-2 Ma (Dusel-Bacon and Aleinikoff, 1996). Comprised of
unit PzpCa in the Big Delta quadrangle (Weber and others, 1978), and
unit Da in the Circle quadrangle (Foster and others, 1983), and
tentatively includes units lga, lgr, mg, and jcg assigned by Nokleberg
and others (1992a) to the Lake George, Macomb, and Jarvis Creek Glacier
subterranes of the Yukon-Tanana terrane in the Mount Hayes quadrangle.
Rb-Sr biotite, K-feldspar, plagioclase, and whole-rock isochron ages of
about 110 Ma on some of these rocks are interpreted by Wilson and others
(1985) and Nokleberg and others (1992a) as the age of metamorphism
\[symbol 184+16\] 6521, 7250, (units lga, lgr, mg, jcg, MH002; PzpCa,
BD002; Da, CI002)

**MDt Totatlanika Schist** (Early Mississippian to Middle Devonian)\--
Low-grade, multiply-deformed, locally mylonitic assemblage of gritty
semischist containing clear to bluish gray quartz \"eyes\", chloritic
quartzo-feldspathic schist and augen gneiss, phyllitic schist and
semischist, phyllite, metavolcanic rocks, quartzite, marble, and
greenstone. Porphyritic volcanic and sedimentary textures preserved in
places; metavolcanic compositions range from mafic to felsic. Age poorly
defined, from one marble interbed Middle Devonian to Early Mississippian
conodonts, and less precisely dated crinoids, corals, and gastropods
were collected (Wahrhaftig, 1968). Meta-andesite from the northeastern
Big Delta quadrangle yields a U-Pb zircon age of 375 Ma that is
interpreted as an extrusive age of protolith (Dusel-Bacon and others,
1993, p. C-14). Comprised of the Totatlanika Schist of the Fairbanks
(Pewe and others, 1966) and Healy quadrangles (Csejtey and others,
1992), various units of the Totatlanika Schist in the Chena River area
(Smith and others, 1994), and the Pzsg unit of Weber and others (1978)
in the Big Delta quadrangle \[symbol 700\] 6510, 6511 (unit MDt, HE002,
MM002, FB002, unit Pzsg, BD002)

**MDtm Mylonitic Totatlanika Schist** (middle Paleozoic?)\--
Blastomylonitic quartzofeldspathic schist, gneiss, and augen gneiss.
Probably derived from the Totatlanika Schist (MDt). Mapped only in the
Big Delta quadrangle where shown as unit Pzc by Weber and others (1978)
\[symbol 700+238\] 5605 (unit Pzc, BD002)

**Pzk Keevy Peak Formation** (Early Mississippian? to Devonian?)\--
Siliceous and carbonaceous assemblage of phyllite, meta-argillite,
quartzite, metachert(?), and lesser amounts of interlayered calcareous
phyllite, marble, and mafic and felsic metavolcanic rocks. Contains
minor stretched pebble conglomerate in the Healy and Mount McKinley
quadrangles. Locally, calcareous phyllite and semischist at the base of
the unit it is mapped separately and shown as unit Pzkcp. Multiply
deformed; metamorphic grade ranges from lower to upper greenschist
facies. In the Big Delta quadrangle, a 346+/-1 Ma U-Pb zircon age from a
felsic metatuff interlayer indicates an early Mississippian extrusion
age and therefore a depositional age for at least part of the sequence;
Pb-isotope data for syngenetic galena in carbonaceous phyllite-hosted
stratiform zinc-lead deposit also indicates a Mississippian or Devonian
age for mineralization (Dusel-Bacon and others, 1998). Late and Middle
Devonian fossils have been reported in the Mount McKinley quadrangle
(Gilbert and Redman, 1977). Unit appears to occupy regional
stratigraphic position between the Totatlanika Schist and unit PzZyqs of
this map. As mapped, includes the Keevy Peak as originally defined by
Wahrhaftig (1968) in the Healy and Mount McKinley quadrangles; new age
data support extension of the unit to the Big Delta, Circle, and
Fairbanks quadrangles, and correlation with the Nasina assemblage in
Yukon Territory proposed by Weber and others (1978). Includes unit Pzq
in the Big Delta (Weber and others, 1978) and quadrangles (Foster and
others, 1983), unit Pzk in the Healy (Csejtey and others, 1992) and
Mount McKinley (Bela Csejtey, written commun., 1993) quadrangles, and
the upper part of the Birch Hill Sequence (unit Dbs, Newberry and
others, 1996) in the Fairbanks Mining District of the southeastern
Livengood and northeastern Fairbanks quadrangles \[symbol 699\] 5660,
5661 (units Pzk, HE002, MM002; unit Pzq, BD002, unit Pzq, CI002)

**Pzkcp Calcareous and phyllitic rocks** (Devonian or older)\--
Calc-phyllite, marble, and phyllite; lower to upper greenschist facies.
Age unknown. Distributed discontinuously along the basal contact of the
Keevy Peak Formation, and interpreted here as a calcareous, basal part
of the Keevy Peak. Corresponds to the lower part of the Birch Hill
Sequence (Dbcs unit) of Newberry and others (1996) in the southeastern
Livengood and northeastern Fairbanks quadrangles, and unit Pzm in the
Big Delta (Weber and others, 1978) and in the Circle quadrangles (Foster
and others, 1983) \[symbol 699+16\] 5662 (unit Pzm, BD002; CI002)

**PzZym Mafic schist** (Paleozoic and(or) Late? Proterozoic)\-- Green,
quartz-chlorite-carbonate schist, commonly having abundant plagioclase
porphyroblasts. Associated with amphibolitic schist and minor marble,
quartzite, and pelitic schist. Thought to represent metamorphosed mafic
pyroclastic rocks interbedded with schists of unit PzZyqs. Outside of
the map extent shown, these rocks also occur as interbeds in unit PzZyqs
in the Circle quadrangle. Includes unit PzpCm of Foster and others
(1983) and unit Pzcl of Wiltse and others (1995) \[symbol 132+14\] 8660,
unit PzpCm, CI002

**PzZyqs Quartz- and pelitic schist of the Yukon-Tanana Upland** (middle
to early Paleozoic and(or) Late? Proterozoic)\-- Dominantly
polymetamorphic quartzite, schistose quartzite, and quartz-mica schist,
containing subordinate gritty quartzite, chlorite schist, calc-silicate
schist, marble, magnetite-biotite schist, amphibolite, and greenstone.
Ranges from amphibolite to greenschist facies. Protolith age at least as
old as the augen gneiss unit (MDyao) that intrudes it; U-Pb zircon age
of 365 Ma reported from an interlayer interpreted as meta-tuff in the
Big Delta quadrangle (Aleinikoff and others, 1986). K-Ar dating in much
of the Yukon-Tanana Upland has shown that Cretaceous pluton yield ages
distinctly younger than metamorphic ages, that in general there is no
indication of thermal resetting by these plutons, and that therefore
many of the K-Ar ages, typically between 105 and 120 Ma indicate the
timing of metamorphism (Wilson and others, 1985). To the south in the
Mount Hayes quadrangle, Nokleberg and others (1992a) interpreted K-Ar
white mica ages between 106 and 118 Ma on their unit jcs as metamorphic
crystallization rather than cooling ages. Unit PzZyqs corresponds to the
Fairbanks Schist of the Fairbanks Mining District and surrounding areas
of the southeastern Livengood and northeastern Fairbanks quadrangles of
Robinson and others (1990, unit PzPfs) and Newberry and others (1996,
units Zf, Zfa, Zfm, Zfc, Zfg, and Zfw), units Zf and Zfc in the
Livengood quadrangle (Weber and others, 1992), units Pzs, PzpCs, and
PzpCsq (Weber and others, 1978) in the Big Delta quadrangle, unit PzpCq
in the Circle quadrangle (Foster and others, 1983), and pCcq, pCu, pCcm,
and pCm units of the quartz- \"basement\" of Smith and others (1994) in
the Chena River area. Also includes some rocks distinguished by Robinson
and others (1990) in the Fairbanks Mining district as the Chena River
Sequence based on inferred differences in grade, but reassigned to the
Fairbanks Schist by Newberry and others (1996) because their study shows
the Chena River rocks formed under similar T/P conditions and contain
chemically identical amphiboles as the Fairbanks Schist. Devonian
metavolcanic rocks of the Cleary sequence, originally included in the
Fairbanks Schist of Robinson and others (1990), were reassigned by
Newberry and others (1996) to their distinctly younger Muskox Sequence,
which is herein assigned to unit Pzsc \[symbol 132\] 9320, 9321, 9323,
9324, 9326, 9327

**PzZaqs Pelitic and quartzose schist of the Alaska Range**\--
Dominantly pelitic and quartz-rich schist in the Healy and Mount
McKinley quadrangles; includes subordinate calc-schist and feldspathic
schist. Generally underwent greenschist to amphibolite facies
metamorphism, with or without greenschist facies retrogression.
Corresponds to unit PzpCp in the Healy (Csejtey and others, 1992) and
Mount McKinley quadrangles (Bela Csejtey, Jr., written commun., 1993),
the PzpCq unit in the southeast Medfra quadrangle (Patton and others,
1980) and unit Pzsv in the Talkeetna quadrangle (Reed and Nelson, 1980).
Also, for this compilation, tentatively includes the jcs unit of the
Jarvis Creek Glacier subterrane of the Yukon-Tanana terrane in the Mount
Hayes quadrangle (Nokleberg and others, 1992a) \[symbol 132+996\] 8633,
8641, 9322, unit jcs, MH002 {part 9320, part 7400}; unit Pzsv, TL002;
unit PzpCp, HE002, MM002; unit PzpCq, MD002

**PzZysa Schist and amphibolite** (middle to early Paleozoic and(or)
Late? Proterozoic)\-- Medium- to high-grade pelitic schist containing
subordinate quartzite, quartz- schist, calc-silicate rocks and
calc-schist, marble, amphibolite, graphitic schist, and augen gneiss
interbeds. Contains less quartzite and quartz- schist, and more marble
interbeds, and is of generally higher grade than the PzZyqs unit. May
grade in lithology, polymetamorphic history, and metamorphic grade with
the Fairbanks Schist in the Fairbanks Mining District (Newberry and
others, 1996) of the southeastern Livengood and northeastern Fairbanks
quadrangles. The contact with our unit PzZyqs is interpreted as a thrust
by Foster and others (1983) in the Circle quadrangle. The augen gneiss
in the Chena River area was interpreted by Smith and others (1994) to
have a felsic volcanic protolith, and yields K-Ar ages of 76.7+/-1.5 Ma
on biotite, and 82.3+/-3.5 Ma on muscovite (DuBois and others, 1986)
which are considered reset by nearby Latest Cretaceous or Earliest
Tertiary plutonism (Wilson and others, 1984). Foster and others (1992)
inferred the augen gneiss is of Mississippian age by correlation with
augen gneiss of plutonic origin in the adjoining Big Delta quadrangle.
One gneiss body in this area has yielded a concordant Cretaceous (110
Ma) U-Pb zircon age (Dusel-Bacon and others, 1998), however, we do not
have the data at hand to determine the impact this date has on the unit
as a whole. Corresponds to the PzpCs unit (including the sillimanite
gneiss subunit) of Foster and others (1983) in the Circle quadrangle,
and rocks included in the Chena River Sequence of Robinson and others
(1990) and includes the lgs, and ms units of the Lake George and Macomb
subterranes of the Yukon-Tanana terrane in the Mount Hayes quadrangle
(Nokleberg and others, 1992a) \[symbol 136\] 8630, 8632, unit PzpCs,
PzpCs(gneiss), CI002; units lgs, ms, MH002

**PzZyg Gneiss** (Early Paleozoic to Proterozoic)\-- Gray,
medium-grained, mylonitic, quartzofeldspathic biotite-sillimanite
gneiss; associated with unit PzZygs, gneiss, schist, and quartzite.
Forms core of a gneiss dome in the central Big Delta quadrangle
(Dusel-Bacon and Foster, 1983). Age uncertain. Corresponds with Pzg unit
of Weber and others (1978) in the Big Delta quadrangle \[symbol 337\]
5670

**PzZygs Gneiss, schist, and quartzite** (Early Paleozoic to
Proterozoic)\-- Quartzofeldspathic orthogneiss, pelitic schist and
paragneiss, quartzite, and marble. Corresponds to PzpCg unit of Weber
and others (1978) in the Big Delta quadrangle, the quartzite subunit of
unit PzpCs of Foster and others (1983) in the Circle quadrangle, and
includes the pCwo, pCwp, and pCwm units of Smith and others (1994) in
their West Point complex of the Chena River area. Granitic orthogneiss
mapped as part of this unit by Smith and others (1994) yielded and
inferred preCambrian age on the basis of multi-grain U-Pb zircon dating.
However, resampling and redating by Dusel-Bacon and others (1998) using
single grain ion microprobe analysis of zircon from this orthogneiss
yielded a mid-Cretaceous (110 Ma) concordant U-Pb zircon age,
interpreted as an igneous crystallization age synchronous with
high-grade metamorphism, extensional deformation, and exhumation in a
gneiss dome. It is not clear how this new date may impact the inferred
age of the other parts of this unit \[symbol 136+13\] 8802 (new
NSAclass)

End of Yukon-Tanana and northern Alaska Range metamorphic complex

Ruby metamorphic complex

**Pzrm Marble** (Paleozoic)\-- Massive light- to dark-gray marble and
recrystallized limestone, having sedimentary structures preserved
locally. Age inferred as Devonian and(or) Ordovician by Cass (1959).
Includes the mcl unit of Cass (1959) and the Pzrm and Pztbl units of
Puchner (1984) in the Ruby quadrangle. In the Nulato quadrangle, drill
core at the Illinois Creek prospect yielded Ordovician conodonts (Steve
Teller and Anita Harris, written commun., 1984). Tentatively includes
unit Pzc of Chapman and others (1985) in the Ophir quadrangle which
overlies or maybe gradationally interbedded with quartzite and phyllite
here assigned to unit PzZrqs \[symbol 900+13\] 5340, 8620, unit Pzc,
OP002; unit mcl RB002; unit PzpCc, NL003; unit Pztbl, Pzrm, RB005

**Pzrmi Metamorphosed mafic igneous rocks** (Paleozoic?)\--
Metamorphosed mafic igneous rocks, ranging from metagabbro and
metadiabase to greenstone, amphibolite, and garnet amphibolite. Variable
intensity of sheared within unit. Unit Pzm of Dover (unpublished
mapping, 1997), not mapped separately by Chapman and others (1982)
\[symbol 132+13\] 5285 (new NSAclass)

**MDrao Augen orthogneiss** (Mississippian and(or) Devonian?)\--
Peraluminous granitic gneiss containing augen of potassium feldspar
generally interpreted to represent blastoporphyritic texture. U-Pb
zircon age of 390+/-12 Ma reported from Ray Mountains area of the
(north-central) Tanana quadrangle (Patton and others, 1987); Dillon and
others (1979; 1980 report Middle Devonian to Early Mississippian Rb/Sr
whole-rock and U-Pb zircon ages on similar rocks elsewhere in the Ruby
metamorphic complex. Corresponds to unit MDao of Dover (1994) in the
Tanana quadrangle and some rocks that were included in unit Km of Patton
and others (1978) in the Melozitna quadrangle, which have since been
recognized as augen orthogneiss and included in unit Pzgn of Roeske and
others (1995) \[symbol 184+16\] 6522 (unit Dao, TN003)

**Dm Marble** (Late Devonian)\-- Calcitic to dolomitic marble in
distinctive marker beds intercalated with greenschist and amphibolite
facies rocks of the pelitic and quartz- schist unit (PzZrqs). Age
assignment based on conodonts (Anita Harris, written commun., 1984).
Corresponds to unit Dl of Dover (1994) in the Tanana quadrangle and unit
Pzm of Patton and others (1978) in the Melozitna quadrangle \[symbol
900+14\] 5525, units Dlr, Dld, Ml, TN003; unit Pzm, MZ002

**PzZrqs Pelitic and quartzitic schist** (middle to early Paleozoic
and(or) Late? Proterozoic)\-- Mainly muscovite- and quartz-rich schist,
and subordinate calc-schist, quartzofeldspathic schist, gneiss,
amphibolite, and quartzite. Locally mappable marble interbeds are shown
as unit Dm north of the Kaltag fault and unit Pzrm south of the Kaltag
fault. In the Ray Mountains of the north-central Tanana quadrangle,
underwent polymetamorphic history of synkinematic greenschist, local
blueschist, and amphibolite facies metamorphism that varies depending on
depth of exposure, and proximity to zones of ductile deformation and(or)
buried plutons or other thermal hot spots (Miyaoka and Dover, 1990;
Dover, 1994). Blueschist facies metamorphism largely obliterated by
greenschist to granulite facies overprint in the Kokrines Hills (Roeske
and others, 1995). Includes the Pzs and associated Pzm and MzPzm units
of Dover (1994) in the Tanana quadrangle, the unit PzpCs of Patton and
others (1978), the PzpCm unit of Chapman and Patton (1978), and the Pzs
unit of Roeske and others (1995), in the Melozitna quadrangle. South of
the Kaltag fault, these rocks are even more poorly exposed and
especially little studied rocks. Corresponds to the mc and mca units of
Cass (1959), and the informal PzpCsg and PzpCs units of Puchner (1984)
in the Ruby quadrangle, the PzpCs and PzpCc units of Patton (written
commun., 1997) in the Nulato quadrangle, and the PzpCs unit of Chapman
and others (1986) in the Ophir quadrangle. Unit shown using a vertical
line overprint pattern north of the Kaltag fault and horizontal line
pattern south of the Kaltag fault \[symbol 132+997n, 998s\] 9325 unit
Pzs (Pzqs), TN003; units PzpCs, MZ002; unit PzpCm, RB003; RB004 \[symbol
132+998\] 8650, 8625, 8601, unit PzpCc, PzpCs, NL003; unit PzpCs OP002;
units mc, mca, RB002; unit PzpCsg, PzpCs, RB005,

**PzZrpg Quartzofeldspathic paragneiss and quartzite** (Early Paleozoic
to Proterozoic)\-- Dominantly quartz-rich and quartzofeldspathic
paragneiss, quartzite, and subordinate thinly interlayered quartz-mica
schist, but also contains lenses and layers of augen orthogneiss. In the
Ray Mountains area of the north-central Tanana quadrangle, the unit is
typically well-foliated, and texture ranges from compositionally banded
to massive, depending on composition and grainsize of the protolith
(Dover, 1994). Metamorphosed to amphibolite facies. Undated; appears to
stratigraphically and/or structurally underlie schistose units inferred
as Paleozoic to Late Proterozoic in age. Corresponds to the CZg unit of
Dover (1994) in the Ray Mountains area, part of the PzpCsq unit of
Chapman and others (1982) in the Tanana quadrangle, the PzpCn and PzpCq
units of Patton and others (1978) in the Melozitna quadrangle, and
tentatively, unit Pzpgn of Roeske and others (1995) in the Melozitna
quadrangle and unit PzpCg of Chapman and Patton (1978) in the northwest
Ruby quadrangle. Also tentatively included here, from the western Ruby
quadrangle, Puchner (1984) mapped a pelitic schist and gneiss unit
(PzpCsg) consisting of
quartz-muscovite-chlorite-biotite-graphite-garnet-staurolite schist,
quartzofeldspathic orthogneiss, and foliated greenstone all retrograded
from amphibolite facies. Unit PzpCq of Patton and others (1978) can
alternatively be correlated with unit T[r]{.smallcaps}Mtqp of this map
\[symbol 136\] 8801, 8803 unit PzpCn, MZ002; unit PzZqg, TN003; unit
PzpCg, RB004; unit PzpCsg, RB005

End of Ruby metamorphic complex

Sedimentary rocks

**CZw Wickersham grit, undivided** (Cambrian? and Late Proterozoic)\--
Dominantly clastic sequence of poorly sorted quartzite, feldspathic
quartzite, grit, calcareous siltstone and fine-grained sandstone, and
subordinate dark limestone and chert. Variable cataclasis and generally
low-grade recrystallization, and locally structurally dismembered and
imbricated. Age poorly constrained. Interpreted by F.R. Weber as
protolith of at least part of the quartz- and pelitic schist (PzZyqs)
and schist and amphibolite (PzZysa) units. Includes the CZwg unit of
Weber and others (1992) in the Livengood quadrangle, some rocks of the
PzpCa? and PzpCgq units of Foster and others (1983) in the Circle
quadrangle, the PzPws and PzPwg units of Reifenstuhl and others (1997)
in the Tanana B-1 quadrangle, and rocks tentatively assigned to this
unit in the Kantishna River, Mount McKinley, McGrath, and Medfra
quadrangles (F.R. Weber and T.K. Bundtzen, unpublished data, 1998).
Locally divided into: \[symbol 306\] 8300 unit CZw LG002; unit PzpCa,
CI002; unit Pzw, TN003; unit PzpCs, MG002

**CZwl Wickersham limestone**\-- Medium- to very dark-gray, dense to
very finely crystalline, nonfossiliferous limestone and medium-gray,
fine-grained, non-siliceous dolostone. Dolostone contains nondiagnostic
stromatolites. Interbedded in Wickersham unit. Consists of units Cwl,
CZwl, and CZwad of Weber and others (1992) in the Livengood quadrangle
\[symbol 301+708\] 8000 (unit Cwl, CZwl, CZwad?, LG002)

**CZwa Argillaceous upper unit**\-- Dominantly argillaceous, containing
distinctive tan-weathering gray calcareous siltstone and fine-grained
sandstone, subordinate quartzite and chert, and locally, a few black
clastic limestone interbeds. Corresponds to the CZwa unit of Weber and
others (1992) in the Livengood quadrangle, unit ng of Pewe and others
(1966) in the Fairbanks quadrangle, and the PzpCa unit of Foster and
others (1983) in the Circle quadrangle \[symbol 301\] 8310 unit CZwa,
LG002; unit ng, FB002; unit Cal, TN002

**Zwg Gritty lower unit** (Late Proterozoic?)\-- Dominantly poorly
sorted to bimodal quartzite and gritty quartzite, and granule
conglomerate characteristically containing sparse, single-crystal milky
white to blue quartz granules (\"eyes\") in a slightly cherty
quartzofeldspathic-wacke matrix. Lithologically gradational with
argillaceous upper unit (Czwa). Corresponds to the Zwg unit of Weber and
others (1992) in the Livengood quadrangle, and the PzpCqg unit of Foster
and others (1983) in the Circle quadrangle \[symbol 306+16\] 8410 unit
Zwg, LG002, unit PzpCgq, CI002; unit Cqs KH002

PRECAMBRIAN\
Metamorphic rocks

**ZYnm Metamorphic basement rocks of the Nixon Fork sequence,
undivided** (Late and(or) Middle Proterozoic)\-- Dominantly greenschist
facies quartz- and pelitic schist, with subordinate calc-schist,
quartzofeldspathic schist, marble, schistose felsic metavolcanic rocks,
greenstone, and gneissic and schistose plutonic rocks. Depositionally
overlain by unmetamorphosed Ordovician and latest Cambrian carbonate
rocks of the Nixon Fork sequence in the Medfra quadrangle (Eakins, 1918;
Patton and others, 1980; J.A. Dumoulin and D.C. Bradley, unpublished
data, 1998) and by Permian conglomerate elsewhere (Patton and Dutro,
1979). Kyanite has been reported locally (Grant Abbott and T.K.
Bundtzen, written commun., 1997). Resembles quartz- and pelitic units
(PzZyqs, PzZaqs, and PzZrqs) in the Yukon-Tanana and Ruby crystalline
complexes in the predominance of quartz-mica schist and micaceous
quartzite, but differs from those units in lacking evidence of
Cretaceous or Jurassic metamorphism and in its clear evidence of
pre-Ordovician metamorphism and probable Proterozoic protolith age
(Dillon and others, 1985). K-Ar mica ages ranging from 296-921 Ma are
reported by Silberman and others (1979). Discordant U-Pb zircon ages
from metaplutonic rocks having upper intercepts as old as 1,250+/-50 Ma
and additional K-Ar ages are reported Dillon and others (1985).
Corresponds to one area of the mca unit and the mcb unit of Cass (1959)
in the Ruby quadrangle and a slight extension into the Medfra quadrangle
based on mapping of Eakin (1918). Locally (primarily the Medfra
quadrangle), subdivided into: \[symbol 133+995\] 8600 unit mcb, RB002
(and slight extension into Medfra)

**ZYns Pelitic schist**\-- Chiefly greenschist facies pelitic schist and
quartzose metasedimentary rocks, with subordinate calc-schist, marble,
and locally, greenstone (Patton and others, 1980). Includes a small
granitic gneiss body in the Medfra quadrangle. Stratigraphic evidence
indicates a pre-Ordovician age; K-Ar mica minimum ages range between 274
and 514 Ma (Silberman and others, 1979). Corresponds to unit PzpCp of
Patton and others (1980) \[symbol 133+15\] 8640 unit PzpCp, MD002

**ZYnc Calc-schist**\-- Dominantly light- to medium-gray calc-schist and
thin-bedded schistose marble, and subordinate quartz-mica schist.
Gradational into pelitic schist unit (ZYns). Distinguished from pelitic
schist in poorly exposed areas by relatively smooth aeromagnetic
signature in contrast to rugged, steep-gradient profiles over pelitic
schist unit (Patton and others, 1980). Corresponds to PzpCc unit of
Patton and others (1980) \[symbol 133+708\] 8610 unit PzpCc, MD002

**ZYnv Metavolcanic rocks**\-- Tan, light-gray, pink, and green banded
fine-grained blastoporphyritic felsic metavolcanic rocks having a
well-developed foliation. Subordinate quartzofeldspathic rocks thought
to represent recrystallized felsic flows and tuffs (Patton and others,
1980). Corresponds to the PzpCv unit of Patton and others (1980)
\[symbol 133+16\] 8700 unit PzpCv, MD002

**Ynqd Meta-quartz diorite** (middle Proterozoic?)\-- Sheared
metamorphosed porphyritic quartz diorite. Contains biotite phenocrysts
as large as 1 cm and numerous micro-veinlets of quartz (Silberman and
others, 1979). K-Ar age on biotite yielded an age of 921+/-25 Ma and
muscovite from mylonite along border yielded 663+/-20 Ma (Silberman and
others, 1979). Intrudes quartz-mica schist of unit ZYnm in the southwest
Ruby quadrangle. Corresponds to unit pCm of Silberman and others (1979)
\[symbol 133+348\] unit 8710 (new nsaclass) unit pCm, RB007

**Xi Idono metamorphic complex** (Early Proterozoic)\-- Foliated augen
gneiss, amphibolite, and minor metasedimentary rocks, all of amphibolite
facies. Protolith age 2.06 Ga based on U-Pb zircon and Sm-Nd isotopic
dating of Miller and others (1991); K-Ar ages range from 120 to 1230 Ma.
Corresponds to unit Xi of Miller and Bundtzen (1994) \[symbol 187\] 9400

References cited

Aleinikoff, J.N., Dusel-Bacon, C., and Foster, H.L.., 1986,
Geochronology of augen gneiss and related rocks, Yukon-Tanana terrane,
east-central Alaska: Geological Society of America Bulletin v. 97, p.
626-637.

Aleinikoff, J.N., Moore, T.E., Nokleberg, W.J., and Koch, R.D., 1995,
Preliminary U-Pb ages from detrital zircons from the Arctic Alaska and
Yukon-Tanana terranes, Alaska: Geological Society of America Abstracts
with Programs v 27, p. 2

Aleinikoff, J.N., and Nokleberg, W.J., 1989, Age of deposition and
provenance of the Fairbanks Schist unit, Yukon-Tanana terrane,
east-central Alaska: U.S. Geological Survey Bulletin 1903, p. 75-83.

Berg, H.C., Jones, D.L., and Richter, D.H., 1972, Gravina-Notzutin belt
\-- Tectonic significance of an upper Mesozoic sedimentary and volcanic
sequence in southern and southeastern Alaska, *in* Geological Survey
research 1972: U.S. Geological Survey Professional Paper 800-D, p.
D1-D24.

Blodgett, R.B., and Brease, P.F., 1997, Essian (late Early Devonian)
brachiopods from Shellabarger Pass, Talkeetna C-6 quadrangle, Denali
National Park, Alaska indicate Siberian origin for Farewell terrane
\[abs.\]: Geological Society of America Abstracts with Program, v. 29,
no. 5, p. 5.

Box, S.E., Moll-Stalcup, E.J., Frost, T.P., and Murphy, J.M., 1993,
Preliminary geologic map of the Bethel and southern Russian Mission
quadrangles, southwestern Alaska: U.S. Geological Survey Miscellaneous
Field Studies Map MF-2226-A, scale 1:250,000.

Brabb, E.E., 1969, Six new Paleozoic and Mesozoic Formations in
east-central Alaska: U.S. Geological Survey Bulletin 1274-I, p. I1-I26.

Brabb, E.E., and Churkin, Michael, Jr., 1969, Geologic map of the
Charley River quadrangle, east-central Alaska: U.S. Geological Survey
Miscellaneous Geologic Investigations Map I-573, scale 1:250,000.

Brosge, W.P., Lanphere, M.A., Reiser, H.N., and Chapman, R.M., 1969,
Probable Permian age of the Rampart Group, central Alaska: U.S.
Geological Survey Bulletin 1294-B, 18 p.

Bundtzen, T.K., 1981, Geology and mineral deposits of the Kantishna
Hills, Mount McKinley quadrangle, Alaska: Fairbanks, University of
Alaska, M.S. Thesis, 237 p., 1 sheet, scale 1:63,360.

Bundtzen, T.K., and Laird, G.M., 1980, Preliminary geology of the
McGrath-upper Innoko River area, western Interior Alaska: Alaska
Division of Geological and Geophysical Surveys, Open-File Report 134, 36
p., 3 plates.

Bundtzen, T.K., and Laird, G.M., 1982, Geologic map of the Iditarod D-2
and western D-3 quadrangles, Alaska: Alaska Division of Geological and
Geophysical Surveys, Professional Report 72, 1 plate.

Bundtzen, T.K., Harris, E.E., and Gilbert, W.G., 1997a, Geologic map of
the eastern half of the McGrath quadrangle, Alaska: Alaska Division
Geological and Geophysical Surveys Report of Investigations 97-14a,
scale 1:125,000, 34 p.

Bundtzen, T.K., Pinney, D.S., and Laird, G.M., 1997b, Preliminary
geologic map and data table from the Ophir C-1 and western Medfra C-6
quadrangles, Alaska: Alaska Division Geological and Geophysical Surveys
Public Data File 97-46, scale 1:63,360, 10 p.

Bundtzen, T.K., Laird, G.M., Clautice, K.H., and Harris, E.E., 1994,
Geologic map of the Gagaryah River area, Lime Hills C-5 and C-6
quadrangles, southwest Alaska: Alaska Division Geological and
Geophysical Surveys Public Data File 94-40, scale 1:63,360.

Calderwood, K.W., and Fackler, W.C., 1972, Proposed stratigraphic
nomenclature for Kenai Group, Cook Inlet basin, Alaska, American
Association of Petroleum Geologists Bulletin, v. 56, no. 4, p. 739-754.

Carden, J.R., Connelly, W., Forbes, R.B., and Turner, D.L., 1977,
Blueschists of the Kodiak Islands, Alaska: An extension of the Seldovia
schist terrane: Geology, v. 5, p. 529-533.

Cass, J.T., 1959, Reconnaissance geologic map of the Ruby quadrangle,
Alaska: U.S. Geological Survey Miscellaneous Investigation Map I-289, 1
sheet, scale 1:250:000.

Chapman, R.M., and Patton, W.W., Jr., 1978, Preliminary summary of the
geology in the northwest part of the Ruby quadrangle, *in* Johnson,
K.M., ed., The United States Geological Survey in Alaska:
Accomplishments during 1977: U.S. Geological Survey Circular 772-B, p.
B39-B41.

Chapman, R.M., and Patton, W.W., Jr., 1979, Two upper Paleozoic rock
units identified in southwestern part of the Ruby quadrangle, *in*
Johnson, K.M., and Williams, J.R., eds., The United States Geological
Survey in Alaska: Accomplishments during 1978: U.S. Geological Survey
Circular 804-B, p. B59-B61.

Chapman, R.M., Patton, W.W., Jr., and Moll, E.J., 1985, Reconnaissance
geology of the Ophir quadrangle, Alaska: U.S. Geological Survey
Open-File Report 85-203, 17 p., 1 sheet, scale 1:250,000.

Chapman, R.M., Yeend, W.E., Brosge, W.P, and Reiser, H.N., 1975,
Preliminary geologic map of the Tanana and northeast part of the
Kantishna River quadrangles, Alaska: U.S. Geological Survey Open File
Report 75-337, scale 1:250,000.

Chapman, R. M., Patton, W. W. Jr., and Moll, E. J., 1985, Reconnaissance
geologic map of the Ophir quadrangle, Alaska: U.S. Geological Survey
Open-File Report 85-203, 1 sheet, scale 1:250,000.

Chapman, R.M., Yeend, W.E., Patton, W.W., Jr., 1975, Preliminary
reconnaissance geologic map of the western half of Kantishna River
quadrangle, Alaska: U.S. Geological Survey Open File Report 75-351,
scale 1:250,000.

Chapman, R.M., Yeend, Warren, Brosge, W.P., and Reiser, H.N., 1982,
Reconnaissance geologic map of the Tanana quadrangle, Alaska: U.S.
Geological Survey Open-File Report 82-734, scale 1:250,000, 18 p.

Churkin, Michael, Jr., and Carter, Claire, 1996, Stratigraphy,
structure, and graptolites of an Ordovician and Silurian sequence in the
Terra Cotta Mountains, Alaska Range, Alaska: U.S. Geological Survey
Professional Paper 1555, 84 p.

Churkin, M., Jr., Foster, H.L., Chapman, R.M., and Weber, F.R., 1982,
Terranes and suture zones in east-central Alaska: Journal of Geophysical
Research, v. 87, no. B5, p. 3718-3730.

Clark, S.H.B., 1972, Reconnaissance bedrock geologic map of the Chugach
Mountain near Anchorage, Alaska: U.S. Geological Survey Miscellaneous
Field Studies Map MF-350, 1 sheet, scale 1:250,000.

Coney, P.J., and Jones, D.L., 1985, Accretion tectonics and crustal
structure in Alaska: Tectonophysics, v. 119, p. 265-283.

Cowan, D.S., and Boss, R.F., 1978, Tectonic framework of the
southwestern Kenai Peninsula, Alaska: Geological Society of America
Bulletin, v. 89, p. 155-158.

Csejtey, Bela, Jr., Mullen, M.W., Cox, D.P., and Stricker, G.D., 1992,
Geology and geochronology of the Healy quadrangle, south-central Alaska:
U.S. Geological Survey Miscellaneous Investigations Series Map I-1961,
scale 1:250,000, 63 p.

Csejtey, Bela, Jr., Nelson, W.H., Eberlein, G.D., Lanphere, M.A., and
Smith, J.G., 1977, New data concerning age of the Arkose Ridge
Formation, south-central Alaska in Blean, K.M., ed., The United States
Geological Survey in Alaska: Accomplishments during 1976: U.S.
Geological Survey Circular 751-B, p. B62-B64.

Csejtey, Bela, Jr., Nelson, W.H., Jones, D.L., Silberling, N.J., Dean,
R.M., Morris, M.S., Lanphere, M.A., Smith, J.G., and Silberman, M.L.,
1978, Reconnaissance geologic map and geochronology, Talkeetna Mountains
quadrangle, northern part of Anchorage quadrangle, and southwest corner
Healy quadrangle, Alaska: U.S. Geological Survey Open-file Report
78-558A, scale 1:250,000, 60 p.

Decker, John, Bergman, S.C., Blodgett, R.B., Box, S.E., Bundtzen, T.K.,
Clough, J.G., Coonrad, W.L., Gilbert, W.G., Miller, M.L., Murphy, J.M.,
Robinson, M.S., and Wallace, W.K., 1994, Geology of southwestern Alaska,
*in* Plafker, George and Berg, H.C., eds., The Geology of Alaska, volume
G-1, The Geology of North America: Geological Society of America, Decade
of North American Geology, p. 285-310.

Detterman, R.L., and Reed, B.L., 1980, Stratigraphy, structure, and
economic geology of the Iliamna quadrangle, Alaska: U.S. Geological
Survey Bulletin 1368-B, 86 p., 1 sheet, scale 1:250,000.

Detterman, R.L., Case, J.E., Miller, J.W., Wilson, F.H., and Yount,
M.E., 1996, Stratigraphic Framework of the Alaska Peninsula, *in*
Geologic Studies on the Alaska Peninsula: U.S. Geological Survey
Bulletin 1969-A, 74 p.

Dillon, J.T., Pessel, G.H., Chen, J.H., and Veach, N.C., 1979, Tectonic
and economic significance of Late Devonian and late Proterozoic U-Pb
zircon ages from the Brooks Range, Alaska: Alaska Division of Geological
and Geophysical Surveys Geologic Report 61, p. 36-43.

Dillon, J.T., Pessel, G.H., Chen, J.H., and Veach, N.C., 1980, Middle
Paleozoic magmatism and orogenesis in the Brooks Range, Alaska: Geology,
v. 8, p. 338-343.

Dillon, J.T., Patton, W.W., Jr., Mukasa, S.B., Tilton, J.B., and Moll,
E.J., 1985, New radiometric evidence for the age and thermal history of
the metamorphic rocks of the Ruby and Nixon Fork terranes, west-central
Alaska, *in* Bartsch-Winkler, S., and Reed, K.M., eds., The United
States Geological Survey in Alaska: Accomplishments during 1983: U.S.
Geological Survey Circular 945, p. 13-18.

Dillon, J.T., Brosge, W.P., and Dutro, J.T., Jr., 1986, Generalized
geologic map of the Wiseman quadrangle, Akaska: U.S. Geological Survey
Open-File Report 86-219, scale 1:250,000.

Dover, J.H., 1994, Geology of part of east-central Alaska, *in* Plafker,
George and Berg, H.C., eds., The Geology of Alaska, volume G-1, The
Geology of North America: Boulder, Colorado, Geological Society of
America, Decade of North American Geology, p. 153-204.

Dover, J.H., and Miyaoka, R.T., 1988, Reinterpreted geologic map and
fossil data, Charley River quadrangle, east-central, Alaska:: U.S.
Geological Survey Miscellaneous Field Studies Map MF-2004, scale
1:250,000.

DuBois, G.D., Wilson, F.H., and Shew, Nora, 1986, Map and table showing
potassium-argon age determinations and selected major-element chemical
analyses from the Circle quadrangle, Alaska: U.S. Geological Survey
Open-File Report 86-392, scale 1:250,000.

Dumoulin, J.A., Bradley, D.C., and Harris, A.G., in press,
Sedimentology, conodonts, structure, and correlation of Silurian and
Devonian metasedimentary rocks in Denali National Park, Alaska *in*
Gray, J. and Riehle, J.R. , eds., Geologic studies in Alaska by the U.S.
Geological Survey in 1996, U.S. Geological Survey Professional Paper, 50
MS pp, 12 figs.

Dusel-Bacon, Cynthia, 1994, Metamorphic history of Alaska, *in* Plafker,
G., and Berg, H.C., eds., The Geology of Alaska: Boulder, Colorado,
Geological Society of America, The Geology of North America v G-1, p.
495-533.

Dusel-Bacon, Cynthia, and Aleinikoff, J.N., 1985, Petrology and tectonic
significance of augen gneiss from a belt of Mississippian granitoids in
the Yukon-Tanana terrane, east-central Alaska: Geological Society of
America Bulletin, v. 96, p. 411-425.

Dusel-Bacon, Cynthia, and Aleinikoff, J.N., 1996, U-Pb zircon and
titanite ages for augen gneiss from the Divide Mountain area, eastern
Yukon-Tanana upland, Alaska, and evidence for the composite nature of
the Fiftymile batholith, *in* Moore, T.E., and Dumoulin, J.A., eds.
Geologic Studies in Alaska by the U.S. Geological Survey during 1994:
U.S. Geological Survey Bulletin 2152, p. 131-141.

Dusel-Bacon, Cynthia, and Foster, H.L., 1983, A sillimanite gneiss dome
in the Yukon crystalline terrane, east-central Alaska; petrography and
garnet-biotite thermometry: U.S. Geological Survey Professional Paper
1179-E, 25 p.

Dusel-Bacon, Cynthia, Brosge, W.P., Till, A.B., Doyle, E.O., Mayfield,
C.F., Reiser, H.N., and Miller, T.P., 1989, Distribution, facies, ages,
and proposed tectonic associations of regionally metamorphosed rocks in
northern Alaska: U.S. Geological Survey Professional Paper 1497-A, 44
p., 2 plates., 1:1,000,000-scale.

Dusel-Bacon, Cynthia, Csejtey, B., Jr., Foster, H.L., Doyle, E.O.,
Nokleberg, W.J., and Plafker, George, 1993, Distribution, facies, ages,
and proposed tectonic associations of regionally metamorphosed rocks in
east- and south-central Alaska: U.S. Geological Survey Professional
Paper 1497-C, 73 p., 2 plates., 1:1,000,000-scale.

Dusel-Bacon, Cynthia, Wooden, J.L., Mortensen, J.K., Bressler, J.R.,
Takaoka, Hidetoshi, Oliver, D.H., Newberry, Rainer, and Bundtzen, T.K.,
1998, Metamorphic-hosted mineralization in the Yukon-Tanana Upland,
Alaska \[extended abs.\]: Alaska Miners Association, Extended abstracts
of the 16th Biennial Conference on Alaskan Mining, \"Second Rush of
98\", p. 16-18.

Dutro, J.T., Jr., and Patton, W.W., Jr., 1982, New Paleozoic formations
in the northern Kuskokwim Mountains, west-central Alaska, *in*
Stratigraphic notes, 1980-1982: U.S. Geological Survey Bulletin 1529-H,
p. H13-H22.

Eakin, H.M., 1918, The Cosna-Nowitna region, Alaska: U.S. Geological
Survey Bulletin 667, map, scale 1:250,000, 54 p.

Forbes, R.B., 1982, with contributions from F.R. Weber, R.C. Swainbank,
J.M. Britton, and J.M. Brown, Bedrock geology and petrology of the
Fairbanks Mining District: Alaska Division of Geological and Geophysical
Surveys Open-file Report AOF-169, 68 p.

Foster, H.L., Laird, Jo, Keith, T.E.C., Cushing, G.W., and Menzie, W.D.,
1983, Preliminary geologic map of the Circle quadrangle, Alaska: U.S.
Geological Survey Open-File Report, 83-170-A, scale 1:250,000.

Foster, H.L., Keith, T.E.C., and Menzie, W.D., 1994, Geology of the
Yukon-Tanana area of east-central Alaska, *in* Plafker, G., and Berg,
H.C., eds., The Geology of Alaska: Boulder, Colorado, Geological Survey
of America, The Geology of North America, v. G-1, p. 205-240.

Galloway, J.P., and Laney, Jim, 1994, Status of geologic mapping in
Alaska \-- A digital bibliography: U.S. Geological Survey Open-File
Report OFR 94-675-A, 96 p., 4 plates, scale 1:7,500,000.

Gamble, B.M., and Reed, B.L., 1996, Preliminary geologic map of the
eastern half of the Lime Hills quadrangle, Alaska: unpublished U.S.
Geological Survey map compilation, scale 1:250,000.

Gemuts, I., Puchner, C.C., and Steffel, C.I., 1983, Regional geology and
tectonic history of western Alaska *in* Proceedings of the 1982
Symposium on Western Alaska Geology and Resource Potential: Journal of
the Alaska Geological Society v. 3, p. 67-85.

Gilbert, W.G., 1979, A geologic guide to Mount McKinley National Park:
Alaska Natural History Association, in cooperation with the National
Park Service, U.S. Dept. of the Interior, 52 p., 1 plate, scale
1:250,000.

Gilbert, W.G., 1981, Preliminary geologic map of Cheeneetuk River area,
Alaska: Alaska Division of Geological and Geophysical Survey Open File
Report AOF-153, scale 1:63,360.

Gilbert, W.G., and Redman, E.R., 1977, Metamorphic rocks of the
Toklat-Teklanika River area, Alaska: Alaska Division of Geological and
Geophysical Surveys Geologic Report 50, 30 p., 1 sheet, scale 1:63,360.

Grantz, Arthur, 1960, Geologic map of the Talkeetna A-2 quadrangle,
Alaska and contiguous area to the north and northwest: U.S. Geological
Survey Miscellaneous Investigations Series Map I-313, scale 1:48,000.

Hoare, J.M., and Coonrad, W.L., 1959a, Geology of the Bethel quadrangle,
Alaska: U.S. Geological Survey Miscellaneous Investigations Series Map
I-285, scale 1:250,000.

Hoare, J.M., and Coonrad, W.L., 1959b, Geology of the Russian Mission
quadrangle, Alaska: U.S. Geological Survey Miscellaneous Investigations
Series Map I-292, scale 1:250,000.

Imlay, R.W., and Reeside, J.B., Jr., 1954, Correlation of the Cretaceous
formations of Greenland and Alaska: Geological Society of America
Bulletin, v. 65, p. 223-246.

Jones, D.L., and Silberling, N.J., 1979, Mesozoic stratigraphy: The key
to tectonic analysis of southern and central Alaska: U.S. Geological
Survey Open-File Report 79-2100, 41 p.

Jones, D.L., Silberling, N.J., and Hillhouse, John, 1977, Wrangellia \--
a displaced terrane in northwestern North America: Canadian Journal of
Earth Sciences, v. 14, no. 11, p. 2565-2577.

Jones, D.L., Silberling, N.J., Gilbert, W.G., and Coney, P.J.,, 1982,
Character, distribution, and tectonic significance of accretionary
terranes in the central Alaska Range: Journal of Geophysical Research,
v. 87, no. B5, p. 3709-3717.

Kelley, J.S., 1984, Geologic map and sections of the southwestern Kenai
Peninsula west of the Port Graham fault: U.S. Geological Survey
Open-File Report 84-152, scale 1:63,360.

Layer, P.W. and Solie, D.N., 1991, Timing of igneous activity and basin
formation, southern Alaska Range, as constrained by 40Ar/39Ar dating:
EOS, v. 72, no. 44, p. 503.

Loney, R.A., and Himmelberg, G.R., 1985, Distribution and character of
the peridotite-layered gabbro complex of the southeastern Yukon-Koyukuk
ophiolite belt, Alaska, *in* Bartsch-Winkler, S., and Reed, K.M., eds.,
U.S. Geological Survey in Alaska; Accomplishments during 1983: U.S.
Geological Survey Circular 945, p. 46-48

MacKevett, Jr., E.M., 1978, Geologic map of the McCarthy quadrangle,
Alaska: U.S. Geological Survey Miscellaneous Investigations Series Map
I-1032, scale 1:250,000.

MacKevett, E.M., Jr., and Plafker, George, 1974, The Border Ranges fault
in south-central Alaska: U.S. Geological Survey Journal of Research, v.
2, no. 3, p. 323-329.

Magoon, L.B. Adkison, W.L., and Egbert, R.M, 1976, Map showing geology,
wildcat wells, Tertiary plant localities, K/Ar age dates, and petroleum
operations, Cook Inlet area, Alaska: U.S. Geological Survey
Miscellaneous Investigations Series Map I-1019, scale 1:250,000, 3
sheets.

Mamay, S.H., and Reed, B.L., 1984, Permian plant megafossils from the
conglomerate of Mt. Dall, central Alaska Range, *in* Coonrad, W.L., and
Elliott, R.L., eds., United States Geological Survey in Alaska;
Accomplishments during 1981: U.S. Geological Survey Circular 868, p.
98-102.

Martin, G.C., 1926, The Mesozoic stratigraphy of Alaska: U.S. Geological
Survey Bulletin 776, 493 p.

Mertie, J.B., Jr., and Harrington, G.L., 1924, The Ruby-Kuskokwim
region, Alaska: U.S. Geological Survey Bulletin 754, 129 p.

Meyer, J.F., Jr., and Saltus, R.W., 1995, Merged aeromagnetic map of
Interior Alaska: U.S. Geological Survey Geophysical Investigations Map
GP-1014, 2 sheets, scale 1:500,000.

Meyer, J.F., Jr., Saltus, R.W., Barnes, D.F., and Morin, R.F., 1996,
Bouguer gravity map of Interior Alaska: U.S. Geological Survey
Geophysical Investigations Map GP-1016, 2 sheets, scale 1:500,000.

Miller, M.L, and Bundtzen, T.K., 1994, Generalized geologic map of the
Iditarod quadrangle, Alaska, showing potassium-argon, major-oxide,
trace-element, fossil, paleocurrent, and archaeological sample
localities: U.S. Geological Survey Miscellaneous Field Studies Map
MF-2219A, scale 1:250,000, 48 p.

Miller, M.L., Belkin, H.E., Blodgett, R.B., Bundtzen, T.K., Cady, J.W.,
Goldfarb, R.J., Gray, J.E., McGimsey, R.G., and Simpson, S.L., 1989,
Pre-field study and mineral resource assessment of the Sleetmute
quadrangle, southwestern Alaska: U.S. Geological Survey Open-File Report
89-363, 115 p., 1 map, scale 1:250,000.

Miller, M.L., Bradshaw, J.Y., Kimbrough, D.L., Stern, T.W., and
Bundtzen, T.K., 1991, Isotopic evidence for Early Proterozoic age of the
Idono Complex, west-central Alaska: Journal of Geology, v. 99, no. 2, p.
209-223.

Miller, T.P., and Smith, R.L., 1976, \"New\" volcanoes in the Aleutian
volcanic arc, *in* Cobb, E.H., ed., The United States Geological Survey
in Alaska: Accomplishments during 1975: U.S. Geological survey Circular
733, p. 11.

Miyaoka, R.T., and Dover, J.H., 1990, Shear sense in mylonites, and
implications for transport of the Rampart assemblage (Tozitna terrane),
Tanana quadrangle, east-central Alaska, *in* Dover, J.H., and Galloway,
J.P., eds., Geologic studies in Alaska by the U.S. Geological Survey,
1989: U.S. Geological Survey Bulletin 1946, p. 51-64.

Moll-Stalcup, Elizabeth, Brew, D.A., and Vallier, T.L., 1994, Latest
Cretaceous and Cenozoic magmatic rocks of Alaska, Plate 5, in Plafker,
George and Berg, H.C., eds., The Geology of Alaska, The Geology of North
America, Volume G-1: Geological Society of America Decade of North
America Geology Project, 1 sheet, scale 1:2,500,000.

Mortensen, J.K., 1992, Pre-mid-Mesozoic tectonic evolution of the
Yukon-Tanana terrane, Yukon and Alaska: Tectonics v. 11, p. 836-853.

Newberry, R.J., Bundtzen, T.K, Clautice, K.H., Combellick, R.A.,
Douglas, T., Laird, G.M., Liss, S.A., Pinney, D.S., Reifenstuhl, R.R.,
and Solie, D.N., 1996, Preliminary geologic map of the Fairbanks Mining
District, Alaska: Alaska Division of Geological and Geophysical Surveys
Public Data File 96-16, scale ?, ? p.

Nokleberg, W.J., Aleinikoff, J.N., Lange, I.M., Silva, S.R., Miyaoka,
R.T., Schwab, C.E., and Zehner, R.E., with contribution for selected
areas from Bond, G.C., Richter, D.H., Smith, T.E., and Stout, J.H.,
1992a, Preliminary geologic map of the Mount Hayes quadrangle, eastern
Alaska Range, Alaska: U.S. Geological Survey Open-File Report 92-594,
scale 1:250,000.

Nokleberg, W.J., Aleinikoff, J.N., Dutro, J.T., Jr., Lanphere, M.A.,
Silberling, N.J., Silva, S.R., Smith, T.E., and Turner, D.L., 1992b,
Map, tables, and summary of fossil and isotopic age data, Mount Hayes
quadrangle, eastern Alaska Range, Alaska: U.S. Geological Survey Map
MF-1996-D, scale 1:250,000, 43 p.

Nokleberg, W.J., Moll-Stalcup, E.J., Miller, T.P., Brew, D.A., Grantz,
Arthur, Reed, J.C., Jr., Plafker, George, Moore, T.E., Silva, S.R., and
Patton, W.W., Jr., 1994, Tectonostratigraphic terrane and overlap
assemblage map of Alaska: U.S. Geological Survey Open-File Report
94-194, 45 p., scale 1:2,500,000.

Nokleberg, W.J., Richter, D.H., Ferrians, O.J., Lange, I.M., Campbell,
D.L., Aleinikoff, J.N., Smith, T.E., and Koch, R.D., in press,
Introduction, previous studies, acknowledgements, detailed description
of map units, geologic and tectonic summary, and references cited for
preliminary geologic map of the Gulkana quadrangle, eastern Alaska Range
and northern Copper River Basin, Alaska: U.S. Geological Survey
Open-File Report, scale 1:250,000, text 32 p.

Paige, Sidney, and Knopf, Adolph, 1907, Stratigraphic succession in the
region northeast of Cook Inlet, Alaska: Geological Society of America
Bulletin, v. 18, p. 327-328.

Patton, W.W., Jr., 1966, Regional geology of the Kateel River
quadrangle, Alaska: U.S. Geological Survey Miscellaneous Geologic
Investigations Map I-437, scale 1:250,000.

Patton, W.W., Jr., 1973, Reconnaissance geology of the northern
Yukon-Koyukuk province, Alaska: U.S. Geological Survey Professional
Paper 774-A, p. A1-A17.

Patton, W.W., Jr., and Dutro, J.T., Jr., 1979, Age of the metamorphic
complex in the northern Kuskokwim Mountains, west-central Alaska, *in*
Johnson, K.M., and Williams, J.R., eds., The United States Geological
Survey in Alaska: Accomplishments during 1978: U.S. Geological Survey
Circular 804-B, p. B61-B63

Patton, W.W., Jr., and Miller, T.P., 1973, Bedrock geologic map of
Bettles and southern part of Wiseman quadrangles, Alaska: U.S.
Geological Survey Miscellaneous Field Studies Map MF-492, scale
1:250,000.

Patton, W.W., Jr., and Moll-Stalcup, E.J., 1996, Geologic map of the
Unalakleet quadrangle, west-central Alaska: U.S. Geological Survey
Miscellaneous Investigations Series Map I-2559, scale 1:250,000, 39 p.

Patton, W.W., Jr., Box, S.E., Moll-Stalcup, E.J., and Miller, T.P.,
1994a, Geology of west-central Alaska *in* Plafker, George, and Berg,
H.C., eds., The Geology of Alaska: Geological Society of America, The
Geology of North America, Boulder, Colorado, v. G-1, p. 241-269.

Patton, W.W., Jr., Box, S.E., and Grybeck, D.J.,, 1994b, Ophiolites and
other mafic-ultramafic complexes in Alaska *in* Plafker, George, and
Berg, H.C., eds., The Geology of Alaska: Geological Society of America,
The Geology of North America, Boulder, Colorado, v. G-1, p. 671-686.

Patton, W.W., Miller, T.P., Chapman, R.M., and Yeend, Warren, 1978,
Geologic map of the Melozitna quadrangle, Alaska: U.S. Geological Survey
Miscellaneous Geologic Investigations Map I-1071, scale 1:250,000.

Patton, W.W., Jr., Moll, E.J., Dutro, J.T., Jr., Silberman, M.L., and
Chapman, R.M., 1980, Preliminary geologic map of the Medfra quadrangle,
Alaska: U.S. Geological Survey Open-File Report 80-811A, 1 sheet, scale
1:250,000.

Patton, W.W., Jr., Stern, T.W., Arth, J.G., and Carlson, C., 1987, New
U/Pb ages from granite and granite gneiss in the Ruby geanticline and
southern Brooks Range, Alaska: Journal of Geology v. 95, p. 118-126.

Patton, W.W., Jr., Tailleur, I.L., Brosge, W.P., and Lanphere, M.A.,
1977, Preliminary report on the ophiolites of northern and western
Alaska, *in* Coleman, R.G., and Irwin, W.P., North American Ophiolites:
Oregon Department of Geology and mineral Industries, Bulletin 95, p.
51-57.

Patton, W.W., Jr., Moll, E.J., Lanphere, M.A., and Jones, D.L., 1984,
New age data for the Kaiyuh Mountains, west-central Alaska, *in*
Coonrad, W.L., and Elliott, R.L., eds., United States Geological Survey
in Alaska; Accomplishments during 1981: U.S. Geological Survey Circular
868, p. 30-32.

Pewe, T.L., Wahrhaftig, C., and Weber, F., 1966, Geologic map of the
Fairbanks quadrangle, Alaska: U.S. Geological Survey, Miscellaneous
Investigations I-455, 5 pages, 1 sheet, scale 1:250,000.

Plafker, George, Lull, J.S., Nokleberg, W.J., Pessel, G.H., Wallace,
W.K., and Winkler, G.R., 1992, Geologic map of the Valdez A-4, B-3, B-4,
C-3, C-4, D-4 quadrangles, northern Chugach Mountains and southern
Copper River basin: U.S. Geological Survey Miscellaneous Investigations
Series Map I-2164, 1 sheet, scale 1:125,000.

Puchner, C.C., 1984, Geologic map of the Ruby/Poorman area: Unpublished
Anaconda Mining Company Report, scale 1:250,000

Reed, B.L., and Gamble, B.M., 1988, Preliminary geologic map of the Lime
Hills quadrangle, Alaska, *in* Gamble, B.M., Allen, M.S., McCammon,
R.B., Root, D.H., Scott, W.A., Griscom, Andrew, Krohn, M.D., Ehmann,
W.J., and Southworth, S.C., Lime Hills quadrangle, Alaska \-- An AMRAP
planning document: U.S. Geological Survey Administrative report, 167 p.,
22 plates.

Reed, B.L, and Elliott, R.L., 1970, Reconnaissance geologic map,
analyses of bedrock and stream sediment samples, and an aeromagnetic map
of parts of the southern Alaska Range: U.S. Geological Survey Open File
Report 70-271, scale 1:63,360, 24 p.

Reed, B.L., and Lanphere, M.A., 1969, Age and chemistry of Mesozoic and
Tertiary plutonic rocks in south-central Alaska: Geological Society of
America Bulletin, v. 80, p. 23-44.

Reed, B.L., and Lanphere, M.A., 1972, Generalized geologic map of the
Alaska-Aleutian Range batholith showing potassium-argon age of the
plutonic rocks: U.S. Geological Survey Miscellaneous Field Studies Map
MF-372, 2 sheets, scale 1:1,000,000.

Reed, B.L., and Lanphere, M.A., 1973, Alaska-Aleutian Range batholith
\-- Geochronology, chemistry, and relation to circum-Pacific plutonism:
Geological Society of America Bulletin, v. 84, p. 2583-2610.

Reed, B.L., and Nelson, S.W., 1980, Geologic map of the Talkeetna
quadrangle, Alaska: U.S. Geological Survey, Miscellaneous Investigation
Series Map I-1174, 15 pages, 1 plate, scale 1:250,000.

Reifenstuhl, R.R., Dover, J.H., Pinney, D.S., Newberry, R.J., Clautice,
K.H., Liss, S.A., Blodgett, R.B., Bundtzen, T.K., and Weber, F.R., 1997,
Geologic map of the Tanana B-1 quadrangle, central Alaska: Alaska
Department of Geological and Geophysical Surveys Report of
Investigations 97-15a, scale 1:63,360, 17 p.

Reifenstuhl, R.R., Dover, J.H., Newberry, R.J., Clautice, K.H., Liss,
S.A., Blodgett, R.B., and Weber, F.R., 1998, Geologic map of the Tanana
A-1 and A-2, central Alaska: Alaska Department of Geological and
Geophysical Surveys Public Data File 98-37a, scale 1:63,360.

Ridgeway, K.D, Trop, J.M., and Sweet, A.R., 1994, Depositional systems,
age, and provenance of the Cantwell Formation, Cantwell basin, Alaska
Range \[abs\]: Geological Society of America Abstracts with Programs, v.
26, p. 492.

Riehle, J.R., Fleming, M.D., Molnia, B.F., Dover, J.H., Kelley, J.S.,
Miller, M.L., Nokleberg, W.J., Plafker, George, and Till, A.B., 1997,
Digital shaded-relief image of Alaska: U.S. Geological Survey
Miscellaneous Investigations Series Map I-2585, scale 1:2,500,000.

Robinson, M.S., Smith, T.E., and Metz, P.A., 1990, Bedrock geology of
the Fairbanks Mining District: Alaska Division of Geological and
Geophysical Surveys Professional Report 106, scale 1:63,360.

Roeske, S.M., 1986, Field relations and metamorphism of the Raspberry
Schist, Kodiak Island, Alaska, *in* Evans, B.W., and Brown, E.H., eds.,
Blueschist and ecologites: Geological Society of America Memoir 164, p.
169-184.

Roeske, S.M., Mattinson, J.M., and Armstrong, R.L., 1989, Isotopic ages
of glaucophane schists on the Kodiak Islands, southern Alaska, and their
implications for Mesozoic tectonic history of the Border Ranges Fault
system: Geological Society of America Bulletin, v. 101, p. 1021-1037.

Roeske, S.M., Dusel-Bacon , C., Aleinikoff, J.N., Snee, L.W., and
Lanphere, M.A., 1995, Metamorphic and structural history of continental
crust at a Mesozoic collisional margin, the Ruby terrane, central
Alaska: Journal of Metamorphic Geology v. 13, p. 25-40.

St. John, J.M., and Babcock, L.E., 1997, Middle Cambrian trilobites of
Siberian aspect from the Farewell terrane, southwestern Alaska: U.S.
Geological Survey Professional Paper 1574, p. 269-281.

Silberling, N.J., and Jones, D.L., eds., 1984, Lithotectonic terrane
maps of the North American Cordillera: U.S. Geological Survey Open-File
Report 84-523, Scale 1:2,500,000

Silberling, N.J., Jones, D.L., Monger, J.W.H., Coney, P.J., Berg, H.C.,
and Plafker, George, 1994, Lithotectonic terrane map of Alaska and
adjacent parts of Canada, *in* Plafker, George, and Berg, H.C., eds.,
The Geology of Alaska: Geological Society of America, The Geology of
North America, Boulder, Colorado, plate 3, scale 1:2,500,000.

Silberman, M.L., Moll, E.J., Patton, W.W., Jr., Chapman, R.M., and
Conner, C.L., 1979, PreCambrian age of metamorphic rocks from the Ruby
province, Medfra and Ruby quadrangles\--preliminary evidence from
radiometric age data, *in* Johnson, K.M., and Williams, J.R., eds., The
United States Geological Survey in Alaska: Accomplishments during 1978:
U.S. Geological Survey Circular 804-B, p. B64, B66-B68.

Solie, D.N., Gilbert, W.G., Harris, E.E., Kline, J.T., Liss, S.A., and
Robinson, M.S., 1991, Preliminary geologic map of Tyonek D-6 and eastern
Tyonek D-7 quadrangles, Alaska: Alaska Division of Geological and
Geophysical Surveys Public-data File 91-10, scale 1:63,360, 15 p., not
paginated.

Smith, T.E., 1981, Geology of the Clearwater Mountains, south-central
Alaska: Alaska Division of Geological and Geophysical Surveys Geologic
Report 60, 1 sheet, scale 1:63,360, 73 p.

Smith, T.E., Albanese, M.D., and Kline, G.L., 1984, Geologic map of the
Healy A-2 quadrangle, Alaska: Alaska Division of Geological and
Geophysical Surveys Professional Report 95, 1 sheet, scale 1:63,360.

Smith, T.E., Robinson, M.S., Weber, F.R., Waythomas, C.W., and
Reifenstuhl, R.R., 1994, Geologic map of the Upper Chena River area,
eastern interior Alaska: Alaska Division of Geological and Geophysical
Surveys Professional Report 115, scale 1:63,360, 19 p.

Spurr, J.E., 1900, A reconnaissance in southwestern Alaska in 1898: U.S.
Geological Survey 20th Annual Report, Part 7, p. 31-264.

Steiger, R.H., and Jager, E., 1977, Subcommission on Geochronology:
Convention on the use of decay constants in geo- and cosmochronology:
Earth and Planetary Science Letters, v. 36, p. 359-362.

Turner, D.L., and Smith, T.E., 1974, Geochronology and generalized
geology of the central Alaska Range, Clearwater Mountains, and northern
Talkeetna Mountains: Alaska Division of Geological and Geophysical
Surveys Open-File Report AOF-72, 11 p., 1 sheet.

Wahrhaftig, Clyde, 1968, Schists of the central Alaska Range: U.S.
Geological Survey Bulletin 1254- E, p. E1-E22.

Weber, F.R., Foster, H.L., Keith, T.E.C., and Dusel-Bacon, Cynthia,
1978, Preliminary geologic map of the Big Delta quadrangle, Alaska: U.S.
Geological Survey Open-File Report 78-529A, scale 1:250,000.

Weber, F.R., Wheeler, K.L., Rinehart, C.D., Chapman, R.M., and Blodgett,
R.B., 1992, Geologic map of the Livengood quadrangle, Alaska: U.S.
Geological Survey Open-File Report 92-562, scale 1:250,000, 19 p.

Wilson, F.H., Smith, J.G., and Shew, Nora, 1985, Review of radiometric
data from the Yukon Crystalline terrane, Alaska and Yukon Territory:
Canadian Journal of Earth Sciences, v. 22, no. 4, p. 525-537.

Wilson, F.H., Weber, F.R., and Angeloni, Linda, 1984, Late Cretaceous
thermal overprint and metamorphism, southeast Circle quadrangle, Alaska
\[abs.\]: Geological society of America Abstracts with Programs, v. 16,
no. 5, p. 340.

Wiltse, M.A., Reger, R.D., Newberry, R.J., Pessel, G.H., Pinney, D.S.,
Robinson, M.S., and Solie, D.N., 1995, Geologic map of the Circle Mining
District, Alaska: Alaska Division of Geological and Geophysical Surveys
Report of Investigations 95-2a, scale 1:63,360.

Winkler, G.R., Silberman, M.L., Grantz, Arthur, Miller, R.J., and
MacKevett, E.M., Jr., 1980, Geologic map and summary geochronology of
the Valdez quadrangle, southern Alaska: U.S. Geological Survey Open-File
Report 80-892-A, scale 1:250,000, 2 sheets.

Winkler, G.R., compiler, 1992, Geologic map and summary geochronology of
the Anchorage 1° x 3° quadrangle, southern Alaska: U.S. Geological
Survey Miscellaneous Investigations Series Map I-2283, scale 1:250,000.

List of Map Sources

Anchorage:

AN1: Winkler, G.R., compiler, 1992, Geologic map and summary
geochronology of the Anchorage 1° x 3° quadrangle, southern Alaska: U.S.
Geological Survey Miscellaneous Investigations Series Map I-2283,, scale
1:250,000.

Big Delta:

BD1: Weber, F.R., Foster, H.L., Keith, T.E.C., and Dusel-Bacon, Cynthia,
1978, Preliminary geologic map of the Big Delta quadrangle, Alaska: U.S.
Geological Survey Open-File Report 78-529A, scale 1:250,000.

BDCI1: Smith, T.E., Robinson, M.S., Weber, F.R., Waythomas, C.W., and
Reifenstuhl, R.R., 1994, Geologic map of the Upper Chena River area,
eastern interior Alaska: Alaska Division of Geological and Geophysical
Surveys Professional Report 115, scale 1:63,360, 19 p.

Circle:

CI1: Foster, H.L., Laird, Jo, Keith, T.E.C., Cushing, G.W., and Menzie,
D.W., 1983, Preliminary geologic map of the Circle quadrangle, Alaska:
U.S. Geological Survey Open-File Report, 83-170-A, scale 1:250,000.

CI2: Wiltse, M.A., Reger, R.D., Newberry, R.J., Pessel, G.H., Pinney,
D.S., Robinson, M.S., and Solie, D.N., 1995, Geologic map of the Circle
Mining District, Alaska: Alaska Division of Geological and Geophysical
Surveys Report of Investigations 95-2a, scale 1:63,360.

CI3: Weber, F.R, Unpublished mapping, 1997, scale 1:250,000.

BDCI1: Smith, T.E., Robinson, M.S., Weber, F.R., Waythomas, C.W., and
Reifenstuhl, R.R., 1994, Geologic map of the Upper Chena River area,
eastern interior Alaska: Alaska Division of Geological and Geophysical
Surveys Professional Report 115, scale 1:63,360, 19 p.

FMD1: Robinson, M.S., Smith, T.E., and Metz, P.A., 1990, Bedrock geology
of the Fairbanks Mining District: Alaska Division of Geological and
Geophysical Surveys Professional Report 106, scale 1:63,360.

FMD1: Newberry, R.J., Bundtzen, T.K, Clautice, K.H., Combellick, R.A.,
Douglas, T., Laird, G.M., Liss, S.A., Pinney, D.S., Reifenstuhl, R.R.,
and Solie, D.N., 1996, Preliminary geologic map of the Fairbanks Mining
District, Alaska: Alaska Division of Geological and Geophysical Surveys
Public Data File 96-16, scale 1:63,360.

Fairbanks:

FB1: Pewe, T.L., Wahrhaftig, C., and Weber, F., 1966, Geologic map of
the Fairbanks quadrangle, Alaska: U.S. Geological Survey, Miscellaneous
Investigations I-455, scale 1:250,000, 5 p.

FMD1: Newberry, R.J., Bundtzen, T.K, Clautice, K.H., Combellick, R.A.,
Douglas, T., Laird, G.M., Liss, S.A., Pinney, D.S., Reifenstuhl, R.R.,
and Solie, D.N., 1996, Preliminary geologic map of the Fairbanks Mining
District, Alaska: Alaska Division of Geological and Geophysical Surveys
Public Data File 96-16, scale 1:63,360.

FMD1: Robinson, M.S., Smith, T.E., and Metz, P.A., 1990, Bedrock geology
of the Fairbanks Mining District: Alaska Division of Geological and
Geophysical Surveys Professional Report 106, scale 1:63,360.

Gulkana:

GU1: Nokleberg, W.J., Richter, D.H., Ferrians, O.J., Lange, I.M.,
Campbell, D.L., Aleinikoff, J.N., Smith, T.E., and Koch, R.D., in press,
Introduction, previous studies, acknowledgements, detailed description
of map units, geologic and tectonic summary, and references cited for
preliminary geologic map of the Gulkana quadrangle, eastern Alaska Range
and northern Copper River basin, Alaska: U.S. Geological Survey
Open-File Report, in press \[CAD coverage 1997\]

Healy:

HE1: Csejtey, Bela, Jr., Mullen, M.W., Cox, D.P., and Stricker, G.D.,
1992, Geology and geochronology of the Healy quadrangle, south-central
Alaska: U.S. Geological Survey Miscellaneous Investigations Series Map
I-1961, scale 1:250,000, 63 p.

HE2: Smith, T.E., 1981, Geology of the Clearwater Mountains,
south-central Alaska: Alaska Division of Geological and Geophysical
Surveys Geologic Report 60, 1 sheet, scale 1:63,360, 73 p.

HE3: Smith, T.E., Albanese, M.D., and Kline, G.L., 1984, Geologic map of
the Healy A-2 quadrangle, Alaska: Alaska Division of Geological and
Geophysical Surveys Professional Report 95, 1 sheet, scale 1:63,360.

Iditarod:

ID1: Miller, M.L, and Bundtzen, T.K., 1994, Generalized geologic map of
the Iditarod quadrangle, Alaska, showing potassium-argon, major-oxide,
trace-element, fossil, paleocurrent, and archaeological sample
localities: U.S. Geological Survey Miscellaneous Field Studies Map
MF-2219A, scale 1:250,000, 48 p. (With revisions from unpublished data,
M.L. Miller and T.K. Bundtzen, 1997)

Kantishna River:

KH1: Chapman, R.M., Yeend, W.E., Patton, W.W., Jr., 1975, Preliminary
reconnaissance geologic map of the western half of Kantishna River
quadrangle, Alaska: U.S. Geological Survey Open File Report 75-351,
scale 1:250,000.

KH2: Chapman, R.M., and Yeend, Warren, 1981, Geologic reconnaissance of
the east half of Kantishna River quadrangle and adjacent areas, in
Albert, N.R.D., and Hudson, Travis, ed., The United States Geological
Survey in Alaska: Accomplishments during 1979: U.S. Geological Survey
Circular 823-B, p. B30-B32.

KH3: Weber, F.R, Unpublished mapping, 1997, scale 1:250,000.

Kateel River:

KT1: Patton, W.W., Jr., 1966, Regional geology of the Kateel River
quadrangle, Alaska: U.S. Geological Survey Miscellaneous Investigations
Map I-437, 1 sheet, 1:250,000. (With revisions from unpublished data,
W.W. Patton, Jr., 1997)

Lime Hills:

LH1: Gamble, B.M., and Reed, B.L., 1996, Preliminary geologic map of the
eastern half of the Lime Hills quadrangle, Alaska: unpublished U.S.
Geological Survey map compilation, scale 1:250,000.

LH2: Bundtzen, T.K., West half of the Lime Hills quadrangle, Alaska:
Unpublished mapping, 1997.

LH2: Reed, B.L., and Gamble, B.M., 1988, Preliminary geologic map of the
Lime Hills quadrangle, Alaska, *in* Gamble, B.M., Allen, M.S., McCammon,
R.B., Root, D.H., Scott, W.A., Griscom, Andrew, Krohn, M.D., Ehmann,
W.J., and Southworth, S.C., Lime Hills quadrangle, Alaska \-- An AMRAP
planning document: U.S. Geological Survey Administrative report, 167 p.,
22 plates. (*Used only the west half of this map, see above.*)

Livengood:

LG1: Weber, F.R., Wheeler, K.L., Rinehart, C.D., Chapman, R.M., and
Blodgett, R.B., 1992, Geologic map of the Livengood quadrangle, Alaska:
U.S. Geological Survey Open-File Report 92-562, 19 p., scale 1:250,000.
(With revisions from unpublished data, F.R. Weber, 1997)

FMD1: Newberry, R.J., Bundtzen, T.K, Clautice, K.H., Combellick, R.A.,
Douglas, T., Laird, G.M., Liss, S.A., Pinney, D.S., Reifenstuhl, R.R.,
and Solie, D.N., 1996, Preliminary geologic map of the Fairbanks Mining
District, Alaska: Alaska Division of Geological and Geophysical Surveys
Public Data File 96-16, scale 1:63,360.

FMD1: Robinson, M.S., Smith, T.E., and Metz, P.A., 1990, Bedrock geology
of the Fairbanks Mining District: Alaska Division of Geological and
Geophysical Surveys Professional Report 106, scale 1:63,360.

McGrath:

MG1: Bundtzen, T.K., Harris, E.E., and Gilbert, W.G., 1997, Geologic map
of the eastern half of the McGrath quadrangle, Alaska: Alaska Division
of Geological and Geophysical Surveys Report of Investigations 97-14a,
scale 1:125,000, 34 p.

MG2: Bundtzen, T.K., 1997, Unpublished draft compilation of the western
half of the McGrath quadrangle, Alaska, Cited references include:\
\
Babcock, L.E., Blodgett, R.B., and St. John, J., 1994, New Late(?)
Proterozoic age formations in the vicinity of Lone Mountain, McGrath
quadrangle, west-central Alaska: U.S. Geological Survey Bulletin 2107,
p. 143-156.\
\
Blodgett, R.B. and Gilbert, W.G., The Cheeneetuk Limestone \-- a new
Early(?) to Middle Devonian Formation in the McGrath A-4 and A-5
quadrangles, Alaska: Alaska Division of Geological and Geophysical
Surveys Professional Report 85, 6 p., 1 sheet, scale 1:63,360.\
\
Bundtzen, T.K., 1986, Geology and prospect examination of the Vinasale
Mt.-Alder Creek area, McGrath C-6 quadrangle, Alaska: Alaska Division of
Geological and Geophysical Surveys Public Data 86-15, 10 p., 1 figure,
scale 1:63,360.\
\
Bundtzen, T.K., and Laird, G.M., 1983, Geologic map of the McGrath D-6
quadrangle, Alaska: Alaska Division of Geological and Geophysical
Surveys Geologic Report 79, scale 1:63,360.\
\
Dutro, J.T., Jr., and Patton, W.W., Jr., 1982, New Paleozoic formations
in the northern Kuskokwim Mountains, west-central Alaska: U.S.
Geological Survey Bulletin 1529-H, p. H13-H22.

Medfra:

MD1: Patton, W.W., Jr., Moll, E.J., Dutro, J.T., Jr., Silberman, M.L.,
and Chapman, R.M., 1980, Preliminary geologic map of the Medfra
quadrangle, Alaska: U.S. Geological Survey Open-File Report 80-811A, 1
sheet, scale 1:250,000.

OPMD1: Bundtzen, T.K., Pinney, D.S., and Laird, G.M., 1997b, Preliminary
geologic map and data table from the Ophir C-1 and western Medfra C-6
quadrangles, Alaska: Alaska Division Geological and Geophysical Surveys
Public Data File 97-46, scale 1:63,360, 10 p.

Mount Hayes:

MH1: Nokleberg, W.J., Aleinikoff, J.N., Lange, I.M., Silva, S.R.,
Miyaoka, R.T., Schwab, C.E., and Zehner, R.E., with contribution for
selected areas from Bond, G.C., Richter, D.H., Smith, T.E., and Stout,
J.H., 1992, Preliminary geologic map of the Mount Hayes quadrangle,
eastern Alaska Range, Alaska: U.S. Geological Survey Open File Report
92-594, scale 1:250,000.

Mount McKinley:

MM1: Csejtey, Bela, Jr., 1993, Unpublished draft compilation of the
Mount McKinley quadrangle, Alaska

MM1: Gilbert, W.G., 1979, A geologic guide to Mount McKinley National
Park: Alaska Natural History Association, in cooperation with the
National Park Service, U.S. Dept. of the Interior, 52 p., 1 plate, scale
1:250,000.

MM1: Reed, J.C., Jr., 1961, Geology of the Mount McKinley quadrangle,
Alaska: U.S. Geological Survey Bulletin 1108-A, 36 p., 1 map, scale
1:250,000.

Melozitna:

MZ1: Patton, W.W., Miller, T.P., Chapman, R.M., and Yeend, Warren, 1978,
Geologic map of the Melozitna quadrangle, Alaska: U.S. Geological Survey
Miscellaneous Geologic Investigations Map I-1071, scale 1:250,000.

MZ2: Roeske, S.M., Dusel-Bacon , C., Aleinikoff, J.N., Snee, L.W., and
Lanphere, M.A., 1995, Metamorphic and structural history of continental
crust at a Mesozoic collisional margin, the Ruby terrane, central
Alaska: Journal of Metamorphic Geology v. 13, p. 25-40.

Nulato:

NL1: Patton, W.W., Jr., 1994, Unpublished draft compilation of the
Nulato quadrangle, Alaska.

Ophir:

OP1: Chapman, R. M., Patton, W. W. Jr., and Moll, E. J., 1985,
Reconnaissance geologic map of the Ophir quadrangle, Alaska: U.S.
Geological Survey Open-File Report 85-203, 1 sheet, scale 1:250,000.

OP1: Chapman, R.M., Patton, W.W. Jr., and Moll, E.J., 1982, Preliminary
summary of geology in eastern part of Ophir quadrangle, in Coonrad,
W.L., ed., The United States Geological Survey in Alaska:
Accomplishments during 1980: U.S. Geological Survey Circular 844, p.
70-73.

OPMD1: Bundtzen, T.K., Pinney, D.S., and Laird, G.M., 1997b, Preliminary
geologic map and data table from the Ophir C-1 and western Medfra C-6
quadrangles, Alaska: Alaska Division Geological and Geophysical Surveys
Public Data File 97-46, scale 1:63,360, 10 p.

Ruby:

RB1: Cass, J.T., 1959, Reconnaissance geologic map of the Ruby
quadrangle, Alaska: U.S. Geological Survey Miscellaneous Investigation
Map I-289, 1 sheet, scale 1:250:000 \[Geologic linework transcribed by
David Dempsey, 1996, to fit modern topographic base\].

RB2: Chapman, R.M., and Patton, W.W., Jr., 1978, Preliminary summary of
the geology in the northwest part of the Ruby quadrangle, *in* Johnson,
K.M., ed., The United States Geological Survey in Alaska:
Accomplishments during 1977: U.S. Geological Survey Circular 772-B, p.
B39-B41.

RB3: Chapman, R.M., and Patton, W.W., Jr., 1979, Two upper Paleozoic
rock units identified in southwestern part of the Ruby quadrangle, *in*
Johnson, K.M., and Williams, J.R., eds., The United States Geological
Survey in Alaska: Accomplishments during 1978: U.S. Geological Survey
Circular 804-B, p. B59-B61.

RB4: Puchner, C.C., 1984, Geologic map of the Ruby/Poorman area:
Unpublished Anaconda Mining Company Report, scale 1:250,000, written
commun., 1997.

RB5: Dusel-Bacon, Cynthia, Brosge, W.P., Till, A.B., Doyle, E.O.,
Mayfield, C.F., Reiser, H.N., and Miller, T.P., 1989, Distribution,
facies, ages, and proposed tectonic associations of regionally
metamorphosed rocks in northern Alaska: U.S. Geological Survey
Professional Paper 1497-A, 44 p., 2 plates., 1:1,000,000-scale.

Sleetmute:

SM1: Miller, M.L., Belkin, H.E., Blodgett, R.B., Bundtzen, T.K., Cady,
J.W., Goldfarb, R.J., Gray, J.E., McGimsey, R.G., and Simpson, S.L.,
1989, Pre-field study and mineral resource assessment of the Sleetmute
quadrangle, southwestern Alaska: U.S. Geological Survey Open-File Report
89-363, 115 p., 1 map, scale 1:250,000.

SM2: Bundtzen, T.K., Laird, G.M., Harris, E.E., Kline, J.T., and Miller,
M.L., 1993, Geologic map of the Sleetmute C-7, D-7, C-8, and D-8
Quadrangles, Horn Mountains area, southwest Alaska: Alaska Division of
Geological and Geophysical Surveys Public-Data File 93-47, 15 p., 2
sheets, scale 1:63,360.

Talkeetna:

TL1: Reed, B.L., and Nelson, S.W., 1980, Geologic map of the Talkeetna
quadrangle, Alaska: U.S. Geological Survey, Miscellaneous Investigation
Series Map I-1174, 15 pages, 1 plate, scale 1:250,000.

Talkeetna Mountains:

TK1: Csejtey, Bela, Jr., Nelson, W.H., Jones, D.L., Silberling, N.J.,
Dean, R.M., Morris, M.S., Lanphere, M.A., Smith, J.G., and Silberman,
M.L., 1978, Reconnaissance geologic map and geochronology, Talkeetna
Mountains quadrangle, northern part of Anchorage quadrangle, and
southwest corner Healy quadrangle, Alaska: U.S. Geological Survey
Open-file Report 78-558A, scale 1:250,000, 60 p.

TK2: Kline, J.T., Bundtzen, T.K., and Smith, T.E., 1990, Preliminary
bedrock geologic map of the Talkeetna Mountains D-2 quadrangle, Alaska:
Alaska Division Geological and Geophysical Surveys Public Data File
90-24, scale 1:63,360, not paginated.

Tanana:

TN1: Dover, J.H., 1997, Unpublished draft compilation of the Tanana
quadrangle, Alaska, scale 1:250,000.

TN1: Chapman, R.M., Yeend, Warren, Brosge, W.P., and Reiser, H.N., 1982,
Reconnaissance geologic map of the Tanana quadrangle, Alaska: U.S.
Geological Survey Open-File Report 82-734, scale 1:250,000, 18 p.

TN2: Reifenstuhl, R.R., Dover, J.H., Pinney, D.S., Newberry, R.J.,
Clautice, K.H., Liss, S.A., Blodgett, R.B., Bundtzen, T.K., and Weber,
F.R., 1997, Geologic map of the Tanana B-1 quadrangle, central Alaska:
Alaska Department of Geological and Geophysical Surveys Report of
Investigations 97-15a, scale 1:63,360, 17 p.

TN3: Reifenstuhl, R.R., Dover, J.H., Newberry, R.J., Clautice, K.H.,
Liss, S.A., Blodgett, R.B., and Weber, F.R., 1998, Geologic map of the
Tanana A-1 and A-2, central Alaska: Alaska Department of Geological and
Geophysical Surveys Public Data File 98-37a, scale 1:63,360.

Tyonek:

TY1: Haeussler, P.J., 1997, Unpublished draft compilation of the Tyonek
quadrangle, Alaska, scale 1:250,000.

TY1: Magoon, L.B. Adkison, W.L., and Egbert, R.M, 1976, Map showing
geology, wildcat wells, Tertiary plant localities, K/Ar age dates, and
petroleum operations, Cook Inlet area, Alaska: U.S. Geological Survey
Miscellaneous Investigations Series Map I-1019, scale 1:250,000, 3
sheets.

TY2: Reed, B.L, and Elliott, R.L., 1970, Reconnaissance geologic map,
analyses of bedrock and stream sediment samples, and an aeromagnetic map
of parts of the southern Alaska Range: U.S. Geological Survey Open File
Report 70-271, scale 1:63,360, 24 p.

TY3: Solie, D.N., Gilbert, W.G., Harris, E.E., Kline, J.T., Liss, S.A.,
and Robinson, M.S., 1991, Preliminary geologic map of Tyonek D-6 and
eastern Tyonek D-7 quadrangles, Alaska: Alaska Division of Geological
and Geophysical Surveys Public-data File 91-10, scale 1:63,360, 15 p.,
not paginated.

Valdez:

VA1: Winkler, G.R., Silberman, M.L., Grantz, Arthur, Miller, R.J., and
MacKevett, E.M., Jr., 1980, Geologic map and summary geochronology of
the Valdez quadrangle, southern Alaska: U.S. Geological Survey Open-File
Report 80-892-A, scale 1:250,000, 2 sheets. (With revisions from
unpublished data, G.R. Winkler, 1997)

VA2: Plafker, George, Lull, J.S., Nokleberg, W.J., Pessel, G.A.,
Wallace, W.K., and Winkler, G.R., 1992, Geologic map of the Valdez A-4,
B-3, B-4, C-3, C-4, D-4 quadrangles, northern Chugach Mountains and
southern Copper River basin, Alaska: U.S. Geological Survey
Miscellaneous Investigations Series Map I-2164.

Index of map units

bu Bedrock of unknown type or age 3

CZds Unnamed dolostone, sandstone, siltstone 35

CZw Wickersham grit, undivided 43

CZwa Argillaceous upper unit 44

CZwl Wickersham limestone 44

Dcb Cascaden Ridge, Beaver Bend, and\
correlative rocks 36

DCd Dillinger sequence, undivided 33

Dm Marble 43

Dml Older limestone 29

Dps Phyllite, slate, siliceous siltstone, and\
argillite 36

Dq Quail unit 36

Ds Schwatka limestone unit 36

Dsb Serpentinite, basalt, chert and gabbro 25

DSbr Barren Ridge Limestone and correlative\
units 34

Dsc Shale and chert 29

DSl Limestone 37

DSlc Lost Creek unit 37

DSmdl Unnamed limestone 30

DSt Tolovana Limestone 37

Dsv Volcanic part of Schwatka unit 36

DSwc Whirlwind Creek Formation and\
unnamed correlative units 34

Dtr Troublesome unit and possibly\
correlative rocks 36

Dy Yanert Fork sequence and correlative\
rocks 38

Dys Fine-grained schistose sedimentary rocks 38

Dyv Fine-grained schistose volcanic rocks 39

DZn Shallow-marine carbonate units of Holitna\
basin area, undivided 34

Jaum Ultramafic rocks (Jurassic?) 25

Jc Chinitna Formation 20

JCmd Mystic and Dillinger stratigraphic\
sequences, undivided 30

Jct Chinitna Formation, Tuxedni Group,\
and coeval sedimentary rocks 19

JDm Mystic stratigraphic sequence, undivided 29

Ji Alaska-Aleutian Range and Chitina\
Valley batholiths, undifferentiated 21

Jium Ultramafic and mafic\
rocks, undivided 27

Jkt Kotsina Conglomerate 20

JMab Basalt and chert 26

JMtru Greenstone, chert, and ultramafic\
rocks, undivided 26

JMtu Mafic, ultramafic, and sedimentary\
rocks, undivided 27

Jmu Mafic and ultramafic rocks 20

Jn Naknek Formation 19

JPaur Uranatina metaplutonic complex 21

Jps Pelitic schist 21

JPsu Ultramafic rocks 25

JPzk Kakhonak Complex 31

JPzsgs Greenstone and chert 25

JPztm Mafic and ultramafic rocks, undivided 27

Jsch Greenschist and blueschist 21

Jtr Trondhjemite 21

JT[r]{.smallcaps}ct Crystal tuff, argillite, chert, graywacke,\
and limestone 24

JT[r]{.smallcaps}lm Limestone and marble 22

JT[r]{.smallcaps}mc McCarthy Formation 22

JT[r]{.smallcaps}su Red and brown sedimentary rocks and\
basalt 24

JT[r]{.smallcaps}ta Cherty tuff, crystal and lithic tuffs,\
and volcanic breccia 27

JT[r]{.smallcaps}tk Talkeetna Formation 22

JT[r]{.smallcaps}tmu Mafic and ultramafic rocks 26

JT[r]{.smallcaps}tv Tatina River Volcanic and equivalent\
units 29

Jtu Ultramafic rocks, undivided 27

Jtx Tuxedni Group 20

Kb Berg Creek Formation 14

Kcg Igneous pebble-cobble conglomerate 13

Kcs Cantwell Formation, sedimentary\
rocks subunit 11

Kg Granitic rocks 16

Kgw Graywacke sandstone and mudstone 14

KJcg Conglomerate, sandstone, siltstone,\
shale, and volcanic rocks 18

KJf Kahiltna flysch sequence 17

KJfk Flysch sequence 18

KJfm Metasedimentary rocks 18

KJfn Flysch sequence 18

KJg Granitic rocks 19

KJhc Haley Creek metaplutonic and\
metasedimentary rocks 19

KJs Argillite, chert, sandstone, and limestone 17

KJvr Vrain unit 19

KJw Wolverine quartzite 17

KJwc Wilber Creek flysch and Wolverine\
quartzite, undivided 17

Kk Kuskokwim Group, deep marine rocks 12

Kkn Kuskokwim Group, non-marine and\
shallow-marine rocks 12

Km Matanuska Formation 11

Kmar Melanges of the Alaska Range 15

Kme Melozitna sequence 12

Kmm Marine mudstone and sandstone 13

Kms Minto unit 11

Kmum Mafic and ultramafic rocks 16

Knb Norton Bay sequence 13

Knl Nelchina Limestone 14

Kqc Quartz-pebble conglomerate 13

Kshn Nonmarine shale, siltstone, and\
sandstone 13

Ksm Quartz-carbonate sandstone and\
pebbly mudstone 14

Kss Nonmarine sandstone, quartz\
conglomerate, shale, and siltstone 13

Ksse Marine sandstone and siltstone 13

Ktg Volcaniclastic rocks 16

KT[r]{.smallcaps}g Gemuk Group 10

KT[r]{.smallcaps}m McHugh Complex 15

Ktt Leucotonalite and trondhjemite 16

Kve Andesite and related rocks 16

Kvgm Volcanic graywacke and mudstone 14

Kvl Volcanic rocks 16

Kvm Volcanic graywacke and conglomerate 13

Kvs Metasedimentary rocks of the Valdez\
Group 17

Kvv Metavolcanic rocks of Valdez Group 17

Kwcf Wilber Creek flysch 14

MDl Fine-grained limestone 28

MDrao Augen orthogneiss 43

MDt Totatlanika Schist 40

MDtm Mylonitic Totatlanika Schist 40

MDyao Augen orthogneiss 40

Mgq Globe quartzite 35

mlu Ultramafic and associated rocks 15

Mzi Intrusive rocks 10

Mzpca Phyllite, pelitic schist, calc-schist, and\
amphibolite of the MacLaren\
metamorphic belt 11

MzPzi Intrusive and volcanic rocks, undivided 31

Mzsa Schist and amphibolite 11

Mzum Ultramafic and associated rocks 10

MzZum Ultramafic and mafic rocks, undivided 31

Oc Chert 38

Ocl Limestone 38

Ofc Fossil Creek Volcanics 38

Ont Novi Mountain and Telsitna Formations,\
and unnamed correlative rocks 35

Pagb Gabbro and orthogneiss 32

Pat Tetelna Volcanics 32

PDms Sedimentary rocks 35

PDsc Sheep Creek Formation and correlative\
siliciclastic units 29

Pe Eagle Creek Formation 32

Pig Graywacke 28

Pmi Shallow stocks, dikes, and sills 32

PMl Younger limestone 29

PMpc Phyllite and chert 38

PPad Diorite complex 32

PPagi Ahtell pluton 32

PPasc Station Creek and Slana Spur\
Formations, and equivalent rocks 32

PPaskm Marble 33

PPast Strelna metamorphic complex 33

Ps Argillite, siltstone, sandstone, and\
minor conglomerate 35

Pze Eclogite-bearing schist 40

Pzk Keevy Peak Formation 40

Pzkcp Calcareous and phyllitic rocks 41

Pzlc Limestone and chert 35

Pzlsl Schist, phyllite, limestone, and\
greenstone 39

Pzrm Marble 42

Pzrmi Metamorphosed mafic igneous rocks 42

Pzsc Spruce Creek sequence and correlative\
rocks 39

Pzvs Volcanic and sedimentary rocks 38

Pzydm Dolostone and marble 39

PzZaqs Pelitic and quartzose schist of the Alaska\
Range 41

PzZrpg Quartzofeldspathic paragneiss and\
quartzite 43

PzZrqs Pelitic and quartzitic schist 43

PzZyg Gneiss 42

PzZygs Gneiss, schist, and quartzite 42

PzZym Mafic schist 41

PzZyqs Quartz- and pelitic schist of the Yukon-\
Tanana Upland 41

PzZysa Schist and amphibolite 42

Qs Surficial deposits, undifferentiated 3

QTi Intrusive rocks, undivided 3

QTv Volcanic rocks, undivided 3

Qv Volcanic rocks, undivided 3

SCpl Post River Sandstone, Lyman Hills\
Formation, and correlative units 34

Spf Paradise Fork Formation and unnamed\
correlative rocks 34

Stc Terra Cotta Mountains Sandstone and\
correlative units 34

SZa Amy Creek unit 37

Tar Arkose Ridge Formation 5

Tb Basalt 6

Tba Basaltic andesite 6

Tcb Coal-bearing rocks 4

Tch Chickaloon Formation 5

Tcv Volcanic rocks of the Cantwell Formation 7

Td Felsic intrusive rocks 7

TDg Gabbro 9

Tegr Granite and granodiorite 7

Tfv Fluviatile sedimentary rocks and\
subordinate volcanic rocks 5

Tgl Gabbro 8

Thd Hornblende dacite 6

Thf Hypabyssal felsic and intermediate\
intrusive rocks 6

Thgd Granodiorite and other intermediate\
plutonic rocks 8

Thm Hypabyssal mafic intrusive rocks 6

Tiv Granitic and volcanic rocks, undivided 7

Tk Kenai Group, undivided 3

Tkb Beluga Formation 4

TKc Melange or cataclastite of the Orca Group 9

TKcg Conglomerate, sandstone, and lignite 8

TKd Dikes and subvolcanic rocks of\
intermediate composition 8

TKg Granitic rocks 9

TKgb Gabbro and leucogabbro 9

TKgd Granodiorite, tonalite, and monzonite\
dikes, and stocks 9

TKgg Gneissose granitic rocks 9

TKgp Hypabyssal granite porphyry dikes and\
rhyolitic sills, and plugs 8

TKi Intrusive rocks, undivided 9

TKiv Mafic to intermediate volcano-plutonic\
complexes 9

TKl Lamprophyre, alkali gabbro, and\
alkali diorite 9

TKqd Quartz diorite and diorite dikes and stocks 9

TKv Flows, tuff, and breccia, undivided 8

TKvi Andesite and related rocks 9

TKvr Rhyolite and related rocks 8

Tn Nenana Gravel 4

Toc Conglomerate of the Orca Group 5

Toegr Granitic rocks 7

Toem Granodiorite to tonalite 7

Togr Granite 7

Tos Sedimentary rocks of the Orca Group 5

Tov Volcanic rocks of the Orca Group,\
undivided 5

Tovs Orca Group, undivided 5

Tpgr Granitic rocks 8

TPza Amphibolite facies metamorphic rocks 10

T[r]{.smallcaps}c Carbonatite 23

T[r]{.smallcaps}cg Conglomerate and volcanic sandstone 23

T[r]{.smallcaps}cs Calcareous sedimentary rocks 22

T[r]{.smallcaps}Dv Volcanic and sedimentary rocks 25

T[r]{.smallcaps}gb Gabbro, diabase, and metagabbro 24

T[r]{.smallcaps}lb Limestone and basalt sequence 24

T[r]{.smallcaps}ls Chitistone and Nizina Limestones,\
undivided 22

T[r]{.smallcaps}Mica Chert, argillite, and volcaniclastic rocks 28

T[r]{.smallcaps}Mis Sandstone, grit, and argillite 28

T[r]{.smallcaps}Mtqp Quartzite and phyllite 27

T[r]{.smallcaps}Mts Sedimentary rocks 26

T[r]{.smallcaps}Mtsu Sedimentary rocks, undivided 27

T[r]{.smallcaps}n Nikolai Greenstone and related rocks 23

T[r]{.smallcaps}nm Metavolcanic and associated\
metasedimentary rocks 24

T[r]{.smallcaps}Pas Flysch-like sedimentary rocks 30

T[r]{.smallcaps}ps Phosphatic shale and limestone 23

T[r]{.smallcaps}Ps Sedimentary rocks, undivided 30

T[r]{.smallcaps}r Red beds 25

Trs Rhyolitic volcanic and sedimentary rocks 5

T[r]{.smallcaps}sc Black shale and chert 23

T[r]{.smallcaps}Sl Limestone blocks 15

T[r]{.smallcaps}sl Spiculite and sandy limestone 22

Tsf Sterling Formation 4

Tsu Sedimentary rocks, undivided 3

Tts Tsadaka Formation 4

Ttw Tsadaka, West Foreland, and Wishbone Formations, undivided 4

Tty Tyonek Formation 4

Tvb Andesite and basalt 6

Tvr Crystal and crystal-lithic ash-flow tuff 6

Tvs Volcanic and sedimentary rocks,\
undivided 4

Tvu Volcanic rocks, undivided 5

Tw Wishbone Formation 4

Twf West Foreland Formation 4

Xi Idono metamorphic complex 45

Ynqd Meta-quartz diorite 45

Zwg Gritty lower unit 44

ZYnc Calc-schist 44

ZYnm Metamorphic basement rocks of the\
Nixon Fork sequence, undivided 44

ZYns Pelitic schist 44

ZYnv Metavolcanic rocks 45

Appendix A. Exploratory drillholes in Central (Interior) Alaska

The data in the following table on exploratory drillholes in the map
area was provided by the Alaska Division of Oil and Gas (DOG). A map
showing the distribution of these wells in the map area is shown on
sheet 3 as figures 5a and 5b. This data set has been abstracted from a
database of drill holes in Alaska maintained by DOG. Explanation for
coded entries in columns of the table is as below:

Column Entries

Map Number Shown on figures 5a and 5b , sheet 3

API number \--

Well name \--

Operator name \--

Status P&A, plugged and abandoned;\
P&A-G, plugged and abandoned, gas show(s);\
P&A-O, plugged and abandoned, oil show(s);\
P&A-OC, plugged and abandoned, \"significant\" oil show;\
P&A-OG, plugged and abandoned, oil and gas show(s);\
GAS, gas producer;\
SUSP-O, suspended, oil show(s);\
SUSP-G, suspended, gas show(s)

Completion date \--

Permit number \--

Area KOYK - Koyukuk;\
MTAN - Middle Tanana;\
COPR - Copper River;\
SUSIT - Susitna;\
CI - Cook Inlet

Latitude At surface, decimal degress, N

Longitude At surface, decimal degrees, W

Township Number and direction, at surface

Range Number and direction, at surface

Section Section number

Meridian At surface

Bottonhole latitude Decimal degrees

Bottomhole longitude Decimal degrees

Bottomhole township Number and direction

Bottomhole range Number and direction

Bottomhole section Section number

Total depth Feet