**INTRODUCTION**

This pamphlet contains an introduction, tectonic definitions,
acknowledgments, descriptions of post-accretion stratified rocks, and
descriptions for tectonostratigraphic terranes, and references for the
companion tectono-stratigraphic terrane and overlap assemblage map of
Alaska. The companion map describes and depicts the
tectono-stratigraphic terranes and major overlap assemblages, except for
the Aleutian Islands. In Alaska the major overlap assemblages consist
mainly of upper Mesozoic sedimentary rocks, and Upper Cretaceous and
Cenozoic sedimentary and volcanic and plutonic rocks of Alaska that were
deposited on, or intruded into adjacent terranes after tectonic
juxtaposition or accretion.

A tectonostratigraphic terrane is define as a fault-bounded geologic
entity or fragment that is characterized by a distinctive geologic
history that differs markedly from that of neighboring terranes (Jones
and others, 1983; Howell and others, 1985). Tectonostratigraphic
terranes (hereafter referred to as \"terranes\") are mainly
fault-bounded, stratigraphically coherent assemblages that formed before
accretion to adjacent terranes or to a continental margin. A few
terranes are fault-bounded structural complexes formed in subduction
zones or in accretionary prisms. Terranes are bounded by faults or fault
zones some of which are referred to as sutures. Some sutures are
inferred beneath areas of overlap assemblages or from juxtaposition of
contrasting geologic sequences. Paleontologic, stratigraphic, and
paleomagnetic evidence suggests that some terranes were originally
widely separated from one another, and (or) from cratonal North America
by distances of up to thousands of kilometers. In contrast for other
terranes, paleontologic, stratigraphic, and paleomagnetic evidence
suggests that they are displaced from one another, or from another loci
on the same continent by distances that are greater than the dimensions
of terranes to

greater than hundreds of kilometers. Definitions of tectonic terms are
discussed and defined below.

Inferred tectonic environments of terranes are defined below and
depicted on the map. These environments are: (1) cratonal margin; (2)
passive continental margin; (3) metamorphosed continental margin; (4)
continental margin arc; (5) island arc; (6) turbidite basin; (7) oceanic
crust, sea mount, and ophiolite; (8) accretionary wedge and subduction
zone; and (9) metamorphic. For terranes with varying geologic history,
the chosen tectonic environment indicates the dominant tectonic
environment interpreted for the older sequences of rocks in the terrane.
The tectonic environments inferred for plutonic rocks are described in
relation to associated accretionary events. These environments are pre-
and post-accretion.

Upper Mesozoic sedimentary rocks and Upper Cretaceous and Cenozoic
sedimentary and volcanic rocks are also shown. These rocks are products
of magmatism and sedimentation that occurred mainly after accretion of
many terranes in the late Mesozoic or Cenozoic. Some of the Late
Cretaceous and early Cenozoic igneous and sedimentary rock units, as
well as fragments of terranes, are offset as much as 400 km by movement
along post-accretion faults. Rock units that occur as overlap
assemblages on two or more adjacent terranes provide minimum ages on the
timing of accretion of terranes. For simplicity, the map does not depict
some post-accretion, mainly Cenozoic age faults that occur within
terranes, such as the Hines Creek and Tozitna faults. The time scale
used in this report is that of Palmer (1983).

The basic outcrop pattern and distribution of tectonostratigraphic
terranes for the map are from Beikman (1980), Jones and others (1987),
Monger and Berg (1987), Dusel-Bacon (1991), Grantz and others (1991),
Gehrels and Berg (1992), Moore and others (1992), Reed and others
(written commun., 1993), cited references, and the authors and
contributors. The outcrop pattern and age classification of Cenozoic and
older igneous rocks is modified from T.P. Miller (written commun.,
1991), D.A. Brew (written commun., 1989, 1990, 1991), Dusel-Bacon
(1991), Moll-Stalcup (1990), and E.J. Moll-Stalcup (written commun.,
1991).

**TECTONIC DEFINITIONS**

The following definitions, arranged in alphabetical order, are adapted
from Coney and others (1980), Jones and others (1983), Howell and others
(1985), Monger and Berg (1987), and Wheeler and McFeely (1991), with
modifications by the authors.

*Accretion.* Tectonic juxtaposition of two or more terranes, or tectonic
juxtaposition of a terrane(s) to a continental margin.

*Accretionary-wedge terrane*. Fragment of a mildly to intensely deformed
complex of turbidite deposits and variable amounts of oceanic rocks.
Divided into units composed dominantly of turbidites or of oceanic
rocks. Formed adjacent to zones of thrusting and subduction along the
margin of a continental or an island arc. Commonly associated with
subduction zone terranes. May include large, fault-bounded units with
coherent stratigraphy. Examples are the Chugach and Prince William
terranes.

*Craton margin.* Late Proterozoic up through Jurassic sedimentary rocks
deposited on a continental shelf or slope. Locally has, or is inferred
to have had, an Archean and Early Proterozoic craton basement. Consists
dominantly of platform successions.

*Cratonal terrane.* Fragment of a craton. An example is the Kilbuck
terrane.

*Continental-margin arc terrane.* Fragment of an igneous belt of coeval
plutonic and volcanic rocks, and associated sedimentary rocks that
formed above a subduction zone dipping beneath a continent. Inferred to
have a sialic basement. Examples are the Aurora Peak and Maclaren
terranes.

*Island (intraoceanic) arc terrane.* Fragment of an igneous belt of
plutonic rocks, coeval volcanic rocks, and associated sedimentary rocks
that formed above an oceanic subduction zone. Inferred to possess a
simatic basement. An example is the Wrangellia composite terrane.

*Metamorphic terrane.* Fragment of a highly metamorphosed and (or)
deformed assemblage of sedimentary, volcanic, and (or) plutonic rocks
that cannot be assigned to a single tectonic environment because
original stratigraphy and structure are obscured. Includes highly
deformed structural melanges that contain intensely-deformed pieces of
two or more terranes. Examples are the Behm Canal, Broad Pass, and Windy
terranes.

*Metamorphosed continental-margin terrane.* Fragment of a passive
continental margin, sometimes highly metamorphosed and deformed, that
cannot be linked with certainty to the nearby craton margin, but may be
derived from a distant site from the nearby craton margin, or from
elsewhere. Examples are the Coldfoot, Ruby, Seward, and Yukon-Tanana
terranes.

*Oceanic crust , seamount, and ophiolite terrane.* Fragment of part or
all of a suite of eugeoclinal, deep-marine sedimentary rocks, pillow
basalts, gabbros, and ultramafic rocks that are interpreted as oceanic
sedimentary and volcanic rocks, and upper mantle. Includes both inferred
offshore ocean and marginal ocean basin rocks, minor volcaniclastic
rocks of magmatic arc derivation, and major marine volcanic
accumulations formed at a hot spot, fracture zone, or spreading center.
Mode of emplacement onto continental margin uncertain. Examples are the
Angayucham and Seventymile terranes.

*Overlap assemblage.* A post-accretion unit of sedimentary and (or)
igneous rock units deposited on, or intruded into two or more adjacent
terranes. The sedimentary and volcanic parts depositionally overlie, or
are interpreted to have originally depositionally overlain two or more
adjacent terranes, or terranes and the craton margin. Plutonic rocks, in
some areas, are coeval and genetically related to overlap volcanic
rocks, and weld or stitch together adjacent terranes, or a terrane and a
craton margin. The major overlap assemblages in Alaska are mainly Late
Jurassic and younger sedimentary, volcanic, and plutonic assemblages
that formed during or after the Mesozoic accretion of most of these
terranes. An example of an overlap assemblage is the Cenozoic igneous
rocks of the Aleutian arc that overlap the Chugach and Peninsular
terranes.

*Passive continental-margin terrane.* Fragment of a craton margin. An
example is the Nixon Fork terrane.

*Post-accretion rock unit.* Suite of sedimentary, volcanic, or plutonic
rocks that formed in the late history of a terrane, after accretion. May
occur also on an adjacent terrane(s) or on craton margin as an overlap
assemblage unit. A relative time term denoting rocks formed after
tectonic juxtaposition of one terrane to an adjacent terrane.

*Pre-accretion rock unit.* Suite of sedimentary, volcanic, and (or)
plutonic rocks that formed in the early history of a terrane, before
accretion. Constitutes the stratigraphy and igneous geology inherent to
a terrane. A relative time term denoting rocks formed before tectonic
juxtaposition of one terrane to an adjacent terrane.

*Seamount and oceanic plateau.* Major marine volcanic accumulations
formed at a hot spot, fracture zone, or spreading center.

*Subduction-zone terrane.* Fragment of variably to intensely deformed
oceanic crust and overlying units, oceanic mantle, and lesser turbidite
and continental margin rocks that were tectonically juxtaposed in a zone
of major thrusting of one lithosphere plate beneath another. Divided
into units composed dominantly of turbidites or of oceanic crustal
rocks. Many subduction zone terranes contain fragments of oceanic crust
and associated rocks that exhibit a complex structural history, occur in
a major thrust zone, and possess blueschist facies metamorphism.
Commonly associated with accretionary wedge terranes. May include large,
fault-bounded blocks with coherent stratigraphy. An example is the
McHugh Complex in the northern Chugach terrane.

*Subterrane.* Fault-bounded unit within a terrane that exhibits a
similar but not identical geologic history relative to another
fault-bounded unit in the same terrane.

*Superterrane.* An aggregate of terranes that is interpreted to share
either a similar stratigraphic kindred or affinity, or a common geologic
history after accretion (Moore, 1992). An approximate synonym is
*composite terrane* (Plafker, 1990).

*Terrane.* A fault-bounded geologic entity or fragment that is
characterized by a distinctive geologic history that differs markedly
from that of adjacent terranes (Jones and others, 1983; Howell and
others, 1985). Constitutes a physical entity, i.e., a stratigraphic
succession bounded by faults, inferred faults, or an intensely-deformed
structural complex bounded by faults. Some terranes may be interpreted
as faulted facies equivalents of the same or other terranes with the
original intervening facies changes having been removed during faulting.

*Turbidite-basin terrane.* Fragment of mainly orogenic forearc, backarc,
or tectonic basin of terrigenous-clastic basin deposits. Includes
continental-slope and rise-turbidite deposits, and submarine-fan
turbidite deposits deposited on oceanic crust. May include minor
epiclastic and volcaniclastic deposits. An example is the Manley
terrane.

**ACKNOWLEDGMENTS**

We thank our many colleagues over the years for their many discussions
of Alaskan geology: J.N. Aleinikoff, H.C. Berg, W.P. Brosge, R.M.
Chapman, Michael Churkin, Jr., P.J. Coney, Bela Csejtey, Jr., R.L.
Detterman, J.H. Dover, J.A. Dumoulin, J.T. Dutro, Jr., G.E. Gehrels,
W.G. Gilbert, C.S. GrommŽ, J.W. Hillhouse, Travis Hudson, D.L. Jones,
M.A. Lanphere, R.A. Loney, W.C. McClelland, E.M. MacKevett, Jr., J.W.H.
Monger, J.C. Moore, T.L. Pavlis, B.L. Reed, D.H. Richter, S.M. Roeske,
N.J. Silberling, T.E. Smith, D.B. Stone, I.L. Tailleur, A.B. Till, W.K.
Wallace, F.H. Wilson, and G.R. Winkler. We thank A.B. Till and J.A.
Dumoulin for providing unpublished data on the Seward and York terranes
on the Seward Peninsula, and J.H. Dover for providing unpublished data
and interpretations for east-central Alaska. We also thank J.P. Calzia
and N.J. Silberling for their constructive and thoughtful reviews, and
J.A. Nokleberg for coloring of the map.

> **DESCRIPTION OF STRATIFIED MAP UNITS POST-ACCRETION SEDIMENTARY
> ROCKS**

Qs **Sedimentary rocks (Quaternary)Ñ**Chiefly Quaternary continental
sedimentary rocks and lesser volcanic rocks, and unconsolidated silt,
sand, and gravel. Depositionally overlie older overlap assemblages and
terranes. Locally folded and faulted

Ts **Sedimentary rocks (Tertiary)Ñ**Chiefly Tertiary continental
sedimentary rocks and lesser volcanic rocks. Depositionally overlie
older overlap assemblages and terranes. Locally folded and faulted

Czs **Sedimentary rocks (Cenozoic)Ñ**Chiefly Tertiary continental
sedimentary rocks and lesser volcanic rocks, and Quaternary (including
Holocene) sedimentary rocks and unconsolidated silt, sand, and gravel.
Depositionally overlie older overlap assemblages and terranes. Locally
intensely folded and faulted

Ks **Sedimentary rocks (Cretaceous)Ñ**Chiefly deep marine shale and
minor conglomerate deposited by turbidity currents. Local coarse-grained
sandstone, and fine-grained sedimentary rocks deposited in deep-marine
conditions to shallow-marine to nonmarine conditions. Local interlayered
volcanic rocks chiefly rhyolite, dacite, and andesite tuff, flows, and
breccia. Depositionally overly older Mesozoic overlap assemblages, and
terranes. Locally intensely folded and faulted. In southwestern Alaska,
consists chiefly of Upper Cretaceous Kuskokwim Group (Cady and others,
1955; Box and Elder, 1992) that is mainly shale and fine- to
medium-grained sandstone, and lesser siltstone and conglomerated that
formed as deep-water marine turbidites with abundant, immature,
lithic-rich components. Kuskokwim Group forms major overlap assemblage
on Dillinger, Goodnews, Nixon Fork, Ruby, Tikchik, and Togiak terranes.
In west-central Alaska in the Yukon-Koyukuk basin unit consists mainly
of Lower Cretaceous, deep-marine turbidite deposits and Upper
Cretaceous, shallow marine and non-marine deltaic sedimentary rocks that
overlie Angayucham, Nixon Fork, and Ruby terranes (Nilsen, 1989)

GN **Gravina-Nutzotin overlap assemblage (mid-Cretaceous to Late
Jurassic)Ñ**Chiefly argillite, graywacke, and conglomerate, with lesser
andesitic and basaltic volcanic, and volcaniclastic rocks of the Chisana
Formation, Douglas Island Volcanics, and similar unnamed volcanic units.
Sedimentary rocks range from deep marine turbidites to shallow-water and
nonmarine deposits. In eastern-southern Alaska, coarse clastic rocks in
Nutzotin part of assemblage derived locally from the underlying
Wrangellia terrane and from unknown metamorphic source terranes. In
southeastern Alaska, coarse clastic rocks in Gravina part of assemblage
derived from stratigraphically underlying Alexander and Wrangellia
terranes mainly to west, but may also have been derived in part from the
Stikinia, Wrangellia, and Yukon Tanana terranes to the east. Nutzotin
and correlated Gravina parts of assemblage apparently deposited in
separate basins. Gravina-Nutzotin overlap assemblage correlated with the
Kahiltna overlap assemblage to west. Locally intensely faulted and
folded. Intruded by mid- and Late Cretaceous granitic, gabbroic, and
ultramafic rocks, part of Chisana, Chitina, and Glacier Bay-Chichagof
arcs, and by younger granitic rocks. In southeastern Alaska, Gravina
part of unit forms an extensive overlap assemblage that overlies
Alexander and Wrangellia terranes, and is locally overthrust by the
Yukon Prong and Behm Canal terranes to the east. **REFERENCES**: Berg
and others, 1972; Richter, 1976, Barker, 1987; Brew and Karl, 1988a, b,
c; Ford and Brew, 1988; Gehrels and others, 1990; McClelland and others,
1991; Haeussler, 1992

KA **Kandik River overlap assemblage (Early Cretaceous, Jurassic, and
Late Triassic)Ñ**Chiefly Upper Triassic, Jurassic, and Lower Cretaceous
shelfal shale and quartzite (Glenn Shale, Keenan Quartzite) overlain by
mainly flyschoid graywacke and non-marine molasse strata that are
recycled foreland basin deposits (Biederman Argillite, and Kathul
Graywacke). Generally broadly folded with local, small isoclinal folds.
Kandik overlap assemblage thrust onto miogeoclinal margin of western
North America along northwest-dipping thrusts. Isoclinally folded and
with low-grade regional metamorphism. Kandik River overlap assemblage
interpreted as a faulted overlap assemblage originally deposited on
Porcupine terrane to northwest, and possibly also deposited on North
American craton margin. Structurally overlain by Angayucham and
Porcupine terranes along northwest-dipping thrusts. **REFERENCES:**
Brabb and Churkin, 1969; Churkin and others, 1982; Howell and Wiley,
1987; Dover, 1990; Howell and others, 1992

KH **Kahiltna overlap assemblage (Cretaceous and Late
Jurassic)Ñ**Chiefly deep marine, partly volcaniclastic, flyschoid
graywacke and argillite, with minor amounts of chert, limestone,
conglomerate, and andesite. Mainly Early Cretaceous age, but includes
rocks ranging in age from Late Jurassic to early Late Cretaceous
(Cenomanian). Structurally-disrupted and intensely folded and faulted.
Metamorphic grade mainly lower greenschist facies, but ranges from
zeolite to amphibolite facies. Occurs north of Peninsular terrane and
interpreted to depositionally overlie Peninsular terrane on Alaska
Peninsula. Thrust over Wrangellia terrane in central Alaska Range. May
comprise part or all of Maclaren Glacier metamorphic belt of the
Maclaren terrane in eastern Alaska Range. In southwestern Alaska,
Kahiltna overlap assemblage interpreted to be depositionally overlain by
Upper Cretaceous marine sedimentary rocks of Kuskokwim Group to north.
Local Late Cretaceous (Turonian) strata in poorly mapped areas may
represent gradation into Upper Cretaceous Kuskokwim Group. Correlated
with Gravina part of Gravina-Nutzotin overlap assemblage to east and
southeast. Contains several, small terranes including Broad Pass,
Chulitna, Susitna, and West Fork terranes. Former Kahiltna terrane of
Jones and others (1981, 1987). **REFERENCES**: Jones and others, 1981,
1987; Wallace and others, 1989; Csejtey and others, 1992

> **POST-ACCRETION CENOZOIC AND LATE CRETACEOUS VOLCANIC ROCKS**
>
> *(Note: Felsic includes Siliceous and intermediate igneous rocks.)*

QTv f **Felsic volcanic rocks (Quaternary and late Tertiary)Ñ**Younger
than 30 Ma. Chiefly andesite, dacite, and rhyolite of the eastern
Aleutian arc and the Wrangell volcanic field. In southeastern Alaska,
includes Kuiu-Etolin bimodal volcanic belt.

QTvm **Mafic volcanic rocks (Quaternary and late Tertiary)Ñ**Younger
than 30 Ma. In western Alaska, the Bering Sea shelf, and the Bering Sea
Islands, chiefly widespread alkali olivine and tholeiitic basalt and
minor basinite and nephelanite of the Bering Sea volcanic belt. In
eastern Alaska, chiefly alkalic and tholeiitic basalt of the
Yukon-Porcupine Flats, and small basanite and basalt cinder cones
erupted throughout the Yukon-Tanana terrane. In southern Alaska, chiefly
basalt and basaltic andesite of the eastern Aleutian arc and Wrangell
volcanic field. In southeastern Alaska, chiefly calc-alkalic Edgecomb
volcanic field and the Behm Canal basalts

mTv f **Felsic volcanic rocks (middle Tertiary)**ÑBetween 30 and 55 Ma.
Chiefly andesite and dacite flows and tuffs, and minor basalt and
rhyolite that were erupted along the southern margin of Alaska as part
of an older pulse of Aleutian magmatism. In western interior Alaska,
chiefly small rhyolite bodies with ages of about 40 Ma age that are
associated with more mafic rocks. Unit forms the Interior Alaska,
West-Central, and Saint Lawrence Island volcanic belts

mTvm **Mafic volcanic rocks (middle Tertiary) Ñ**Between 30 and 55 Ma.
Chiefly basalt and basaltic andesite erupted during an earlier pulse of
magmatism in the eastern Aleutian arc. Also includes a small field in
western Alaska of basalt and alkali rhyolite erupted at the end of
subduction-related magmatism at about 55 Ma

TKv f **Felsic volcanic rocks (early Tertiary and Late
Cretaceous)**ÑBetween 55 and 76 Ma; locally as old as 93 Ma in
east-central Alaska. Chiefly rhyolite, dacite, and andesite tuffs and
flows comprising a widespread, continental-margin magmatic arc in
western, southwestern, and southern Alaska. In interior and southern
Alaska, unit forms felsic volcanic part of the Alaska Range-Talkeetna
Mountains, Kuskokwim Mountains, and Yukon-Kanuti volcanic-plutonic belts

TKvs **Siliceous volcanic rocks (early Tertiary and Late
Cretaceous)**ÑBetween 55 and 76 Ma; locally as old as 93 Ma in
east-central Alaska. In western and southern Alaska, chiefly rhyolite
and dacite tuffs and flows comprising the most chemically-evolved part
of a widespread, continental-margin magmatic arc. In east-central
Alaska, chiefly rhyolite and dacite tuffs and flows. In interior and
southern Alaska, unit forms silicic volcanic part of the Alaska
Range-Talkeetna Mountains, Kuskokwim Mountains, and Yukon-Kanuti
volcanic-plutonic belts

TKvi **Intermediate volcanic rocks (early Tertiary and Late
Cretaceous)**ÑBetween 55 and 76 Ma. Chiefly andesite and dacite with
subordinate rhyolite flows and tuffs comprising a widespread,
continental-margin magmatic arc in western, southwestern, and southern
Alaska. In interior and southern Alaska, unit forms intermediate,
volcanic part of the Alaska Range-Talkeetna Mountains, Kuskokwim
Mountains, and Yukon-Kanuti volcanic-plutonic belts

> **CRATON MARGIN AND OCEANIC ROCK UNITS**

NAM **North AmericaÑ**Undisplaced stable craton margin. Late Proterozoic
shelfal sedimentary and volcanic strata, chiefly sandstone, shale,
argillite, limestone, dolomite (Tindir Group) deposited under paralic to
glacial margin conditions. Grades upward into lower and middle Paleozoic
carbonate rocks, shale, and chert (Funnel Creek Limestone, Adams
Argillite, Hillard Limestone, Road River Formation, McCann Hill Chert,
Nation River Formation, and Ford Lake Shale) deposited during a major
marine transgression and foundering of continental margin after rifting
at about 570 Ma. Younger, upper Paleozoic through mid-Cretaceous
shallow-marine to shelfal deposits (Calico Bluff Formation, Tahkandit
Limestone, and Glenn Shale). Structurally underlies Kandik River
assemblage along northwest-dipping thrusts. Includes the shallow-marine
platform deposits of Yukon Territory and Mackenzie District that
depositionally onlap the crystalline rocks of the Canadian Shield.
Northwest extension of nuclear North America craton margin.
**REFERENCES**: Jones and others, 1981; Howell and Wiley, 1987; Dover,
1990; Howell and others, 1992

PAC **Pacific plateÑ**Late Eocene to late Miocene oceanic crust 7 to 10
km thick overlain by as much as 2.5 km of Eocene to Holocene pelagic,
hemipelagic, continental-rise, and glacio-marine deposits. Seismic
refraction data indicate that oceanic mantle is overlain layer 3 about 5
km thick, layer 2 about 1 to 1.5 km thick, and layer 1, from less 200 m
thick in areas distant from the continent, to more than 2 km thick near
the continental margin. Outside of map area, contains chains of sea
mounts (Gilbert, Kodiak, and Patton), fracture zones (Aia, Blanco, Sila,
Sedna, Surveyor, Sovano), and oceanic spreading ridge (Juan de Fuca)
south of southeastern Alaska. **REFERENCES**: Atwater, and Severinghaus,
1991; Grantz and others, 1991; Kirschner, 1988

> **TECTONO-STRATIGRAPHIC TERRANES**
>
> *\[Arranged alphabetically by map symbol; inferred tectonic
> environment in parentheses\]*

**Arctic Alaska superterraneÑ**Consists of Endicott Mountains, De Long
Mountains, Hammond, North Slope, and Tigara terranes. North Slope
terrane occurs along northern margin of Arctic Alaska, Endicott
Mountains, De Long Mountains, and Hammond terranes occur generally
successively to south. Tigara terrane occurs in western Arctic Alaska.
Coldfoot terrane (Moore, 1992; Moore and others, 1992) designated as
separate terrane in this study. Arctic Alaska superterrane generally
overlain by Jurassic and Cretaceous marine sedimentary rocks, and by
Cenozoic marine and continental sedimentary rocks. Various terranes of
Arctic Alaska terrane are interpreted as originally forming in a passive
continental margin environment that subsequently was substantially
tectonically imbricated during major Mesozoic thrusting followed by
local to substantial extension along southern margin (Moore, 1992; Moore
and others, 1993)

AAD **De Long Mountains terrane (passive continental margin)Ñ**Occurs
along length of Brooks Range and consists of at least four allochthonous
sequences that are composed of Upper Devonian or Lower Mississippian to
Lower Cretaceous sedimentary rocks and that are distinguished by various
stratigraphic characteristics. Terrane typically consists of: (1) Upper
Devonian carbonate rocks (Baird Group, part); (2) Lower Mississippian
shallow- to deep-marine clastic rocks and black shale (Kayak Shale of
Endicott Group); (3) Lower Pennsylvanian through Triassic chert and
argillite (Etivluk Group), and (or) Mississippian carbonate platform
rocks (Lisburne Group); and (4) Upper Jurassic and Lower Cretaceous
(Neocomian) flysch (Okpikruak Formation). Individual allochthonous
sequences distinguished by: (1) presence or absence of Upper Devonian
and Mississippian arkosic debris (Nuka Formation) containing 2.06 Ga
clastic zircons; (2) Mississippian and Lower Pennsylvanian
shallow-marine carbonate platform deposits (Lisburne Group); (3)
abundant Permian(?) diabase sills intruding upper Paleozoic strata; and
(4) proportion of clastic material within siliceous Permian, Triassic,
and Lower Jurassic deposits (Etivluk Group). De Long Mountains terrane
structurally overlies Endicott Mountains terrane and is interpreted as a
displaced fragment of the late Paleozoic and early Mesozoic Arctic
continental margin of North America. **REFERENCES**: Jones and others,
1981, 1987; Dumoulin and Harris, 1987; Mayfield and others, 1988; Karl
and others, 1989; Moore and Mull, 1989; Moore and others, 1992

AAE **Endicott Mountains terrane (passive continental margin)Ñ**Occurs
along length of northern Brooks Range and consists of: (1) Upper
Devonian marine shale and sandstone (Hunt Fork Shale, Noatak Sandstone,
part) grading upwards into thick coarse-grained uppermost Devonian and
lowermost Mississippian(?) fluvial deposits (Kanayut Conglomerate), and
capped by transgressive marine shale (Kayak Shale) that comprise
Endicott Group and represent a fluvial-deltaic clastic wedge shed from a
northern and eastern source area using present-day coordinates; (2)
Mississippian and Pennsylvanian continental-margin carbonate platform
deposits (Lisburne Group), and Mississippian and Pennsylvanian shale,
chert, dolomite, and sparse marine keratophyre flow and tuff (Kuna
Formation); (3) Permian to Jurassic siliceous argillite, chert, and
silicified limestone (Siksikpuk and Otuk Formations); and (4) Jurassic
to Lower Cretaceous (Neocomian) shale (Ipewik unit) containing a thin,
but extensive *Buchia* coquina unit. Overlap units are Neocomian
(Okpikruak Formation) and Albian (Fortress Mountain and Torok
Formations) flysch and lutite. Terrane displays chlorite-grade
greenschist facies metamorphism of Mesozoic age at base. Terrane
structurally overlies Hammond and North Slope terranes and underlies De
Long Mountains terrane. Endicott Mountains terrane interpreted as
displaced fragment of the Paleozoic and early Mesozoic Arctic
continental margin of North America. Includes Kagvik terrane of Churkin
and others (1979). **REFERENCES**: Dutro and others (1976); Churkin and
others, 1979; Jones and others, 1981, 1987; Mull and others, 1982;
Nokleberg and Winkler, 1982; Mayfield and others, 1978, 1988; Nilsen,
1981; Karl and others, 1989; Moore and Mull, 1989; Moore and others,
1992

AAH **Hammond terrane (passive continental margin)Ñ**Occurs along length
of central and southern Brooks Range in four complexly imbricated
assemblages: (1) Late(?) Proterozoic quartz-mica schist, quartzite,
marble, calc-schist, metabasalt, and phyllite metamorphosed generally at
lower greenschist facies; (2) metamorphosed Cambrian to Silurian and
older carbonate rocks (Skajit Limestone and undifferentiated Baird
Group); (3) Devonian phyllite, metasandstone, metaconglomerate,
metatuff, metabasalt, and limestone (Beaucoup Formation) and upper
Paleozoic (Mississippian) conglomerate and black shale (Kekiktuk and
Kayak Formations); (4) sparse Mississippian and Pennsylvanian(?)
carbonate platform rocks (Lisburne Group); and (5) sparse siltstone of
Permian(?) and Triassic(?) age (Saddlerochit(?) Group). Older two
assemblages locally intruded by Late Proterozoic and Devonian gneissic
granitic rocks. Hammond terrane characterized by widespread presence of
the second assemblage and a strong structural fabric overprinting relict
primary sedimentary structures. Oldest assemblage exposed in local
structural highs. Upper Paleozoic sequence correlative with coeval
stable shelf deposits of the North Slope terrane. Hammond terrane
displays mainly chlorite-grade greenschist facies metamorphism and
relatively older blueschist and amphibolite facies metamorphism. Hammond
terrane interpreted as a composite of several terranes displaced from
unknown early Paleozoic carbonate platforms and clastic basins along the
North American(?) and (or) Siberian(?) continental margins. Hammond
terrane structurally underlies Endicott Mountains and Coldfoot terranes.
**REFERENCES**: Tailleur and others, 1977; Dillon and others, 1980,
1987; Jones and others, 1981, 1987; Dumoulin and Harris, 1987; Dillon,
1989; Karl and others, 1989; Moore and Mull, 1989; Moore and others,
1992

AAN **North Slope terrane (passive continental margin)Ñ**Occurs in North
Slope subsurface, northeastern Brooks Range, and Doonerak structural
window and consists of three major sequences: Franklinian sequence
(pre-Mississippian), Ellesmerian sequence (Mississippian to Early
Cretaceous), and Brookian sequence (mid-Cretaceous and Cenozoic).

Franklinian assemblage is complexly deformed, stratigraphically
complicated, and may be a composite of several terranes. The best
studied part (illustrated in stratigraphic column) occurs in Sadlerochit
Mountains, on the north flank of the northeastern Brooks Range, and
consists of a carbonate platform to basin assemblage composed of: (1)
Katakturuk Dolomite (Proterozoic), Nanook Limestone (Proterozoic(?) or
lower Cambrian to Ordovician); and (2) Mount Copleston Limestone (Lower
Devonian). Pre-Mississippian rocks elsewhere in terrane consist of Late
Proterozoic through Silurian slate, phyllite, chert, graywacke,
carbonate rocks, mafic and intermediate volcanic and volcaniclastic
rocks, and the Neruokpuk Quartzite. Franklinian sequence contains sparse
Devonian metagranitic plutons.

Ellesmerian sequence unconformably overlies Franklinian sequence and
consists of: (1) transgressive unit of Mississippian nonmarine
conglomerate and marine shale (Kayak Shale and Kekiktuk Conglomerate of
Endicott Group); (2) Mississippian to Permian carbonate platform
deposits (Lisburne Group); (3) Permian and Triassic marine shale,
sandstone and conglomerate (Echooka Formation and Ivishak Formation of
Sadlerochit Group); (4) Triassic black shale, limestone and quartz-rich
sandstone (Shublik Formation) and Jurassic and Lower Cretaceous black
shale and sparse fine-grained sandstone (Kingak Shale).

Brookian sequence disconformably to unconformably overlies the
Ellesmerian sequence and consists of: (1) mid- to Upper Cretaceous
condensed basinal deposits (pebble shale unit and the Hue Shale); and
(2) northeast-prograding fluvial deltaic deposits of mid-Cretaceous age
(Fortress Mountain Formation, Torok Formation, Nanushuk Group, and of
Early Cretaceous and Tertiary age (Canning Formation, Colville Group,
Sagavanirktok Formation). Prograding deltaic deposits separated by
regional Cenomanian disconformity.

North Slope terrane structurally overlain by Endicott Mountains and De
Long Mountains terranes. Base not exposed. North Slope terrane
interpreted as a displaced fragment of the Paleozoic and early Mesozoic
Arctic continental margin of North America. **REFERENCES**: BrosgŽ and
others, 1962; BrosgŽ and Tailleur, 1970; Jones and others, 1981, 1987;
Mull and others, 1982; Bird, 1985, 1988; Blodgett and others (1986,
1988, 1992; Mayfield and others, 1988; Moore and Mull, 1989; Grantz and
others, 1990; Moore and others, 1992

AAT **Tigara terrane (passive continental margin)Ñ**Occurs on Lisburne
Peninsula in northwestern Alaska, and on western tip of Seward Peninsula
in western Alaska and consists of orogenic deposits unconformably
overlain by stable shelf deposits. These deposits are: (1) Ordovician
and Silurian slaty argillite, graptolitic shale, and graywacke
turbidites of the Iviagik Group (Martin (1970) that is more than 1,500 m
thick; (2) unconformably overlying, Lower Mississippian, intercalated
marine and nonmarine argillite, lutite, quartzite, and coal of the
Kapaloak sequence that is more than 600 m thick; (3) Upper(?)
Mississippian marine shale (similar to Kayak Shale) and Lower
Mississippian to Pennsylvanian carbonate rocks of the Nasorak, Kogruk,
and Tupik Formations of Lisburne Group that is about 2,000 m thick; (4)
Pennsylvanian to Jurassic argillite, siliceous shale, and argillaceous
chert of the Etivluk Group that is about 200 m thick; and (5) Upper
Jurassic(?) to Neocomian marine graywacke turbidite and marine mudstone
of the Ogotoruk, Telavirak, and Kismilok Formations that together are
more than 5,100 m thick. Tigara terrane inferred to be overlapped by
Colville Basin deposits, including marine turbidite sandstone and
mudstone that may be part of the Albian Fortress Mountain Formation.
Tigara terrane resembles in part North Slope terrane, and in part
Endicott Mountains terrane (Jones and others, 1987). Tigara terrane may
extend offshore to at least part of the adjacent Herald Arch of the
central Chukchi Sea. In western Brooks Range, terrane may be thrust over
Cretaceous sedimentary rocks to east; in western Seward Peninsula,
thrust over York terrane to east. Tigara terrane interpreted as a
fragment of the displaced Paleozoic and early Mesozoic Arctic
continental margin of North America. **REFERENCES**: Campbell, 1967;
Martin, 1970; Jones and others, 1981, 1987; Murchey and others, 1988;
Grantz and others, 1983, 1991; Moore and others, 1992

AM **Angayucham terrane (subduction zone - dominantly oceanic
rocks)Ñ**Occurs in east- and west-central, and southwestern Alaska,
along southern flank of Brooks Range, and in large klippen in western
Brooks Range. Divided into lower (Slate Creek), middle (Narvak), and
upper (Kanuti) thrust panels.

**Lower (Slate Creek) thrust panel**ÑChiefly phyllonite, melange, and
sedimentary broken formation. Sedimentary part consists mainly of
thin-bedded, quartz-rich and chert-rich graywacke turbidites of
continental derivation, chert, phyllite, slate. Local tectonic blocks of
volcanic rocks, chert, limestone turbidite, chert-pebble conglomerate,
and shallow marine clastic deposits. Contains palynomorphs, conodonts,
radiolarians, brachiopods and plant fragments ranging in age from
Devonian to Early Jurassic. Locally to pervasively deformed and
metamorphosed to lower greenschist facies in Mesozoic time, particularly
along northern margin where phyllonite is common. Slate Creek thrust
panel includes both Prospect Creek, Slate Creek, and Venetie terranes of
Grantz and others (1991) and Moore and others (1992); interpreted as a
tectonic unit that separates structurally underlying, regionally
metamorphosed and deformed rocks of Coldfoot, Endicott, Hammond
Mountains, and Ruby terranes from overthrust oceanic rocks of Narvak
thrust panel. **REFERENCES**: Jones and others, 1987; Murphy and Patton,
1988; Moore and Mull, 1989; Moore and Murphy, 1989; Patton and others,
1989, 1992; Dover, 1990; Grantz and others, 1991; Patton, 1992a, b;
Moore and others, 1992.

**Middle (Narvak) thrust panelÑ**Chiefly structurally interleaved
diabase, pillow basalt, tuff, chert, graywacke, argillite, minor
limestone, and volcanogenic sandstone, conglomerate, and tuff. Locally
abundant gabbro and diabase. Cherts range in age from Late Devonian to
Early Jurassic. Limestones mainly Carboniferous. Devonian corals,
brachiopods, and graptolites from shale and limestone beds in extreme
eastern Alaska. Major accumulations of late Carboniferous and Late
Triassic basaltic volcanism; however, many volcanic sequences are not
yet well dated. Basalts interpreted as oceanic island or plateau basalt
based on associated sedimentary facies and trace-element discriminant
patterns. Includes Tozitna, Innoko, and Woodchopper Canyon terranes of
Jones and others (1981, 1987) and Grantz and others (1991), and Rampart
Group of east-central Alaska.

Narvak thrust panel structurally and stratigraphically complex;
generally highly faulted and locally folded. Metamorphosed to
greenschist facies and locally blueschist facies, as indicated by
glaucophane, at base of thrust panel. Narvak thrust panel structurally
overlies Coldfoot terrane to north and Ruby terrane to south;
structurally overlain by Koyukuk terrane, and locally in southwestern
Alaska, protolith forms stratigraphic basement to Koyukuk terrane.
Narvak thrust panel depositionally overlain by Cretaceous clastic
deposits of Yukon-Koyukuk Basin, and by Late Cretaceous and early
Tertiary Yukon-Kanuti and Kuskokwim Mountains igneous belts. Narvak
thrust panel interpreted as a subduction zone complex composed chiefly
of oceanic crust and seamounts. Locally in southwestern Alaska, Narvak
thrust panel may be stratigraphically overlain by rocks of Koyukuk
terrane. **REFERENCES**: BrosgŽ and others, 1969; Murchey and Harris,
1985; Barker and others, 1988; Jones and others, 1988; Pallister and
Carlson, 1988; Pallister and others, 1989; Patton and others, 1977,
1989, 1992; Patton, 1992a, b.

**Upper (Kanuti) thrust panelÑ**Chiefly serpentinized pyroxenite,
harzburgite, dunite, wehrlite, and gabbro with cumulate and tectonic
structures, and intrusive gabbro and diabase. Basal contact of ophiolite
locally marked by amphibolite metamorphosed at the time of structural
emplacement in the Middle Jurassic (Boak and others, 1987). Includes
Misheguk Mountain terrane of Grantz and others (1991) and other isolated
klippen of ultramafic and mafic rocks structurally overlying Narvak
thrust panel. Kanuti thrust panel interpreted as part of an ophiolitic
assemblage emplaced during Middle or Late Jurassic onto an apparently
unrelated middle (Narvak) thrust panel of basalt and oceanic sedimentary
rocks that constitute the root of an island arc, possibly the
tectonically suprajacent Koyukuk terrane. **REFERENCES**: Patton and
others, 1977, 1989; 1992; Wirth and others, 1986; Boak and others, 1987;
Loney and Himmelberg, 1985, 1989; Mayfield and others, 1988; Karl, 1992;
Patton, 1992a, b

AP **Aurora Peak terrane (continental margin arc)Ñ**Occurs in eastern
and central Alaska Range and consists of Silurian through Triassic
metasedimentary rocks, and Late Cretaceous and early Tertiary
metagranitic rocks. Older metasedimentary rocks consist mainly of fine-
to medium-grained and polydeformed calc-schist, marble, quartzite, and
pelitic schist. One conodont fragment from marble indicates a Silurian
to Triassic age. Protoliths for metasedimentary rocks include marl,
quartzite, and shale. Correlated with Kluane Schist in southwest Yukon
Territory. Younger metaplutonic sequence (unit Kpf) consists of
regionally metamorphosed and penetratively deformed schistose quartz
diorite with granodiorite, granite, and sparse amphibolite derived from
gabbro and diorite. U-Pb zircon and Rb-Sr whole-rock isochron isotopic
analyses of the metaplutonic rocks indicate emplacement ages of 71 and
74 Ma. Isotopic analysis of lead from samples of metagranitic rocks show
moderate radiogenic values, and derivation from a source of about 1.2-Ga
age.

> Minimum structural thickness of terrane several thousand meters.
> Terrane is twice ductily metamorphosed and deformed. Core of terrane
> exhibits older, upper amphibolite facies metamorphism and associated
> mylonitic schist. Upper amphibolite facies metamorphism probably
> occurred during syntectonic intrusion of the Late Cretaceous
> metagranitic rocks. Margin of terrane exhibits younger middle
> greenschist facies metamorphism and formation of blastomylonite along
> an intense, younger schistosity. Younger greenschist facies minerals
> and younger intense schistosity occur mainly along the margins of the
> terrane, adjacent to bounding Denali and Nenana Glacier faults. Aurora
> Peak terrane interpreted as a displaced fragment of a North American
> continental-margin arc that was tectonically separated from the Kluane
> Schist and the Ruby Range batholith in southwestern Yukon Territory.
> **REFERENCES**: Brewer, 1982; Nokleberg and others, 1985, 1989a, 1992;
> Aleinikoff and others, 1987

BC **Behm Canal (metamorphic)Ñ**Occurs in eastern southeastern Alaska
and consists of structurally interleaved thrust slices of
Gravina-Nutzotin overlap assemblage, Alexander, Wrangellia, Stikinia,
and Yukon-Tanana terranes, Alava sequence of Rubin and Saleeby (1991),
Kah Shakes sequence of Saleeby and Rubin (1990) and Rubin and Saleeby
(1991), and Ruth assemblage of McClelland and Gehrels (1990). Chiefly
mica schist, granitic orthogneiss, calc-silicate rocks, siliceous
paragneiss, minor marble and amphibolite. Alava sequence consists of
crinoidal and argillaceous marble, carbonaceous phyllite, argillite,
mafic flows, pillow breccia, tuff, and quartzite of late Paleozoic and
Middle and Late Triassic age that are correlated by Rubin and Saleeby
(1991) with rocks of the Stikinia terrane. Behm Canal terrane
metamorphosed to greenschist- to amphibolite-facies in the Late
Cretaceous and Early Tertiary, after accretion. Intruded by middle and
Late Cretaceous granitic, gabbroic, and ultramafic rocks, and by Late
Cretaceous and Early Tertiary intermediate plutonic rocks. Includes part
of the former Taku terrane of Monger and Berg (1987). Locally
structurally overlain by the lower Paleozoic Kah Shakes sequence and an
early Paleozoic Behm Canal gneiss complex that are both interpreted as
part of the Yukon Prong terrane in southeastern Alaska. Behm Canal
terrane interpreted as a series of interleaved fault slices of various
adjacent terranes. **REFERENCES**: Saleeby and Rubin, 1990; Rubin and
Saleeby, 1991

BP **Broad Pass terrane (metamorphic)Ñ**Occurs in central Alaska Range
as a structural melange composed chiefly of chert, argillite, phyllite,
bedded tuff, limestone, and flysch including graywacke, argillite, and
chert-pebble and polymictic conglomerate. Chert contains Late
Devonian(?) to Mississippian radiolarians, and limestone blocks contain
Silurian and Devonian fossils (Jones and others, 1980). Poorly exposed
and structurally complex. One of several mini-terranes enclosed in
highly-deformed flysch of the Kahiltna overlap assemblage. Broad Pass
terrane interpreted as a structural melange of diverse metasedimentary
rocks that formed during Cretaceous deformation of enclosing Kahiltna
overlap assemblage. **REFERENCES**: Jones and others, 1982; Csejtey and
others, 1992

**Chugach terrane (accretionary wedge and subduction zone)Ñ**Composite
terrane in Chugach Mountains between Border Ranges and Contact faults in
southern Alaska. In southern Alaska consists of: (1) a northern unit of
blueschist and greenschist; (2) a central unit of McHugh Complex and
correlative units; and (3) a southern unit of the Valdez Group and
correlative units. These three units have counterparts in southeastern
Alaska

**Blueschist and greenschist (subduction zone, dominantly oceanic
rocks)Ñ**Chiefly narrow, fault-bounded units of blueschist and
interlayered greenschist too small to depict on map (schists of Liberty
Creek, Iceberg Lake, Seldovia, and Raspberry Strait). Blueschist and
greenschist unit occurs in narrow, intensely-deformed, fault-bounded
lenses mainly along northern or inboard margin of McHugh Complex and
correlative units. Metamorphosed from blueschist to transitional
greenschist-blueschist facies. Early Jurassic U-Pb sphene, Ar-Ar, and
Rb-Sr mineral isochron metamorphic ages. Interlayered blueschist and
greenschist units interpreted as discontinuous remnants of a subduction
zone assemblage associated with formation of Jurassic Talkeetna arc to
the north

CGM **McHugh Complex and correlative units (subduction zone, dominantly
oceanic rocks)Ñ**Chiefly a Mesozoic subduction zone melange composed of
mainly Late Triassic, Jurassic, and Early to mid-Cretaceous argillite,
basalt, graywacke, radiolarian chert, and limestone, with sparse
conglomerate, pillow basalt, mafic tuff, volcanic rocks, and plutonic
rocks, and with exotic blocks of ultramafic rocks, and limestone.
Includes McHugh and Uyak Complexes, Kelp Bay Group, and unnamed chert
and basalt of Kachemak Bay previously interpreted as the Kachemak
terrane by Jones and others (1987). Some limestone blocks contain
Permian Tethyan fusulinids. Metamorphosed from prehnite-pumpellyite to
lower greenschist facies. McHugh Complex and correlative units intruded
by Middle Cretaceous trondhjemite and by early and middle Tertiary
granitic plutonic rocks in outcrops that are too small to depict on map.
McHugh and correlative units interpreted as disrupted oceanic crust, sea
mount, and (or) trench fill assemblages. Subduction linked to Early and
middle Jurassic Talkeetna arc, and to Late Jurassic and Early Cretaceous
Chitina and Chisana arcs to north

CGV **Valdez Group and correlative units (accretionary wedge -
dominantly turbidites)Ñ**Chiefly an accretionary complex composed of
Upper Cretaceous (Campanian to Maastrichtian) flysch, mainly graywacke
and slate of Valdez Group, Kodiak and Shumagin Formations, Sitka
Graywacke, and unnamed metamorphic equivalents. Sparse megafossils.
Local thick metabasalt sequence along southern margin. Generally
exhibits lower greenschist metamorphism. Complexly folded and faulted.
Metamorphic grade increases to upper amphibolite facies in the
informally named Chugach metamorphic complex of Hudson and Plafker
(1982) in eastern Chugach Mountains. In this area, granitic intrusive
rocks of Sanak Baranof plutonic belt (50-65 Ma), and associated aureoles
of amphibolite facies metamorphism weld Chugach terrane to the adjacent
northern Prince William terrane by early Eocene. Elsewhere locally,
early Tertiary plutons are truncated by Contact fault between the
Chugach and Prince William terranes. In southern Alaska, bounded to
north by Border Ranges fault and Peninsular and Wrangellia terranes.
Bounded to south and west by Contact fault and Prince William terrane.
Valdez Group and correlative units interpreted as trench deposit derived
from a Cretaceous magmatic arc to the north and east (present-day
coordinates), and partly as an intraoceanic accreted primitive arc.
**REFERENCES**: Connelly, 1978; Connelly and Moore, 1979; Decker and
others, 1980; Hudson and Plafker, 1982; Johnson and Karl, 1985; Brew and
others, 1988; Roeske and others, 1989; Plafker and others, 1989b; Sisson
and others, 1989; Karl and others, 1990; Lull and Plafker, 1990; Bradley
and Kusky, 1992; Nelson, 1992

CH **Chulitna terrane (ophiolite)Ñ**Occurs in central Alaska Range and
consists of four major units: (1) Late Devonian ophiolite composed of
serpentinite, gabbro, pillow basalt, and red radiolarian chert; and
Mississippian chert; (2) Permian volcanic conglomerate, limestone,
chert, and argillite; (3) Lower Triassic limestone; (4) Upper Triassic
redbeds, including red sandstone, siltstone, argillite, and
conglomerate, and pillow basalt, limestone, sandstone, and shale; and
(5) Jurassic argillite, sandstone, and chert. Depositional contacts and
(or) reworked clastic detritus form underlying rocks indicate a
continuous stratigraphic sequence. Ammonites from Lower Triassic
limestone show strong affinities with faunas from California, Nevada,
and Idaho, but differ from assemblages in Canada. Terrane moderately to
intensely folded and thrust-faulted and structurally overlies highly
deformed upper Mesozoic argillite and graywacke of the Kahiltna overlap
assemblage to west, and West Fork terrane to east. Chulitna terrane
interpreted as an allochthonous fragment of an ophiolite and overlying
igneous arc and sedimentary sequence. **REFERENCES**: Nichols and
Silberling, 1979; Jones and others, 1980; Csejtey and others, 1992

CO **Coldfoot terrane (metamorphosed continental margin)Ñ**Occurs along
southern margin of Brooks Range and consists of two major units: (1) a
structurally high sequence Late Proterozoic(?) to Cambrian(?)
quartz-mica schist, quartzite, mica schist, and minor metamorphosed
felsic and mafic volcanic rocks; and (2) a structurally low sequence of
calc-schist and marble with local Silurian and Devonian conodonts, and
locally the Devonian Ambler sequence forms in central and western Brooks
Range composed of metamorphosed rhyolite and basalt volcanic flows,
tuff, and breccia with stratiform massive sulfide deposits interlayered
with chlorite schist, marble, calcschist, and graphitic schist. Terrane
contains local metagabbro and metadiabase dikes and sills of middle
Paleozoic(?) age. In central Brooks Range younger unit exposed in local
structural windows beneath older unit. Terrane locally intruded by
Devonian and Late Proterozoic granitic plutons metamorphosed to
orthogneiss. Terrane informally named the *schist belt*.

Polymetamorphosed and deformed in Late Mesozoic and older(?) time.
Terrane exhibits relict regional Mesozoic blueschist facies minerals
overprinted by pervasive lower to middle greenschist facies minerals.
Local areas of Late Proterozoic(?) amphibolite facies metamorphism.
Local intense retrogressive metamorphism and deformation with formation
of phyllonite at structural top adjacent to structurally overlying
Angayucham terrane. Structurally overlies Hammond terrane to north,
structurally overlain by Angayucham terrane to south. Coldfoot terrane
correlated with Seward terrane to southwest. Coldfoot terrane
interpreted as an intensely metamorphosed and deformed, displaced
fragment of the North American craton margin. **REFERENCES**: Armstrong
and others, 1986; Hitzman and others, 1982; Till and others, 1988;
Dillon, 1989; Karl and others, 1989; Moore and Mull, 1989; Gottschalk,
1990; Karl and Aleinikoff, 1990; Moore and others, 1992; Patton and
others, 1992

CW **Clearwater terrane (island arc)Ñ**Occurs in east-central Alaska and
consists of a structurally complex assemblage of argillite, greenstone
(pillow basalt), marble derived from shallow-water limestone, and
metarhyolite. Marble contains Late Triassic (late Norian) fossils.
Contains fault-bounded pluton of Cretaceous(?) granodiorite. Weakly
metamorphosed and penetratively deformed at lower greenschist facies.
Terrane occurs as a narrow fault-bounded lens along Broxson Gulch thrust
between Maclaren terrane to north and Wrangellia terrane to south.
Because of the assemblage of basalt and rhyolite volcanic rocks, and
shallow-water sedimentary rocks, Clearwater terrane interpreted as a
shallow-level fragment of an island arc. **REFERENCES**: Nokleberg and
others, 1985, 1989a, 1992; Csejtey and others, 1992

CZ **Crazy Mountains terrane (passive continental margin)Ñ**Occurs in
east-central Alaska in two displaced fragments and consists of two major
sequences: (1) maroon and green slate, and grit, and black limestone
with floating quartz grains with trace fossil *Oldhamia* of probable
Cambrian age in slate; and (2) younger sequence of Early Devonian or
older mafic volcanic rocks, agglomerate, chert, and clastic rocks,
fossiliferous Lower to Middle Devonian limestone, and Upper Devonian
chert-pebble conglomerate. Crazy Mountains terrane interpreted as a
displaced fragment of the early Paleozoic continental margin of North
America. **REFERENCES**: Churkin and others, 1982; Dover, 1990

DL **Dillinger terrane (passive continental margin)Ñ**Occurs as a major
unit in west-central Alaska, south of Denali fault, and in a smaller
fragment along branches of the fault. Within branches of fault, terrane
composed mainly of lower and middle Paleozoic carbonate and lesser
clastic rocks that consist of: (1) Cambrian and Ordovician basinal
limestone, banded mudstone, and silty limestone turbidites; and (2)
Upper Silurian through Middle Devonian, unnamed, shallow-water limestone
and dolomite. Structurally and (or) stratigraphically overlain by Mystic
terrane. Unconformably overlain by Upper Cretaceous Kuskokwim Group.
Stratigraphic column for area within branches of Denali fault. South of
Denali fault, terrane consists chiefly of: (1) Cambrian(?) to Ordovician
calcareous turbidite, shale, and minor greenstone; (2) Lower Ordovician
to Lower Silurian graptolitic black shale and chert; (3) Lower to Middle
Silurian laminated limestone and graptolitic black shale; (4) Middle to
Upper Silurian sandstone turbidites and shale; and (5) Upper Silurian to
Lower Devonian limestone, limestone, breccia, sandstone, and shale.
Dextrally offset along Denali fault in southwestern Alaska Range;
locally structurally and possibly stratigraphically overlain by Mystic
terrane. Complexly folded and faulted. Interpreted as lower to middle
Paleozoic, basinal facies equivalent to lower and middle Paleozoic rocks
of Nixon Fork terrane. Dillinger terrane interpreted by R.B. Blodgett,
T.K. Bundtzen, and J.B. Decker, Jr. (written commun., 1991), along with
Minchumina, Mystic, and Nixon Fork terranes, as part of the larger,
composite Farewell terrane. Dillinger terrane interpreted as a displaced
fragment of the Paleozoic and early Mesozoic continental margin of North
America. **REFERENCES**: Jones and others, 1982; Bundtzen and Gilbert,
1983; Gilbert and Bundtzen, 1984; Blodgett and Clough, 1985; R.B.
Blodgett, T.K. Bundtzen, and J.B. Decker, Jr., written commun., 1991

GD **Goodnews terrane (subduction zone - dominantly oceanic
rocks)Ñ**Occurs in southwestern Alaska and consists of a disrupted
assemblage of pillow basalt, diabase, gabbro, chert, argillite, minor
limestone, volcanogenic sandstone, and ultramafic rocks. Ordovician,
Devonian, Mississippian, Permian, and Triassic fossils in limestones.
Mississippian, Triassic, and Jurassic fossils in cherts. Metamorphic
grade of terrane ranges from prehnite-pumpellyite to greenschist to
blueschist facies. Blueschist facies minerals occur in two
geographically separated belts. Southern belt, south of Goodnews Bay,
intruded by pre-186 Ma diorite to gabbro plutons, yields Late Triassic
K-Ar blue amphibole age. Northern belt, near Kilbuck terrane, is
structurally adjacent to greenschist facies unit that yields Late
Jurassic K-Ar amphibole age. Goodnews terrane unconformably overlain by
Lower Cretaceous marine sandstone and conglomerate derived from Kilbuck
and Togiak terranes, and by Upper Cretaceous sedimentary rocks of
Kuskokwim Group, and intruded by Late Cretaceous and early Tertiary
plutonic rocks of Kuskokwim Mountains plutonic belt. Goodnews terrane
interpreted as subduction zone complex for the Togiak island arc
terrane. **REFERENCES**: Hoare and Coonrad, 1978; Murphy, 1987; Box,
1985a, b; Box and others, 1992; Dusel-Bacon and others, 1992; Patton and
others, 1992

KI **Kilbuck-Idono terrane (cratonal)Ñ**Occurs in two fault-bounded
fragments about 330 km apart in southwestern and west-central Alaska.
Chiefly metamorphosed diorite, tonalite, trondhjemite, and granite
orthogneiss, subordinate amphibolite, and minor metasedimentary rocks,
mainly quartz-mica schist, marble, and garnet amphibolite of the
informally named Kanektok metamorphic complex of Hoare and Coonrad
(1979). Metaplutonic rocks yield Early Proterozoic (2.06 to 2.07 Ga)
U-Pb zircon ages of emplacement. Nd-Sm isotopic analyses indicate 2.5 Ga
(Archean) crustal component. Terrane metamorphosed to amphibolite facies
with retrograde greenschist facies metamorphism, possibly in Late
Mesozoic. Southern fragment constitutes Kilbuck terrane of Box and
others (1990); northern fragment constitutes Idono Complex of Miller and
others (1991). Unconformably overlain by Upper Cretaceous sedimentary
rocks of Kuskokwim Group. Kilbuck-Idono terrane interpreted as
highly-displaced cratonal fragment; no known correlative cratonal rocks
in North America. Possibly displaced from North Asian craton.
**REFERENCES**: Hoare and Coonrad, 1978, 1979; Turner and others, 1983;
Box and others, 1990; Miller and others, 1991

KY **Koyukuk terrane (island arc)Ñ**Occurs in northern and southern
sequences within Yukon-Koyukuk basin in west-central Alaska. Northern
sequence, north of Kaltag fault, chiefly basalt, voluminous Lower
Cretaceous (Neocomian) andesite flows, tuff, breccia, conglomerate,
tuffaceous graywacke, mudstone, and bioclastic limestone. Fossil and
isotopic ages of Late Jurassic through Early Cretaceous (Berriassian to
Aptian). Southern sequence, south of Kaltag fault, consists of Middle
and Late Jurassic tonalite and trondhjemite plutonic rocks that intrude
Angayucham terrane basement of Koyukuk terrane. Upper Jurassic to Lower
Cretaceous volcanic and related rocks associated with, and unconformably
overlie tonalite-trondhjemite plutonic rocks and locally an older suite
of units, similar to Angayucham terrane, with microfossil ages that
range from Pennsylvanian to Triassic. Volcanic and plutonic rocks
constitute Middle Jurassic to Early Cretaceous Koyukuk arc. Terrane is
depositionally overlain by Lower Cretaceous marine sedimentary rocks of
Yukon-Koyukuk basin, and by volcanic rocks of Yukon-Kanuti igneous belt.
Terrane structurally underlain by Angayucham terrane. Koyukuk terrane
and nearby Nyac and Togiak terranes are interpreted as a group of
broadly coeval Jurassic and Early Cretaceous island arc terranes.
**REFERENCES**: Patton, 1973; Box and Patton, 1989; Patton and others,
1989; Patton, 1991

LG **Livengood terrane (oceanic crust)Ñ**Occurs in east-central Alaska
and consists of a structurally deformed and poorly-exposed assemblage
of: (1) serpentinized harzburgite, minor dunite, and Cambrian diabase,
gabbro, and diorite; (2) Ordovician ribbon chert with graptolitic shale
(Livengood Dome Chert); (3) undated (Silurian(?) to Late Proterozoic(?))
silicified dolomite with lesser chert, limestone, argillite, basalt, and
volcaniclastic rocks (Amy Creek and Lost Creek units); and (4) Late
Silurian limestone debris flows interbedded within siliciclastic strata;
and (5) unconformably overlying Middle Devonian turbidites composed of
conglomerate with clasts of mafic and ultramafic rocks, and sandstone
and mudstone with minor limestone. (Cascaden Ridge unit). Terrane occurs
as one of several, narrow, east-northeast trending terranes in region.
Faulted against Crazy Mountains, Ruby, and Angayucham terranes to
northwest. Thrust under Manley terrane to southeast. Livengood terrane
interpreted as a fragment of a Cambrian ophiolite and oceanic crust with
overlying Cambrian to Silurian pelagic and continental rise and slope
deposits, and Devonian turbidite deposits. **REFERENCES**: Churkin and
others, 1980; Weber and others, 1985; Jones and others, 1986; Loney and
Himmelberg, 1988; Dover, 1990; Grantz and others, 1991; Blodgett 1992;
Blodgett and others, 1988; Weber and others, 1992

MA **Manley terrane (turbidite basin)Ñ**Occurs in east-central Alaska as
three distinct flysch sequences: (1) Upper Triassic or Upper Jurassic
unfossiliferous, carbonaceous, slate, argillite, phyllite with sparse
chert- and quartzite-pebble conglomerate, and minor chert intruded by
gabbro (Vrain unit); (2) Upper Jurassic to Lower Cretaceous quartzite
and pebble conglomerate (Wolverine unit); and (3) Albian and Upper
Cretaceous shale, siltstone, graywacke, and polymictic conglomerate
(Wilber Creek unit) probably derived from a magmatic arc and from
sedimentary and volcanic rocks of White Mountains and Livengood
terranes. Intruded by mid-Cretaceous granitic rocks. Terrane
structurally overlies Livengood terrane and structurally overlain by
White Mountains terrane. Manley terrane interpreted as displaced
fragment of a Mesozoic overlap assemblage, possibly originally deposited
on Livengood terrane. Possible offset equivalent of Kandik River overlap
assemblage. **REFERENCES**: Jones and others, 1981, 1986; Weber and
others, 1985, 1988; Gergen and others, 1988; Dover, 1990; Grantz and
others, 1991

MK **McKinley terrane (sea mount)Ñ**Occurs between branches of Denali
fault in central Alaska Range and consists chiefly of a strongly folded
and faulted structural complex assemblage of: (1) fine-grained Permian
flysch, mainly graywacke, argillite, and minor chert; (2) Triassic
chert; (3) a thick sequence of Upper Triassic (Norian) pillow basalt;
(4) Upper Jurassic(?) to Cretaceous flysch, mainly graywacke, argillite,
minor conglomerate and chert; and (5) Late Jurassic(?) to Cretaceous
gabbro and diabase. Also included are Mississippian to Upper Triassic
chert (Red Paint subterrane) that is thrust over, and folded with the
upper Mesozoic flysch. McKinley terrane interpreted as a fragment upper
Paleozoic deep-sea sedimentary rocks and one or more Late Triassic
seamounts. One of several terranes in tectonic lenses along Denali
fault. **REFERENCES**: Jones and others, 1981, 1982, 1987; Gilbert and
others, 1984

ML **Maclaren terrane (continental margin arc)Ñ**Occurs in a narrow,
east-west-striking lens between the Denali fault and the Broxson Gulch
thrust in eastern Alaska Range. Consists of Maclaren Glacier metamorphic
belt to the south and East Susitna batholith to the north. Maclaren
Glacier metamorphic belt contains three fault-bounded sequences of: (1)
Upper Jurassic or older argillite, flysch, and sparse andesite and
marble; (2) phyllite and metagraywacke; and (3) pelitic schist and
amphibolite. Protolith for Maclaren Glacier metamorphic belt may be
older part of Kahiltna ovrlap assemblage. Progressively metamorphosed
from lower greenschist facies to upper amphibolite facies. Higher
metamorphic-grade units, adjacent to East Susitna batholith,
structurally overlie lower-grade units to south. East Susitna batholith
(unit TKpi) chiefly mid-Cretaceous to early Tertiary regionally
metamorphosed and penetratively deformed granitic plutonic rocks.
Maclaren terrane also includes Nenana terrane of Jones and others (1981,
1987). Maclaren terrane thrust over Wrangellia terrane to south and
interpreted as a offset fragment of Cretaceous continental-margin arc
formed in southeastern Alaska and southwestern Yukon Territory (Kluane
Schist and Ruby Range batholith). **REFERENCES**: Smith, 1981; Nokleberg
and others, 1985, 1989a, 1992; Csejtey and others, 1992; Davidson and
others, 1992

MN **Minchumina terrane (passive continental margin)Ñ**Occurs in central
Alaska and consists of a complexly folded assemblage of: (1) Cambrian(?)
limestone, dolomite, phyllite, and argillite; (2) Ordovician argillite,
quartzite, grit, and chert; (3) Ordovician chert, argillite, shaley
limestone, and siliceous siltstone; and (4) Middle to Upper Devonian
limestone and dolomite. Minchumina terrane interpreted by R.B. Blodgett,
T.K. Bundtzen, and J.B. Decker, Jr., written commun. (1991), along with
Mystic, and Nixon Fork terranes, as part of the composite Farewell
terrane. Minchumina terrane designated as separate terrane by Patton and
others (1989) and in this study, and interpreted as a sequence of
deep-water deposits that formed along a continental margin adjacent to
the lower Paleozoic platform carbonate rocks of the Nixon Fork terrane
to west. Both terranes interpreted as displaced fragments of the
Paleozoic and early Mesozoic continental margin of North American.
**REFERENCES**: Jones and others, 1981; Patton and others, 1989; R.B.
Blodgett, T.K. Bundtzen, and J.B. Decker, Jr., written commun., 1991

MNK **Minook terrane (turbidite basin)Ñ**Occurs in east-central Alaska
and consists chiefly of flysch composed conglomerate, sandstone,
siltstone, and shale. Conglomerate consists mainly of chert pebble and
lesser quartz, slate, and sandstone fragments in a sandy and locally
calcareous matrix. Shales contain rare thin argillaceous sandstone and
siltstone layers. Early Permian(?) megafossils. Moderately to intensely
folded and occurs as east-northeast-trending lens structurally adjacent
to Ruby, Livengood, and Manley terranes. Origin of Minook terrane
uncertain; may be a fragment of the Nixon Fork, Angayucham, or Tozitna
terranes. **REFERENCES**: Chapman and others, 1971; Jones and others,
1981; Dover, 1990; Grantz and others, 1991

MY **Mystic terrane (passive continental margin)Ñ**Occurs in central
Alaska, mainly south of Denali fault and consists of a complexly
deformed, but partly coherent, long-lived stratigraphic succession of:
(1) Ordovician graptolitic shale and associated(?) pillow basalt; (2)
Silurian massive limestone; (3) Upper Devonian sandstone, shale,
conglomerate, and limestone (informally-named Yentna limestone of
Fernette and Cleveland (1984)); (4) uppermost Devonian to Pennsylvanian
radiolarian chert; (5) Pennsylvanian siltstone, sandstone, and
conglomerate; (6) Pennsylvanian(?) and Permian flysch, chert, argillite,
and conglomerate (locally plant bearing); and (7) Triassic(?) pillow
basalt and gabbro. Terrane structurally and possibly locally
stratigraphically underlain by rocks of Dillinger terrane. Pre-Devonian
rocks assigned in part to Dillinger terrane (Gilbert and Bundtzen, 1984;
Blodgett and Gilbert, 1992). Mystic terrane interpreted by R.B.
Blodgett, T.K. Bundtzen, and J.B. Decker, Jr. (written commun., 1991),
along with Dillinger, Minchumina, and Nixon Fork terranes, as part of
the composite Farewell terrane. Mystic terrane interpreted as a
displaced fragment of the Paleozoic and early Mesozoic continental
margin of North America. **REFERENCES**: Reed and Nelson, 1980; Gilbert
and Bundtzen, 1984; Blodgett and Gilbert, 1992; R.B. Blodgett, T.K.
Bundtzen, and J.B. Decker, Jr., written commun., 1991

NX **Nixon Fork terrane (passive continental margin)Ñ**Occurs in several
fault-bounded fragments in central and west-central Alaska and consists
of a long-lived stratigraphic succession of: (1) Late Precambrian
basement of mainly pelitic and calcareous schists with minor marble,
quartzite, and felsic metavolcanic rocks; (2) overlying unmetamorphosed
sedimentary rocks consisting of dolograinstone and laminated
dolomudstone; (3) overlying unmetamorphosed sedimentary rocks of
probable Late Proterozoic age consisting of two units (interbedded
sandstone, siltstone, and carbonate), and two dolostone units (Babcock
and others, 1993); (4) Middle Cambrian limestone and chert; (5) Upper
Cambrian to Lower Ordovician platy limestone (possibly part lower part
of Novi Mountain Formation); (6) Lower Ordovician thick and platy
limestone (Novi Mountain Formation); (7) Ordovician to Middle Devonian
carbonate platform rocks (Telsitna, Paradise Fork, and Whirlwind Creek
Formations, and Cheeneetnuk Limestone (R.B. Blodgett, written commun.,
1993); and (7) Permian, Triassic, and Cretaceous fossiliferous
sedimentary rocks, mainly calcareous sandstone, siltstone, conglomerate,
and sparse chert. Proterozoic stratified rocks intruded by Middle
Proterozoic metagranitic rocks with U-Pb zircon age of 1.27 Ga, and
capped by Late Proterozoic metavolcanic rocks with U-Pb zircon age of
850 Ma. Middle Paleozoic strata grade laterally into deep-water strata
equivalent to Dillinger terrane. Permian strata contain clasts of
basement rocks.

Nixon Fork terrane is stratigraphically overlain by unnamed Triassic and
Lower Cretaceous clastic rocks and by Upper Cretaceous Kuskokwim Group,
and locally structurally overlain by Angayucham terrane. Nixon Fork
terrane interpreted by R.B. Blodgett, T.K. Bundtzen, and J.B. Decker,
Jr., written commun. (1991), along with Dillinger, Minchumina, and
Mystic terranes, as part of the larger, composite Farewell terrane.
Nixon Fork terrane is designated as separate terrane by Patton and
others (1989) and in this study; interpreted as one of several displaced
fragments of the Paleozoic and early Mesozoic continental margin of
North America. **REFERENCES**: Patton and others, 1980, 1989, Blodgett
and Gilbert, 1983; Blodgett and Clough, 1985; Clough and Blodgett, 1985;
Palmer and others, 1985; R.B. Blodgett, T.K. Bundtzen, and J.B. Decker,
Jr. written commun., 1991; Babcock and Blodgett, 1992

NY **Nyac terrane (island arc)Ñ**Occurs in southwest Alaska and consists
chiefly of andesite and basalt flows, breccia, tuff, and interbedded
shallow-marine volcaniclastic rocks with Middle and Late Jurassic
(Bajocian and Tithonian) fossils. Terrane intruded by Early Cretaceous
gabbroic and granitic rocks and depositionally overlain by Late
Cretaceous and early Tertiary volcanic rocks of the Kuskokwim Mountains
igneous belt. Nyac and nearby Koyukuk and Togiak terranes are
interpreted as a group of several broadly coeval Jurassic and Early
Cretaceous island arc terranes. **REFERENCES**: Hoare and Coonrad, 1978;
Box, 1985a, b; Box and others, 1992

PC **Porcupine terrane (passive continental margin)Ñ**Occurs in northern
east-central Alaska and consists of a long-lived stratigraphic
succession of: (1) Precambrian (Proterozoic?) phyllite, slate,
quartzite, marble, greenstone (metabasalt) rocks; (2) thick,
structurally and stratigraphically complex assemblage of Cambrian(?) to
Upper Devonian shallow-water limestone, dolomite, and minor chert minor
shale (including Salmontrout Limestone); (3) upper Paleozoic sandstone,
siltstone, argillite, massive quartzite, conglomerate, and minor
limestone; and (4) Permian Step Conglomerate. Jurassic ammonite-bearing
strata occur in two places in the northern part of the terrane. Terrane
thrust over Kandik River assemblage to southeast, locally overthrust by
Angayucham terrane, and depositionally overlain by now faulted Kandik
River assemblage. Porcupine terrane interpreted as a displaced fragment
of the Paleozoic and Mesozoic continental margin of North America.
**REFERENCES**: BrosgŽ and Reiser, 1969; Imlay and Detterman, 1973;
Howell and Wiley, 1987; Howell and others, 1992; Lane and Ormistron,
1979

PN **Pingston terrane (turbidite basin)Ñ**Occurs in discontinuous,
narrow, fault-bounded lenses along Denali fault in central Alaska Range.
Chiefly a weakly metamorphosed, strongly folded, and faulted sequence
of: (1) Early Pennsylvanian and Permian phyllite, minor marble, and
chert; (2) Upper Triassic thin-bedded, laminated dark limestone, black
sooty shale, calcareous siltstone, and minor quartzite; and (3) locally
numerous bodies of post-Late Triassic gabbro, diabase, and diorite.
Terrane contains a single slaty cleavage that parallels axial planes of
locally abundant isoclinal folds. Terrane also occurs in a small lens of
thin-bedded dark limestone, sooty shale, and minor quartzite in eastern
Alaska Range (W.J. Nokleberg and D.H. Richter, unpub. data, 1987). Most
widespread, Upper Triassic part of terrane interpreted as a
turbidite-apron sequence deposited from deep-water turbidity currents
that flowed from a cratonal source, such as the Yukon-Tanana terrane to
the north, onto upper Paleozoic continental slope-rise deposits.
**REFERENCES**: Jones and others, 1981, 1982; Gilbert and others, 1984

PW **Prince William terrane (accretionary wedge - dominantly
turbidites)Ñ**Occurs in southern Alaska and consists chiefly of a
complexly folded and faulted, thick assemblage of graywacke, argillite,
minor conglomerate, pillow basalt, and basaltic tuff, sills, and dikes,
and ultramafic rocks (Orca Group, Sitkalidak Formation, and Ghost Rocks
Formation). Includes Late Cretaceous and early Tertiary Ghost Rocks
terrane of Jones and others (1987). Rare mega- and microfossils of
Paleocene and Eocene age

Terrane bounded to north by Contact fault and Chugach terrane, to south
by Aleutian megathrust or late Cenozoic accretionary prism, and to east
by Yakutat terrane. In central and western parts of Prince William
Sound, large areas occur without fossil control on either side of
Contact fault that in this area may be a gradational accretionary zone.
Sandstone petrologic studies indicate local gradational contact between
Prince William and Chugach terranes (Dumoulin, 1987, 1988). In eastern
part of Prince William Sound, east of Valdez and Cordova, singly
deformed Orca Group of Prince William terrane is thrust under
doubly-deformed and metamorphosed rocks of Valdez Group of southern
Chugach terrane (Plafker and others, 1989b).

One early Tertiary granitic pluton of Sanak-Baranof plutonic belt (50-65
Ma) and local adjacent amphibolite facies metamorphism welds the
northern Prince William terrane to the southern Chugach terrane. Early
Tertiary zeolite to greenschist facies metamorphism. Local ophiolite
exposed on Resurrection Peninsula and on Knight Island; interpreted as
slabs of oceanic basement. Prince William terrane overlain by
assemblages of marine clastic rocks and local continental coal-bearing
rocks of post-middle Eocene age. Prince William terrane interpreted as
early Tertiary oceanic lithosphere, seamounts, and deep-sea fan
assemblage that was tectonically imbricated into an extensive
accretionary wedge complex. **REFERENCES**: Tysdal and Case (1979),
Moore and others, 1983; Nelson and others, 1985; Dumoulin, 1987, 1988;
Plafker and others, 1989b; Nelson, 1992

RB **Ruby terrane (metamorphosed continental margin)Ñ**Occurs in
northern west-central Alaska and consists chiefly of a structurally
complex assemblage of quartz-mica schist, quartzite, calcareous schist,
mafic greenschist (metabasalt), quartz-feldspar schist and gneiss, and
marble. Sparse Silurian and Devonian fossils occur in metasedimentary
rocks. Local granitic gneiss with Devonian and Early Cretaceous U-Pb
zircon age. Generally metamorphosed to greenschist facies and local
amphibolite faces, with sparse relict blueschist facies metamorphic
minerals. Ruby terrane is overthrust by Angayucham terrane, is
unconformably overlain by Lower Cretaceous sedimentary rocks of
Yukon-Koyukuk basin and by Upper Cretaceous Kuskokwim Group, and is
extensively intruded by mid-Cretaceous granitic plutons. Ruby terrane
interpreted as a highly metamorphosed and deformed, displaced fragment
of the North American craton margin. **REFERENCES**: Patton and others,
1987, 1989

SD **Seward terrane (metamorphosed continental margin)Ñ**Occurs on
Seward Peninsula in western Alaska and consists chiefly of a
structurally complex assemblage of mica schist, micaceous calc-schist,
metavolcanic rocks, and carbonate rocks. Consists of informally-named
Nome Group composed of pelitic schist, marble, quartz-graphite schist,
and mafic schist (rift-related metabasalt, calc-schist, and
chlorite-albite schist). Metasedimentary rocks contain Cambrian through
Silurian conodonts and megafossils. Part of terrane may be Proterozoic
in age. Associated carbonate rocks occur in poorly-exposed area in
eastern part of terrane and range in age from Lower Cambrian to Middle
Devonian. Regionally metamorphosed at blueschist facies, and retrograded
to greenschist facies. Penetratively deformed. Terrane includes a small
pluton (informally named Kiwalik Mountain orthogneiss of A.B. Till and
J.A. Dumoulin, written commun., 1991) that yields U-Pb zircon age of 381
Ma. Central part of terrane consists mainly of Kigluaik Group that
contains: (1) upper unit of pelitic and calcareous schist, marble, and
lesser amphibolite and quartz-graphite schist metamorphosed up to upper
amphibolite facies, and interpreted as a higher-grade counterpart of the
Nome Group; and (2) lower unit of marble gneiss, mixed gneiss, and
gneissic granitic rocks, metamorphosed up to granulite facies. Locally
intruded by large Cretaceous plutons. Correlated with Coldfoot terrane
to northeast. Seward terrane interpreted as a highly metamorphosed and
deformed, displaced fragment of the North American craton margin.
**REFERENCES**: Armstrong and others, 1986; Hudson, 1977; A.B. Till and
J.A. Dumoulin, written commun., 1991; Patton and others, 1992

SM **Seventymile terrane (subduction zone - dominantly oceanic
rocks)Ñ**Occurs in east-central Alaska as scattered remnants of three
highly-deformed and locally folded thrust sheets. Structurally overlies
Yukon-Tanana and Stikinia terranes.

Lower thrust sheet composed chiefly structural melange of undated
metasandstone, metagraywacke, and metaconglomerate, and metaandesite.
Pervasively metamorphosed to lower greenschist facies in Mesozoic time.
Lower thrust sheet interpreted as a fragment of an island arc.

Middle thrust sheet composed chiefly structural melange of pillow
basalt, basalt, mafic tuff, chert, argillite, and limestone. Cherts and
limestones contain Mississippian, Permian, and Late Triassic
radiolarians or conodonts. Locally, limestone contains assemblage of
giant *Parafusulina,* indicating tropical depositional environment (C.S.
Stevens, written commun. to D.G. Howell, 1990) that also occurs in
similar oceanic and (or) ophiolite terranes in the Canadian Cordillera,
Klamath Mountains, and northwest Mexico. Pervasively metamorphosed to
lower greenschist facies in Mesozoic time. Sparse relict glaucophane in
pillow basalt. Middle thrust sheep interpreted as subduction zone
melange of late Paleozoic and early Mesozoic oceanic crust and sea
mounts.

Upper thrust sheet composed chiefly harzburgite, peridotite, and minor
clinopyroxenite, and gabbro, and diabase with local amphibolite sole.
Upper thrust sheet interpreted as possible roots to a Jurassic(?) island
arc. Lower and middle thrust sheets pervasively metamorphosed to lower
greenschist facies in Mesozoic time. **REFERENCES**: Keith and others,
1981; Foster and others, 1987

ST(?) **Stikinia(?) terrane - east-central Alaska (island arc)Ñ-**Occurs
in eastern east-central Alaska and consists chiefly of metasedimentary
rocks intruded by large Late Triassic to Early Jurassic granitic plutons
of Taylor Mountain batholith. Metasedimentary rocks mainly
biotite-hornblende gneiss, marble, amphibolite, quartzite, pelitic
schist, quartz-feldspar schist, and metachert. Protoliths of
metasedimentary rocks interpreted as forming in an oceanic or marginal
basin. Stikinia(?) terrane intensely deformed. and metamorphosed to
amphibolite and epidote-amphibolite facies at high temperatures and
pressures, with local kyanite, during Early to Middle Jurassic.
Structurally overlies Yukon-Tanana terrane and is structurally overlain
by Seventymile terrane. Stikinia(?) terrane interpreted as part of an
extensive early Mesozoic oceanic igneous arc. **REFERENCES**: Foster and
others, 1987; Dusel-Bacon and Hansen, 1992

ST **Stikinia terrane - southeastern Alaska (island arc)Ñ**Occurs in
southern southeastern Alaska and consists of: (1) basal sequence
consists of Late Proterozoic(?), Devonian(?), Carboniferous, and Permian
andesitic, basaltic, and minor rhyolitic volcanic and volcaniclastic
rocks with interbedded marine limestone and clastic sedimentary rocks;
and (2) Upper Triassic to Upper Jurassic marine sedimentary clastic
rocks, minor limestone, and various volcanic rocks (Hazelton and Stuhini
Formations of Souther (1971) and Anderson (1989) that are locally
intruded by Late Triassic and Early Jurassic granitic rocks, and by
middle Tertiary intermediate plutonic rocks. Stikinia terrane is
interpreted as occurring structurally or stratigraphically above
Yukon-Tanana terrane. Stikinia terrane interpreted as part of an
extensive early Mesozoic oceanic igneous arc. **REFERENCES**: Monger and
Berg, 1987; Monger and others, 1982; Bevier and Anderson, 1991;
Evenchick, 1991

SU **Susitna terrane (sea mount)Ñ**Occurs in northern part of the
Talkeetna Mountains and consists of thick piles of pillow basalt,
deep-marine tuffaceous sedimentary rocks, sandstone, and tuff. Late
Triassic (Norian) *Monotis* *subcircularis* and *Heterastridium* sp.
locally abundant in argillite interbedded with volcanic rocks. Terrane
forms rootless nappe in highly-deformed Mesozoic flysch of the Kahiltna
overlap assemblage. The upper contact of basalt with flysch originally
may have been depositional, but relations now obscured by subsequent
shearing along the contact. Susitna terrane interpreted as possible
fragment of an oceanic seamount and (or) fragment of the Peninsular
terrane, possibly lithologically equivalent to the Cottonwood Bay or
Chilikadrotna Greenstones, that was tectonically decoupled from its
basement and faulted into the Kahiltna overlap assemblage of flysch
during the mid- or Late Cretaceous. **REFERENCES**: Jones and others,
1980, 1982

SW **Southern Wrangellia terrane (island arc)Ñ**Occurs in southern
Alaska along southern margin of Wrangellia terrane and consists mainly
of two sequences: (1). Older sequence composed of a fault-bounded
assemblage of generally highly-deformed and metamorphosed sedimentary
and volcanic rocks of late Paleozoic and older age (stratified part of
metamorphic complex of Gulkana River and Strelna Metamorphics of Plafker
and others (1989b)). Metasedimentary and metavolcanic rocks mainly
chlorite schist derived from andesite, metabasalt, metatuff,
calc-schist, pelitic schist, metachert, and marble that locally contains
Early Pennsylvanian conodonts. (2) Younger sequence composed of
metamorphosed and deformed late Paleozoic and Late Jurassic metaplutonic
rocks (plutonic part of metamorphic complex of Gulkana River and
Uranatina River metaplutonic unit and Chitina Valley batholith of
Plafker and others (1989b)). Paleozoic metaplutonic rocks, with U-Pb
ages of 308 to 312 Ma, consist of schistose hornblende diorite and
gabbro, metagranodiorite, metagranite, and orthogneiss. Late Jurassic
metaplutonic rocks, with an U-Pb zircon age of 153 Ma, consist mainly of
hornblende diorite and tonalite. Southern Wrangellia terrane generally
intensely deformed and regionally metamorphosed from greenschist facies
to amphibolite facies near metaplutonic rocks. Local mylonite zones
occur adjacent to, and within syntectonic Late Jurassic metaplutonic
rocks.

Southern Wrangellia terrane locally structurally overlain or underlain
by greenstone and Upper Triassic carbonate sequence inferred to be
equivalent of Upper Triassic strata that characterize the Nikolai
Greenstone, and Chitistone and Nizina Limestones of the Wrangellia
terrane. Late Paleozoic part of terrane interpreted as part of late
Paleozoic Skolai arc of Wrangellia terrane. Late Jurassic metaplutonic
rocks constitute part of Chitina arc. Southern Wrangellia terrane
locally occurs as moderate-size klippen thrust onto northern Chugach
terrane during mid-Cretaceous faulting along Border Ranges fault.
Southern Wrangellia terrane interpreted either as: (1) a deeper and more
metamorphosed equivalent of the Wrangellia terrane to the north; or (2)
as a distinct terrane structurally juxtaposed between the Wrangellia
terrane to north and Peninsular terrane to south. Equivalent to Strelna
terrane of Grantz and others (1991). **REFERENCES**: Plafker and others,
1989b; Nokleberg and others, 1989b; Grantz and others, 1991

TG **Togiak terrane (island arc)Ñ**Occurs in southwestern Alaska and
consists of two major sequences: (1) lower ophiolite sequence of Late
Triassic mid-ocean-ridge pillow basalt, diabase, gabbro, and ultramafic
rocks at southwestern end of unit; and (2) coherent upper stratigraphic
sequence of Lower Jurassic to Lower Cretaceous marine volcaniclastic
sandstone, conglomerate, shale, tuffaceous chert, and minor argillaceous
limestone, and marine to non-marine andesite and basalt flows and flow
breccia, and tuff. Depositionally overlain by Upper Cretaceous marine
sedimentary rocks of Kuskokwim Group, and by volcanic and plutonic rocks
of Kuskokwim Mountains igneous belt. Togiak terrane may depositionally
overly Tikchik terrane at northeastern end of unit. Togiak and nearby
Koyukuk and Nyac terranes interpreted as a group of broadly coeval
Jurassic and Early Cretaceous island arc terranes. **REFERENCES**: Hoare
and Coonrad, 1978; Box, 1985a, b; Box and others, 1992

TK **Tikchik terrane (island arc)Ñ**Occurs in southwestern Alaska as
structurally complex assemblage of andesite, dacite, and rhyolite
volcanic rocks, volcaniclastic rocks, chert, tuffaceous chert,
chert-clast sandstone, limestone, dolomite, and argillite that contain
microfossils of pre-Late Devonian, Devonian, Mississippian, Permian, and
Triassic age. Tikchik terrane depositionally overlain by Upper
Cretaceous marine sedimentary rocks of Kuskokwim Group, and intruded by
Late Cretaceous to early Tertiary plutonic rocks of Kuskokwim Mountains
igneous belt. Tikchik terrane interpreted as possible depositional
basement to Togiak (island arc) terrane. **REFERENCES**: Hoare and
Coonrad, 1978; Hoare and Jones, 1981; Box, 1985a, b; Box and others,
1992

UM **Ultramafic and associated rocks (oceanic crust?)Ñ**Occurs as
narrow, fault-bounded, near-vertical prisms and sparse klippen
discontinuously exposed for several hundred kilometers along the Denali
fault in the eastern and central Alaska Range. Ultramafic rocks
(Mesozoic?) mainly fine- to medium-grained pyroxenite and peridotite,
and fine-grained dunite and are largely altered to serpentinite and
highly sheared. Associated rocks are amphibolite, hornblende-plagioclase
gneiss, marble derived from calcareous sedimentary rocks, and weakly
metamorphosed hornblende gabbro, tonalite, and granite. Amphibolite and
gneiss enclose ultramafic rocks. Intense strong schistosity that
subparallels contacts and enclosing faults. Tonalite and granite intrude
ultramafic and associated rocks; form small elongate plutons with
moderate schistosity that subparallels contacts. Terrane of ultramafic
and associated rocks interpreted as crustal-suture belt composed of
fragments of either oceanic lithosphere, an island arc, or less likely
deep-level continental lithosphere. Terrane may be derived in part from
basement of terranes juxtaposed along the Denali fault. **REFERENCES**:
Richter, 1976; Nokleberg and others, 1985, 1989a, 1992; Csejtey and
others, 1992; Patton and others, 1992

WF **West Fork terrane (turbidite basin)Ñ**Occurs in central Alaska
Range and consists of two sequences: (1) Upper sequence of chert,
argillite, and sandstone ranging in age from Early to Late Jurassic; and
(2) lower sequence of crystal tuff and volcaniclastic sandstone and
argillite that contains an Early Jurassic sandy conglomerate. Terrane
occurs structurally below Chulitna terrane to west and is faulted
against Broad Pass terrane to east. One of several mini-terranes
enclosed in highly deformed flysch of the Kahiltna overlap assemblage.
West Fork terrane interpreted as fragment of a turbidite basin or
submarine fan formed adjacent to Jurassic volcanic arc. **REFERENCES**:
Jones and others, 1982; Csejtey and others, 1992

WM **White Mountains terrane (passive continental margin)Ñ**Occurs as
one of several narrow east-northeast trending terranes in east-central
Alaska and consists of three units: (1) Ordovician phyllite, slate,
chert, and limestone overlain by pillow basalt, basaltic aquagene tuff,
and mafic volcanic breccia (Fossil Creek Volcanics) with local
volcaniclastic conglomerate containing granitic clasts dated at 560 Ma;
(2) Silurian limestone and dolomite (Tolovana Limestone); and (3)
undated gray, vitreous quartzite with argillite layers and Mississippian
diorite and gabbro sills (Globe quartzite unit of Weber and others
(1992)). Terrane moderately to intensely-deformed into
east-northeast-trending upright folds and parallel high-angle faults and
is similar to upper part of Crazy Mountains terrane to north across
Tintina fault. White Mountains terrane structurally overlies Manley
terrane to northwest and structurally underlies Wickersham terrane to
southeast. White Mountains terrane interpreted as displaced fragment of
the early Paleozoic continental margin of North America Cordillera.
**REFERENCES**: Churkin and others, 1982; Weber and others, 1985, 1988;
Dover, 1990; Aleinikoff and Plafker, 1989; Grantz and others, 1991

**Wrangellia superterrane (island arc)Ñ**Consists of middle Paleozoic
and older Alexander sequence, late Paleozoic and early Mesozoic
Wrangellia sequence, and Jurassic Peninsular sequence. Overlain by
younger late Mesozoic and Cenozoic sedimentary and volcanic rock
assemblages. Equivalent to combined Alexander, Peninsular, and
Wrangellia terranes of Jones and others (1987) and Monger and others
(1987). Corresponds to Wrangellia composite terrane of Plafker and
others (1989b) and Nokleberg and others (in press). Alexander and
Wrangellia sequences occur throughout southern and southeastern Alaska.
Peninsular sequence occurs mainly on Alaska Peninsula and adjacent areas
to northeast. Chief differences between regions underlain by
superterrane are notable contrasts in the relative abundances of coeval
strata. From east to west, the Alexander, Wrangellia, and Peninsular
sequences form successively higher levels of a structural-stratigraphic
succession. The dominantly early and middle Paleozoic Alexander
sequence, the oldest part of the succession, occurs mainly to the east
and southeast in southeastern Alaska; the late Paleozoic and early
Mesozoic Wrangellia sequence, the middle part of the succession, occurs
mainly to the north and west in southern Alaska; and the middle Mesozoic
Peninsular sequence, the youngest part of the succession occurs mainly
to the west on the Alaska Peninsula.

Substantial tectonic shortening occurs within the Wrangellia
superterrane (Plafker and others, 1989b; Nokleberg and others, in
press). The faulted juxtaposition of the Jurassic Talkeetna of the
Peninsular sequence in eastern-southern Alaska against the Wrangellia
sequence in the Wrangell Mountains requires extensive post-Middle
Jurassic tectonic displacement of this part of the Peninsular sequence
relative to the Wrangellia sequence. This post-Jurassic displacement
resulted in juxtaposition of different facies and, therefore, in the
original designation of the Peninsular and Wrangellia terranes as
separate units.

WRA **Alexander sequence (island arc)** (**southeastern Alaska)Ñ**Occurs
along length of southeastern Alaska and consists of Late Proterozoic to
middle Paleozoic volcaniclastic turbidites, siliceous shale, chert,
limestone, intermediate to mafic volcanic rocks, local polymictic
conglomerate, and early to middle Paleozoic plutonic rocks that are
overlain by late Paleozoic and early Mesozoic units of the Wrangellia
sequence, and by younger overlap assemblages. Age of exposed units
varies from north to south.

In the southern part of southeastern Alaska, late Proterozoic and Early
Cambrian Wales Group consists of metamorphosed volcanic, turbidite, and
carbonate rocks that are overlain by Ordovician through Mississippian,
interlayered volcaniclastic turbidites, carbonate rocks, and volcanic
rocks, shallow-water clastic and carbonate rocks, and sparse volcanic
rocks. These lithologies occur in the Port Refugio and Karheen
Formations, Heceta Limestone, and Descon Formations. In the northern
part of southeastern Alaska, the equivalent units, as depicted on
stratigraphic column, equivalent units are the Ordovician through
Devonian Gambier Bay, Freshwater Bay, and Cedar Cove Formations, Kennel
Creek Limestone, and Bay of Pillars, Point Augusta, Hood Bay, Cannery,
Saginaw Bay, and Iyoukeen Formations.

Alexander sequence includes abundant early to middle Paleozoic granitic
to gabbroic, and minor ultramafic plutons. In southeastern Alaska, the
Alexander sequence and overlying Wrangellia sequence are locally
overlain by parts of Gravina-Nutzotin overlap assemblage, including
Douglas Island Volcanics and Brothers Volcanics, and Seymour Canal and
Gravina Island Formations that are intruded by coeval plutonic rocks of
the Muir-Chichagof belt and Gravina arc. Locally unconformably overlain
by Tertiary and Quaternary basalt, dacite, rhyolite, sandstone, and
minor conglomerate.

In southeastern Alaska, Alexander sequence (and overlying Wrangellia
sequence) faulted against Chugach terrane to west and against Behm Canal
terrane to east. Alexander terrane interpreted as a displaced fragment
of an early through mid Paleozoic island arc. **REFERENCES**: Loney and
others, 1975; Turner and others, 1977; Eberlein and others, 1983; Brew
and others, 1984; Gehrels and Saleeby, 1986, 1987; Gehrels and others,
1987; Monger and Berg, 1987; Berg and others, 1988; Brew and others,
1991; Gehrels, 1990, 1991; McClelland and Gehrels, 1992; McClelland and
others, 1991; D.A. Brew, written commun., 1991

WRA **Alexander sequence - (island arc) (southern Alaska)Ñ**Occurs in
eastern Wrangell Mountains, eastern Alaska Range, and northern part of
Chugach Mountains. In Wrangell Mountains consists chiefly of early to
middle Paleozoic Kaskawulsh metamorphic rocks of Gardner and others
(1988), which are equivalent to the Kaskawulsh Group in adjacent parts
of Canada (Figure 3) (MacKevett, 1978; Campbell and Dodds, 1982a, b;
Gardner and others, 1988). Kaskawulsh metamorphic rocks are mainly a
highly deformed sequence of early Paleozoic marble, greenstone,
metagreywacke, phyllite, slate, schist, argillite, siltstone, mafic
volcanic rocks, and volcaniclastic rocks that are about a few thousand
meters thick. Multiply folded and strongly schistose. Metamorphosed from
upper greenschist to amphibolite facies. Devonian and older megafossils
occur widely in unit in Alaska and in the Yukon Territory to the east.
Intruded by Middle Pennsylvanian Bernard Creek pluton composed of
granite, syenite, and alkali granite, and by Jurassic and Cretaceous
tonalite and granodiorite of Chitina and Chisana arcs. Intrusion of the
Middle Pennsylvanian Bernard Creek pluton into both Alexander and
Wrangellia sequences indicates either stratigraphic continuity or
structural juxtaposition by about the Early Pennsylvanian.

In the eastern Alaska Range in eastern-southern Alaska, Alexander
sequence is interpreted to consist of pre-Pennsylvanian units of mica
and quartz schist, and relatively younger metagranitic rocks occur as
roof pendants in Pennsylvanian granitic rocks that also intrude upper
Paleozoic volcanic and related rocks (Nokleberg and others, in press).
In northern Chugach Mountains, north of the Border Ranges fault, the
Alexander sequence is interpreted to consist of sparse roof pendants of
quartz and pelitic schist, and marble (Knik River terrane) that occur
in, or are faulted against the adjacent Border Ranges ultramafic-mafic
assemblage of the Peninsular sequence, described below (Plafker and
others, 1989b; Nokleberg and others, in press). Alexander sequence in
southern Alaska interpreted as a displaced fragment of an early and
middle Paleozoic island arc. **REFERENCES**: MacKevett, 1978; Campbell
and Dodds, 1982a, b; Gardner and others, 1988; Plafker and others,
1989b; Nokleberg and others, in press

WRP **Peninsular sequence (island arc) (southern Alaska)Ñ**Occurs mainly
on Alaska Peninsula and adjacent area to northeast, and Kachemak Bay
area of the Kenai Peninsula. Consists mainly of an areal extensive
Jurassic island arc volcanic and plutonic sequence (Talkeetna arc) and
strata. Volcanic and plutonic sequence consists mainly of: (1) Upper
Triassic (Norian) and Lower Jurassic andesitic flows, breccias, and
volcaniclastic siltstone and sandstone (Talkeetna Formation) (volcanic
part of Talkeetna arc); (2) Jurassic batholithic granitic rocks
(plutonic part of Talkeetna arc); and (3) Middle Jurassic to Cretaceous
arc-derived clastic rocks (Shelikof and Chinitna Formations, Tuxedni
Group, Kialagvik Formation, Naknek Formation, Staniukovich and Herendeen
Formations), and bioclastic limestone (Nelchina Limestone).
Unconformably overlying units are Cretaceous to lower Tertiary,
progradational marine and non-marine sandstone, shale, and minor
conglomerate (Matanuska, Hoodoo, Chignik, and Kaguyak Formations).

Southern part of Peninsular sequence, adjacent to Denali fault, consists
of Early Jurassic Border Ranges ultramafic-mafic assemblage (BRUMA)
interpreted as roots of Talkeetna arc (Plafker and others, 1989b;
Nokleberg and others, in press). Peninsular sequence probably originally
overlain by Kahiltna assemblage along southern part of northwestern
margin, but is thrust over Kahiltna overlap along Talkeetna thrust.
Peninsular sequence is bounded to southeast by Border Ranges fault and
Chugach terrane, and is locally extensively overlain by Cenozoic
volcanic rocks of Aleutian arc. Peninsular sequence interpreted mainly
as a Upper Triassic and Jurassic oceanic island arc. **REFERENCES**:
Jones and others, 1981; Pavlis, 1983; Burns, 1985; Plafker and others,
1989b; Detterman and others, in press; Wilson and others, in press

WRW **Wrangellia sequence (island arc) (Southern and southeastern
Alaska)Ñ**Occurs mainly in southern and southeastern Alaska and is
inferred to occur to a minor extent in Puale Bay region of Alaska
Peninsula. Consists of late Paleozoic and Mesozoic sedimentary,
volcanic, and plutonic rocks. In southern Alaska, Wrangellia sequence
consists of: (1) Pennsylvanian and Permian island-arc-related volcanic
breccias, flows, and volcaniclastic rocks, mainly andesite and dacite,
and associated marine sedimentary rocks (Tetelna Volcanics, and Station
Creek and Slana Spur Formations). (2) Permian limestone, pelitic rocks,
and chert (Hasen Creek and Eagle Creek Formations). (3) Triassic
(Ladinian) black cherty argillite. (4) A thick section of Upper Triassic
(Norian) subaerial and marine tholeiitic pillow basalt and lesser
argillite (Nikolai Greenstone, up to thousand meters thick). (5) Upper
(Norian) Triassic platform and basinal limestone (Chitistone and Nizina
Limestones); and (6) Late Triassic and Jurassic basinal, siliceous,
argillaceous and calcareous rocks (McCarthy Formation). On northern
flank of Wrangell Mountains, unconformably overlying, Upper Jurassic and
Lower Cretaceous flysch and andesite volcanic rocks (Gravina-Nutzotin
overlap assemblage and Chisana Formation) form part of a major
tectonically-collapsed flysch basin that is intruded by coeval granitic
plutons. On southern flank of Wrangell Mountains, unconformably
overlying, mainly Middle Jurassic to Maastrichtian progradational,
volcaniclastic sequences (Root Glacier, Nizina Mountain, Chititu,
Moonshine Creek, Schulze, and Kennicott Formations). Overlain by Upper
Cenozoic to Holocene volcanic rocks (Wrangell Lava).

Upper Paleozoic sedimentary and volcanic rocks in Wrangellia sequence in
eastern-southern Alaska are intruded by coeval metaplutonic rocks of the
Skolai island arc. Late Triassic basalt and older rocks are intruded by
mafic and ultramafic dikes, sills, and small plutons. Late Triassic
basalts and associated plutonic rocks interpreted as products of rifting
and (or) oceanic plume activity. Wrangellia sequence locally intruded by
extensive Late Jurassic and Early Cretaceous granitic plutons of the
Chisana, Chitina, and Glacier Bay-Chichagof arcs. Pervasive weak
greenschist facies metamorphism in Early Cretaceous and older rocks. In
eastern Wrangell Mountains, Wrangellia sequence welded to northern
Alexander sequence by Middle Pennsylvanian granitic plutons of Skolai
arc. In southern Alaska, Wrangellia sequence faulted against
Yukon-Tanana and Maclaren terranes to north along Denali fault and
Broxson Gulch thrust, and to south faulted against southern Wrangellia
terrane along Chitina Valley and Paxson Lake faults.

On Alaska Peninsula, Wrangellia sequence consists of upper Paleozoic and
lower Mesozoic island arc and oceanic sequences that occur in Puale Bay
area and areas to north. Major units are: (1) Pennsylvanian(?) andesite
flows and agglomerate; (2) Permian limestone; and (3) Upper Triassic
(Norian) basalt, mafic tuff, limestone, and argillite (Kamishak
Formation), and correlative units of Cottonwood Bay and Chilikadrotna
Greenstones, and informally-named Tlikalika complex of Wallace (1983).

In southeastern Alaska, Wrangellia sequence consists of: (1) late
Paleozoic clastic and carbonate rocks; and (2) Late Triassic mafic and
lesser siliceous volcanic rocks. Major units are Mississippian,
Pennsylvanian, and Early Permian clastic, volcaniclastic, and carbonate
rocks of Cannery, Pybus, Ladrones Limestone, and Saginaw Bay, and Klawak
Formations, and Late Triassic mafic and lesser siliceous volcanic, and
carbonate rocks including the Hyd Group, Keku Volcanics, Goondip
Greenstone, Retreat Group (Duttweiler-Kelly, 1990), White Stripe Marble,
Chapin Peak Formation, and an unnamed sequence on the Chilkat Peninsula.
Overlying Upper Jurassic and Lower Cretaceous flysch of Gravina-Nutzotin
overlap assemblage. **REFERENCES**: Richter and others, 1975; Richter,
1976; Jones and others, 1977; MacKevett, 1978; Silberling and others,
1981; Johnson and Karl, 1985; Nokleberg and others, 1985, 1992, in
press; Gardner and others, 1988; and Plafker and others, 1989a, b;
Barker and others, 1989; Richards and others, 1991

WS **Wickersham terrane (passive continental margin)Ñ**Occurs as one of
several narrow east-northeast-trending terranes in east-central Alaska
and consists of turbidites comprising two major lithofacies: (1) a
structurally lower unit of mainly gray, maroon, and green slate with
local quartzose sandstone and granule to pebble conglomerate, with
dolomite and dark limestone; (2) an upper unit of mainly thick-bedded
quartzose sandstone and pebble conglomerate with local layers of gray
slate with local *Oldhamia* trace fossils of probable Cambrian age.
Former Beaver terrane of Churkin and others (1982). Southern margin of
Wickersham terrane exhibits penetrative metamorphic fabric and lower
greenschist metamorphism that parallels fault bounding southern margin.
Singly deformed and weakly metamorphosed. Structurally overlies White
Mountains terrane to northwest and Fairbanks schist unit of Nokleberg
and others (1989a) of Yukon-Tanana terrane to southeast. Wickersham
terrane interpreted as displaced fragment of the early Paleozoic
continental margin of North America Cordillera. **REFERENCES**: Churkin
and others, 1982; Weber and others, 1985, 1988; Pessel and others, 1987;
Moore and Nokleberg, 1988; Dover, 1990; Grantz and others, 1992

WY **Windy terrane (metamorphic)Ñ**Occurs as narrow, discontinuous
lenses along Denali fault in central and eastern Alaska Range and
consists of a structural melange of: (1) small to large fault-bounded
lenses of Silurian or Devonian limestone and marl; (2) Upper Triassic
limestone; (3) Jurassic(?) basalt and chert; (4) Cretaceous flysch and
volcanic rocks, mainly argillite, quartz-pebble siltstone, quartz
sandstone, metagraywacke, and metaconglomerate with lesser andesite and
dacite; and (5) Cretaceous(?) gabbro and diabase dikes and sills. Flysch
contains sparse Cretaceous ammonites. Intensely faulted and sheared with
a weak to intense schistosity formed at lower greenschist facies; local
phyllonite and protomylonite. Minimum structural thickness of a few
thousand meters. Windy terrane interpreted as a structural melange
formed during tectonic mixing during Cenozoic dextral-slip movement
along the Denali fault. Mesozoic flysch and associated volcanic rocks
interpreted as tectonic remnants of the Kahiltna overlap assemblage and
Chisana arc. Fragments of Silurian(?) and Devonian limestone and marl
may be derived from Dillinger, Mystic, and (or) Nixon Fork terranes.
**REFERENCES**: Jones and others, 1981; Nokleberg and others, 1985,
1989a, 1992; Stanley and others, 1990; Csejtey and others, 1992

YA **Yakutat terrane (accretionary wedge - dominantly
turbidites)Ñ**Occurs in southern Alaska and northern margin of Gulf of
Alaska and consists of an allochthonous composite terrane. Mesozoic
Yakutat Group forms eastern part, and Eocene oceanic crust forms western
part. Both eastern and western parts overlain by younger Cenozoic
sedimentary and volcanic rocks. Yakutat Group divided into: (1) melange
facies, chiefly basalt, chert, argillite, tuff, and sandstone of Late
Jurassic(?) and Early Cretaceous age, with exotic blocks of Permian and
Upper Triassic carbonate rocks, and Middle and Late Jurassic tonalite;
and (2) flysch facies, chiefly Upper Cretaceous volcanic sandstone,
siltstone, and minor conglomerate with structurally interleaved lenses
of disrupted chert, argillite, and volcanic rocks. Yakutat Group
metamorphosed from zeolite to lower greenschist facies and intruded by
Eocene granitoid plutons. Cenozoic sedimentary and volcanic rocks
divided into: (1) Lower and middle Tertiary oceanic basalt, sandstone,
siltstone, shale, and conglomerate (Poul Creek, Redwood, Kulthieth, and
Tokun Formations) that includes Eocene basalt and shale rich in organic
material; and (2) an overlap assemblage of Miocene and younger, shallow
marine sandstone, siltstone, diamictite, and conglomerate (Yakataga and
Redwood Formations). Terrane thrust under Prince William terrane to
north along gently north-dipping Chugach-Saint Elias fault, and to west
along subhorizontal Kayak Island fault zone; underthrust by Pacific
plate to south along Transition fault. Yakutat terrane interpreted as a
fragment of Chugach terrane (Yakutat Group) and Eocene oceanic crust
that, together with overlying pre-Miocene sequence, was displaced at
least 600 km northward along the Fairweather transform fault since the
early Miocene. **REFERENCES**: Jones and others, 1981; Plafker, 1987

YO **York terrane (passive continental margin)Ñ**Occurs on western
margin of Seward Peninsula and consists of a weakly metamorphosed,
structurally complex assemblage of Ordovician through Mississippian
limestone, argillaceous limestone, dolostone, and fine-grained clastic
rocks deposited in shallow-marine environment. Ordovician carbonate
rocks comprise most of unit and may range up to 3,000 m thick. Late
Proterozoic rocks may also occur. Terrane intruded by small, Late
Cretaceous granitic stocks, and may correlate with passive continental
margin rocks of Hammond terrane to northwest. York terrane interpreted
as a displaced fragment of the Paleozoic and early Mesozoic Arctic
continental margin.

**REFERENCES**: Sainsbury, 1969; Hudson, 1977; A.B. Till and J.A.
Dumoulin, written commun., 1991

YP **Yukon-Prong terrane (metamorphosed continental margin)
(southeastern Alaska)Ñ** Occurs in eastern southeastern Alaska and
consists chiefly of Late Proterozoic(?) and (or) early and middle
Paleozoic mica schist, granitic orthogneiss, amphibolite, metavolcanic
rocks, quartzite, marble, and calc-silicate rocks. Protoliths are
quartz-rich and pelitic sedimentary rocks, carbonate rocks, intermediate
to mafic volcanic rocks, ultramafic rocks, and sparse metamorphosed
middle Paleozoic granitic plutons. Terrane includes lower Paleozoic
metasedimentary rocks of Nisling assemblage (marble, metamorphosed
quartz sandstone, pelitic schist, and metabasalt), middle Paleozoic
metasedimentary and metavolcanic rocks of Ruth assemblage and Kah Shakes
sequence (pelitic schist, marble, mafic and felsic metavolcanic rocks,
metagranodiorite and orthogneiss) (former Tracy Arm terrane), and the
informally named Paleozoic East Behm gneiss complex of metaplutonic
rocks of Saleeby and Rubin (1990). Metamorphosed stratified and plutonic
rocks correlated with Yukon-Tanana terrane in east-central Alaska.
Metamorphosed before Late Triassic to amphibolite-facies

Yukon Prong terrane intruded by Late Cretaceous and Early Tertiary
intermediate plutonic rocks, and middle Tertiary intermediate plutonic
rocks. Bounded to west by structural complex of Behm Canal terrane.
Possibly stratigraphically(?) or structurally overlain by Stikinia
terrane. Interpreted as a highly metamorphosed and deformed, displaced
fragment of the North American craton margin. **REFERENCES**: Gehrels
and others, 1990; Saleeby and Rubin, 1990; Rubin and Saleeby, 1991;
McClelland and others, 1991, 1992; Samson and others, 1991; Gehrels and
McClelland, 1992

YT **Yukon-Tanana terrane (metamorphosed continental margin)
(east-central Alaska)Ñ**Occurs in eastern Alaska and adjoining Yukon
Territory of northwestern Canada and consists of an enormous tract of
poly-deformed and poly-metamorphosed, middle Paleozoic and older
sedimentary, volcanic, and plutonic rocks. Contains three major
sequences of metasedimentary, metavolcanic, and metaplutonic rocks that
occur in various subhorizontal to gently folded thrust slices. Major
sequences are: (1) Mississippian, Devonian, and locally older
metasedimentary rocks, mainly pelitic schist, quartz schist,
quartz-feldspar schist, and sparse marble (Fairbanks, Birch Hill, and
Chena River subterranes, and metasedimentary parts of Jarvis Creek
Glacier, Hayes Glacier, Lake George, and Macomb subterranes; Totatlanika
Schist, and Keevey Peak Formation); (2) Devonian and Mississippian
orthogneiss and augen gneiss (metaplutonic part of Lake George and
Macomb subterranes); and (3) Devonian and Mississippian intermediate and
siliceous metavolcanic rocks (Butte subterrane, metavolcanic rock parts
of Jarvis Creek, Hayes Glacier, and Lake George subterranes; Cleary
sequence within Fairbanks schist unit; and Spruce Creek sequence in the
Kantishna Hills area). The extrusive metavolcanic rocks and coeval
metamorphosed hypabyssal igneous rocks, mainly metamorphosed andesite,
dacite, and keratophyre flows and tuffs, are interlayered with the
Mississippian, Devonian, and locally older metasedimentary rocks.

U-Pbigneous isotopic analyses indicate Devonian and Mississippian
extrusion of intermediate and siliceous metavolcanic rocks (Cleary
sequence of Fairbanks subterrane, and Spruce Creek sequence) (Aleinikoff
and Nokleberg, 1989; Nokleberg and others, 1989a; J.N. Aleinikoff, T.K.
Bundtzen, and W.J. Nokleberg, unpub. data, 1993). Conodont and
megafossil ages indicate Mississippian and Devonian ages for
metasedimentary rock part of Jarvis Creek Glacier subterrane, and
Totatlanika Schist. One known Late Proterozoic metagranitic pluton
intrudes metasedimentary rocks in northern part of Chena River
subterrane (Nokleberg and others, 1989a), indicating at least part of
metasedimentary rocks are pre-Late Proterozoic in age. Locally near
Denali fault are abundant Cretaceous(?) metadiabase and metagabbro
dikes, sills, and small plutons.

Yukon-Tanana terrane contains an intense subhorizontal to gently dipping
structural fabric defined by parallel schistosity and composition
layering that are subparallel to major subhorizontal faults that
separate major thrust slices. Faults between major thrust slices exhibit
both older, early Mesozoic thrust, and younger, mid-Cretaceous
extensional displacements. Higher-grade units, with abundant Devonian
and Mississippian orthogneiss and augen gneiss, and upper amphibolite to
eclogite facies metamorphism, generally occur in deeper structural
levels. Lower-grade units, with abundant Devonian and Mississippian
volcanic rocks and upper greenschist facies metamorphism, generally
occur in higher structural levels. Intense zone of retrogressive
metamorphism and mylonitic schists along southern margin of terrane.
Major periods of amphibolite to eclogite facies metamorphism in Early
Jurassic and mid-Cretaceous time.

Southern margin of Yukon-Tanana terrane faulted against mainly Windy and
Wrangellia terranes. Northwestern margin thrust under Wickersham
terrane. Southern part of terrane interpreted as structurally underlain
in part by Mesozoic flysch of Kahiltna overlap assemblage. Northeastern
margin faulted North America craton margin, Kandik River, Angayucham,
and Crazy Mountains terranes along Tintina fault. Yukon-Tanana terrane
locally structurally overlain by formerly extensive klippen of
Seventymile and Stikinia(?) terranes in east-central Alaska. In same
area, locally unconformably overlain by Upper Cretaceous and lower
Tertiary conglomerate, sandstone, coal, and rhyolite to basalt tuff and
flows, and intruded by extensive mid-Cretaceous, Late Cretaceous, and
early Tertiary granitic plutons. Yukon-Tanana terrane interpreted as a
highly metamorphosed and deformed, displaced fragment of the North
American craton margin. Former Yukon Crystalline terrane of Churkin and
others, 1982. **REFERENCES**: Foster, 1976; Foster and others, 1987;
Nokleberg and others, 1989a, 1992; Stanley and others, 1990;
Dusel-Bacon, 1991; Pavlis and others, 1993; Dusel-Bacon and Hansen, 1992

**REFERENCES CITED**

Aleinikoff, J.N., Dusel-Bacon, Cynthia, Foster, H.L., and Nokleberg,
W.J., 1987, Pb-isotope fingerprinting of tectonostratigraphic terranes,
east-central Alaska: Canadian Journal of Earth Sciences, v. 24, p.
2089-2098.

Aleinikoff, J.N., and Nokleberg, W.J., 1989, Age of deposition and
provenance of the Cleary sequence of the Fairbanks schist unit,
Yukon-Tanana terrane, east-central Alaska, *in* Dover, J.H., and
Galloway, J.P., eds., Geologic studies in Alaska by the U.S. Geological
Survey, 1988: U.S. Geological Survey Bulletin 1903, p. 75-83.

Aleinikoff, J.N., and Plafker, George, 1989, In search of the provenance
and paleogeographic location of the White Mountains terrane: Evidence
from U-Pb data of granite boulders in the Fossil Creek Volcanics, *in*
Dover, J.H., and Galloway, J.P., eds., Geologic Studies in Alaska by the
U.S. Geological Survey, 1988: U.S. Geological Survey Bulletin 1903, p.
68-74.

Anderson, R.G.,1989, A stratigraphic, plutonic, and structural framework
for the Iskut River map area, northwestern British Columbia, *in*
Current Research, Part E, Geological Survey of Canada Paper 89-1E, p.
145-154.

Armstrong, R.L., Harakal, J.E., Forbes, R.B., Evans, B.W., and Thurston,
S.P., 1986, Rb-Sr and K-Ar study of metamorphic rocks of the Seward
Peninsula and southern Brooks Range, *in* Evans, B.W., and Brown, E.H.,
eds., Blueschists and Eclogites: Geological Society of America Memoir
164, p. 185-203.

Atwater, Tanya, and Severinghaus, Jeff, 1991, Tectonic map of the
north-central Pacific Ocean, in Winterer, E.L., Jussong, D.M., and
Decker, R.W., eds., The eastern Pacific Ocean and Hawaii: Geological
Society of America, Decade of North America Geology (DNAG), v. N, plate
3.

Babcock, L.E., and Blodgett, R.B., 1992, Biogeographic and
paleogeographic significance of Middle Cambrian trilobites of Siberian
Aspect from southwestern Alaska \[abs.\]: Geological Society of America
Abstracts with Programs, p. 4.

Babcock, L.E., Blodgett, R.B., and St. John, James, 1993, Proterozoic
and Cambrian stratigraphy and paleontology of the Nixon Fork terrane:
Proceedings of Circum-Pacific and Circum-Atlantic Terrane Conference,
Guanajuato, Mexico, p. 5-7.

Barker, F., 1987, Cretaceous Chisana island arc of Wrangellia, eastern
Alaska: Geological Society of America, Abstracts with Programs, v. 19,
no. 7, p. 580.

Barker, Fred, Jones, D.L., Budahn, J.R., and Coney, P.J., 1988, Ocean
plateau-seamount origin of basaltic rocks, Angayucham terrane, central
Alaska: Journal of Geology, v. 96, p. 368-374.

Barker, Fred, Sutherland Brown, A., Budahn, J.R., and Plafker, G., 1989,
Back-arc with frontal arc component origin of Triassic Karmutsen basalt,
British Columbia, Canada: Chemical Geology, v. 75, p. 81-102.

Beikman, H.M., 1980, Geologic map of Alaska: U.S. Geological Survey,
scale 1:2,500,000.

Berg, H.C., Elliott, R.L., and Koch, 1988, Geologic map of the Ketchikan
and Prince Rupert quadrangles, southeastern Alaska: U.S. Geological
Survey Map-1807, 2 sheets, 27 p.

Berg, H.C., Jones, D.L., and Richter, D.H., 1972, Gravina-Nutzotin
beltÑTectonic 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.

Bevier, M.L., and Anderson, R.G., 1991, Jurassic geochronometry in NW
Stikina (56-57¡N), British Columbia \[abs.\]: Geological Society of
America, Abstracts with Programs, v.23, no. 5, p. A191.

Bird, K.J., 1985, The framework geology of the North Slope of Alaska as
related to oil-source rock correlations, *in* Magoon, L.B., and
Claypool, G.E., eds., Alaskan North Slope oil/rock correlation
study:American Association of Petroleum Geologists Studies in Geology,
no. 20, p. 3-29.

Ñ1988, Alaskan North Slope stratigraphic nomenclature and data summary
for government-drilled wells: U.S. Geological Survey Professional Paper
1399, p. 317-353.

Bird, K.J., and Molenaar, C.M., 1987, Stratigraphy, Chap.5, *in* Bird,
K.J., and Magoon, L.B., eds., Petroleum geology of the northern part of
the Arctic National Wildlife Refuge, northeastern Alaska:U.S. Geological
Survey Bulletin 1778, p. 37-59.

Blodgett, R.B., 1992, Taxonomy and paleobiogeographic affinities of an
Early Middle Devonian (Eifelian) gastropod faunule from the Livengood
quadrangle, east-central Alaska: Palaeontographica Abteilung A, v. 221,
p. 125-168.

Blodgett, R.B., and Clough, J.G., 1985, The Nixon Fork terrane - Part of
an in-situ peninsular extension of the Paleozoic North American
continent \[abs.\]: Geological Society of America Abstracts with
Programs, v. 17., p. 342.

Blodgett, R.B., Clough, J.G., Dutro, J.T., Jr., Ormiston, A.R., Palmer,
A.R., and Taylor, M.E., 1986, Age revisions for the Nanook Limestone and
Katakturuk Dolomite, northeastern Brooks Range, *in* Bartsch-Winkler,
Susan, and Reed, K.M., eds., Geologic studies in Alaska by the U.S.
Geological Survey during 1985: U.S. Geological Survey Circular 978, p.
5-10.

Blodgett, R.B., Clough, J.G., Harris, A.G., and Robinson, M.S., 1992,
The Mount Copleston Limestone, a new Lower Devonian formation in the
Shublik Moutnains, northeastern Brooks Range, Alaska, *in* Bradley,
D.S., and Ford, A.B., eds., Geologic studies in Alaska by the U.S.
Geological Survey, 1999, U.S. Geological Survey Bulletin 1999, p. 3-7.

Blodgett, R.B., and Gilbert, W.G., 1983, The Cheeneetnuk Limestone, a
new Early(?) to Middle Devonian Formation in the McGrath A-4 and A-5
quadrangles, west-central Alaska: Alaska Division of Geological and
Geophysical Surveys Professional Report 85, p. 1-6.

Ñ1992, Upper Devonian shallow-marine siliciclastic strata and associated
fauna and flora, Lime Hills D-4 quadrangle, southwest Alaska, *in*
Bradley, D.C., and Dusel-Bacon, Cynthia, eds., Geologic Studies in
Alaska by the U.S. Geological Survey: U.S. Geological Survey Bulletin
2041, p. 106-113.

Blodgett, R.B., Rohr, D.M., Harris, A.G., and Rong, Jia-yu, 1988, A
major unconformity between Upper Ordovician and Lower Devonian strata in
the Nanook Limestone, Shublik Mountains, northeastern Brooks Range, *in*
Galloway, J.P., and Hamilton, T.D., eds., Geologic studies in Alaska by
the U.S. Geological Survey during 1987: U.S. Geological Survey Circular
1016, p. 18-23.

Boak, J.M., Turner, D.L., Henry, D.J., Moore, T.E., and Wallace, W.K.,
1987, Petrology and K-Ar ages of the Misheguk igneous sequence, an
allochthonous mafic and ultramafic complex, and its metamorphic aureole,
western Brooks Range, Alaska, *in* Tailleur, I.L., and Weimer, Paul,
eds., Alaskan North Slope Geology: Los Angeles, Society of Economic
Paleontologists and Mineralogists, Pacific Section, and Anchorage Alaska
Geological Society, v. 2, p. 737-745.

Box, S.E., 1985a, Geologic setting of high-pressure metamorphic rocks,
Cape Newenham area, southwestern Alaska, *in* Bartsch-Winkler, Susan,
ed., The United States Geological Survey in Alaska: Accomplishments
during 1984: U.S. Geological Survey Circular 967, p. 37-42.

Ñ1985b, Terrane analysis, northern Bristol Bay region, southwestern
Alaska, *in* Bartsch-Winkler, Susan, ed., The United States Geological
Survey in Alaska: Accomplishments during 1984: U.S. Geological Survey
Circular 967, p. 32-36.

Box, S.E., and Elder, W.P., 1992, Depositional and biostratigraphic
framework of the Upper Cretaceous Kuskokwim Group, southwestern, Alaska,
*in* Bradley, D.C., and Ford, A.B., eds., Geologic studies in Alaska by
the U.S. Geological Survey, 1990: U.S. Geological Survey Bulletin 1999,
p. 8-16.

Box, S.E., Moll-Stalcup, E.J., Frost, T.P., and Murphy, J.M., 1992,
Preliminary geologic map o the Bethel and southern Russian Mission 1¡ x
3¡ quadrangles, southwestern Alaska: U.S. Geological Survey
Miscellaneous Field Studies Map MF-\_\_\_\_\_, scale 1: 250,000.

Box, S.E., Moll-Stalcup, E.J., and Wooden, J.L., 1990, Kilbuck terrane:
Oldest-known rocks in Alaska: Geology, v. 18, p. 1219-1222.

Box, S.E., and Patton, W.W., Jr., 1989, Igneous history of the Koyukuk
terrane, western Alaska: Constraints on the origin, evolution, and
ultimate collision of an accreted island arc terrane: Journal of
Geophysical Research, v. 94, p. 15,843-15,867.

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, 1 sheet, scale 1:
250,000.

Bradley, D.C., and Kusky, T.M., 1992, Deformation history of the McHugh
Complex, Seldovia quadrangle, south-central Alaska, *in* Bradley, D.C.,
and Ford, A.B., eds., Geologic studies in Alaska by the U.S. Geological
Survey, 1990: U.S. Geological Survey Bulletin 1999, p. 17-32.

Brew, D.A., 1988, Latest Mesozoic and Cenozoic igneous rocks of
southeastern Alaska\--a synopsis: U.S. Geological Survey Open-File
Report 88-405, 52 p.

Brew, D.A., and Karl, S.M., 1988a, A reexamination of the contacts and
other features of the Gravina Belt, southeastern Alaska \[abs\]:
Geological Society of America, Abstracts with Programs, v. 20, no. 7, p.
111.

Ñ1988b, A reexamination of the contacts and other features of the
Gravina belt, southeastern Alaska, *in* Galloway, J.P., and Hamilton,
T.D., eds., Geologic studies in Alaska by the U.S. Geological Survey
during 1987: U.S. Geological Survey Circular 1016, p. 143-146.

Ñ1988c, A reexamination of the contacts and other features of the
Gravina belt, southeastern Alaska, Supplemental data: U.S. Geological
Survey Open-File Report 88-652, 8 p.

Brew, D.A., Karl, S.M., Barnes, D.F., Jachens, R.C., Ford, A.B., and
Horner, R., 1991, A northern Cordilleran ocean-continent transect: Sitka
Sound to Atlin Lake, British Columbia: Canadian Journal of Earth
Sciences, v. 28, no. 6, p. 840-853.

Brew, D.A., Karl, S.M., and Miller, J.W., 1988, Megafossils *(Buchia)*
indicate Late Jurassic age for part of Kelp Bay Group on Baranof Island,
southeastern Alaska, *in* Galloway, J.P., and Hamilton, T.D., eds.,
Geologic studies in Alaska by the U.S. Geological Survey during 1987
U.S. Geological Survey Circular 1016, p. 147-149.

Brew, D.A., Ovenshine, A.T., Karl, S.M., and Hunt, S.J., 1984,
Preliminary reconnaissance geologic map of the Petersburg and parts of
the Port Alexander and Sumdum 1:250,000 quadrangles, southeastern
Alaska: U.S. Geological Survey Open-File Report 84-405, 2 sheets, 43 p.
pamphlet.

Brewer, W.M., 1982, Stratigraphy, structure, and metamorphism of the
Mount Deborah area, central Alaska Range, Alaska \[Ph.D. thesis\]:
Madison, University of Wisconsin, 318 p.

BrosgŽ, 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.

BrosgŽ, W.P., and Reiser, H.N., 1969, Preliminary geologic map of the
Coleen quadrangle, Alaska: U.S. Geological Survey Open-File Report OF
69-370, 1 sheet, scale 1:63,360.

BrosgŽ, W.P., and Tailleur, I.L., 1970, Depositional history of northern
Alaska, *in* Adkison, W.L., and BrosgŽ, M.M., eds., Proceedings of the
geological seminar on the North Slope of Alaska:American Association of
Petroleum Geologics Pacific Section Meeting, Los Angeles, p. D1-D18.

BrosgŽ, W.P., Dutro, J.T., Jr., Mangus, M.D., and Reiser, H.N., 1962,
Paleozoic sequence in eastern Brooks Range, Alaska:American Association
Petroleum Geologists Bulletin, v. 46, p. 2,174-2,198.

Bundtzen, T.K., and Gilbert, W.G., 1983, Outline of the geology and
mineral resources of the upper Kuskokwim region, southwest Alaska, *in*
Sisson, Alex, ed., Symposium on energy and mineral resoutces of western
Alaska: Alaska Geological Society, v. 3, p. 98-119.

Burns, L.E., 1985, The Border Ranges ultramafic and mafic complex,
south-central Alaska: Cumulate fractionates of island-arc volcanics:
Canadian Journal of Earth Sciences, v. 22, p. 1020-1038.

Cady, W.M., Wallace, R.E., Hoare, J.M., and Webber, E.J., 1955, The
central Kuskokwim region, Alaska: U.S. Geological Survey Professional
Paper 268, 132 p.

Campbell, R.H., 1967, Areal geology in the vicinity of the Chariot site,
Lisburne Peninsula, northwest Alaska:U.S. Geological Survey Professional
Paper 395, 71 p.

Campbell, R.B., and Dodds, C.J., 1982a, Geology of s.w. Kluane Lake map
area, Yukon Territory: Geological Survey of Canada Maps 115F and 115G,
Open File 829, scale 1:250,000.

Ñ1982b, Geology of the Mount St. Elias map area, Yukon Territory:
Geological Survey of Canada Maps 115B and 115C, Open File 830, scale
1:250,000.

Chapman, R.M., Weber, F.R., and Taber, Bond, 1971, Preliminary geologic
map of the Livengood quadrangle, Alask: U.S. Geological Survey Open-File
Report 71-66, 1 sheet, scale 1:250,000.

Churkin, Michael, Jr., Carter, Claire, and Trexler, J.H., Jr., 1980,
Collision-deformed Paleozoic continental margin of Alaska\--foundation
for microplate accretion: Geological Society of America Bulletin, v. 91,
p. 648-654.

Churkin, Michael, 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.

Churkin, Michael, Jr., Nokleberg, W.J., and Huie, Carl, 1979,
Collision-deformed Paleozoic continental margin, western Brooks Range,
Alaska: Geology, v. 7, p. 379-383.

Clough, J.G., and Blodgett, R.B., 1985, Comparative study of the
sedimentology and paleoeocology of middle Paleozoic algal and
coral-stromatoporoid reefs in Alaska: Proceedings of the Fifth
International Coral Reef Congress, Tahiti, v. 3, p. 184-190.

Coney, P.J., Jones, D.L., and Monger, J.W.H., 1980, Cordilleran suspect
terranes: Nature, v. 288, p. 329-333.

Connelly, William, 1978, Uyak Complex, Kodiak Islands, Alaska: A
Cretaceous subduction complex: Geological Society of America Bulletin,
v. 89, p. 775-769.

Connelly, William, and Moore, J.C.., 1979, Geologic map of the northwest
side of the Kodiak and ;adjacent islands, Alaska: U.S. Geological Survey
Miscellaneous Field Studies Map MF-1047, 2 sheets, scale 1:250,000.

Csejtey, BŽla, Jr., Mullen, M.W., Cox, D.P., and Stricker, G.D., 1992,
Geology and geochronology of the Healy quadrangle, Alaska: U.S.
Geological Survey Miscellaneous Investigations Series Map I-1961, 2
sheets, scale 1:250,000, 63 p.

Davidson, Cameron, and Hollister, L.S., 1992, Role of melt in the
formation of a deep-crustal compressive shear zone: The Maclaren Glacier
metamorphic belt, south-central Alaska: Tectonics, v. 11, p. 348-359.

Decker, John, Wilson, F.H., and Turner, D.L., 1980, Mid-Cretaceous
subduction event in southeastern Alaska \[abs.\]: Geological Society of
America Abstracts with Programs, v. 12, p. 103.

Dillon, J.T., 1989, Structure and stratigraphy of the southern Brooks
Range and northern Koyukuk basin near the Dalton Highway, *in* Mull,
C.G., and Adams, K.E., eds., Dalton Highway, Yukon River to Prudhoe Bay,
Alaska:Alaska Division of Geological and Geophysical Surveys Guidebook
7, v. 2, p. 157-187.

Dillon, J.T., Harris, A.G., and Durtro, J.R., Jr., 1987, Preliminary
description and correlation of lower Paleozoic fossil-bearing strata in
the Snowden Mountain area of the south-central Brooks Range, Alaska,
*in* Taillerur, I.L., and Weimer, Paul, eds., Alaskan North Slope
Geology: Pacific Section, Society of Economic Paleontologists and
Mineralogists, Bakersfield, Calif. v. 50, p. 337-345.

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.

Dover, J.H., 1990, Geology of east-central Alaska: U.S. Geological
Survey Open-File Report 90-289, 96p.

Dutro, J.T., Jr., BrosgŽ, W.P., Lanphere, M.A., and Reiser, H.N., 1976,
Geologic significance of Doonerak structural high, central Brooks Range,
Alaska: American Association of Petroleum Geologists Bulletin, v. 60, p.
952-961.

Dumoulin, J.A., 1987, Sandstone composition of the Valdez and Orca
Groups, Prince William Sound, Alaska: U.S. Geological Survey Bulletin
1774, 37 p.

Ñ1988, Sandstone petrographic evidence and the Chugach-Prince William
terrane boundary in southern Alaska: Geology, v. 16, p. 456-460.

Dumoulin, J.A., and Harris, A.G., 1987, Lower Paleozoic carbonate rocks
of the Baird Mountains quadrangle, western Brooks Range, Alaska, *in*
Tailleur, I.L., and Weimer, Paul, eds., Alaska North Slope Geology:
Pacific Section, Society of Economic Paleontologists and Mineralogists,
Bakersfield, California, v. 50, p. 311-336.

Dusel-Bacon, Cynthia, 1991, Metamorphic history of Alaska: U.S.
Geological Survey Open-File Report 91-556, 48 p., 2 sheets, scale
1:2,500,000.

Dusel-Bacon, Cynthia and Hansen, V.L., 1992, High-pressure,
amphibolite-facies metamorphism and deformation within the Yukon-Tanana
and Taylor Mountain terranes, eastern Alaska, *in* Bradley, D.C., and
Dusel-Bacon, Cynthia, eds, Geological Studies in Alaska by the U.S.
Geological Survey, 1991: U.S. Geological Survey Bulletin 2041, p.
140-159.

Duttweiler-Kelley, Karen, 1990, Interpretation of geochemical data from
Admiralty Island, Alaska\--Evidence for volcanogenic massive sulfide
mineralization, *in* Goldfarb, R.J., Nash, T.J., and Stoerer, J.W.,
eds., Geochemical Studies in Alaska by the U.S. Geological Survey, 1989:
U.S. Geological Survey Bulletin 1950, p. A1-A9.

Eberlein, G.D., Churkin, M., Jr., Carter, C., Berg, H.C., and Ovenshine,
A.T., 1983, Geology of the Craig quadrangle, Alaska: U.S. Geological
Survey Open-File Report 83-91, 4 sheets, 54 p.

Fernette, Gregory, and Cleveland, Gregory, 1984, Geology of the Miss
Molly molybdenum propsect, Toyonek C-6 quadrangle, Alaska: Alaska
Division of Geological and Geophysical Surveys Professional Report 86,
p. 35-41.

Ford, A.B., and Brew, D.A., 1988, The Douglas Island Volcanics;
basaltic-rift\--not andesitic-arc\--volcanism of the \"Gravina-Nutzotin
belt,\" northern southeastern Alaska (abs.): Geological Society of
America, Abstracts with Programs, v. 20, no. 7, p. 111.

Foster, H.L., 1976, Geologic map of the Eagle quadrangle, Alaska: U.S.
Geological Survey Miscellaneous Investigations Map Series I-922, scale
1:250,000.

Foster, H.L., Keith, T.E.C., and Menzie, W.D., 1987, Geology of
east-central Alaska: U.S. Geological Survey Open-File Report 87-188, 59
p.

Gardner, M.C., Bergman, S.C., Cushing, G.W., MacKevett, E.M., Jr.,
Plafker, G., Campbell, R.B., Dodds, C.J., McClelland, W.C., and Mueller,
P.A., 1988, Pennsylvanian pluton stitching of Wrangellia and the
Alexander terrane, Wrangell Mountains, Alaska: Geology, v. 16, p.
967-971.

Gehrels, G.E., 1990, Late Proterozoic-Cambrian metamorphic basement of
the Alexander terrane on Long and Dall Islands, southeast Alaska:
Geological Society of America Bulletin, v. 102, p. 760-767.

Gehrels, G.E., 1991, Geologic map of Long Island and southern and
central Dall Island, southeastern Alaska: U.S. Geological Survey Map
MF-2146, 1 sheet.

Gehrels, G.E., and Berg, H.C., 1992, Geologic map of southeastern
Alaska: U.S. Geological Survey Miscellaneous Investigations Series Map
I-1867, 1 sheet, scale 1:600,000, 24 p.

Gehrels, G.E., McClelland, W.C., 1992, Geology of the western flank of
the Coast Mountains between Cape Fanshaw and Taku Inlet, southeastern
Alaska: Tectonics, v. 11, p. 567-585.

Gehrels, G.E., McClelland, W.C., Samson, S.D., Patchett, P.J., and
Jackson, J.L., 1990, Ancient continental margin assemblage in the
northern Coast Mountains, southeast Alaska and northwest Canada:
Geology, v. 18, p. 208-211.

Gehrels, G.E., and Saleeby, J.B.,1986, Geologic map of southern Prince
of Wales Island, southeastern Alaska: U.S. Geological Survey Open-File
Report 86-275, 33 p.

Gehrels, G.E., and Saleeby, J.B.,1987, Geology of southern Prince of
Wales Island, southeastern Alaska: Geological Society of America
Bulletin, v. 98, p. 123-137.

Gehrels, G.E., Saleeby, J.B., and Berg, H,C., 1987, Geology of Annette,
Gravina, and Duke Islands, southeastern Alaska: Canadian Journal of
Earth Sciences, v. 24, p. 866-881.

Gergen, L.D., Decker, J.E., and Plafker, George, 1988, A comparative
study of sandstone from the Wilber Creek, Cascaden Ridge, and Wickersham
units in the Livengood quadrangle, *in* Galloway, J.P., and Hamilton,
T.D., eds., Geologic Studies in Alaska by the United States Geological
Survey during 1987: U.S. Geological Survey Circular 1016, p. 57-60.

Gilbert, W.G., and Bundtzen, T.K., 1984, Stratigraphic relationships
between Dillinger and Mystic terranes, western Alaska Range, Alaska
\[abs.\]: Geological Society of America Abstracts with Programs, v. 16,
p. 286.

Gilbert, W.G., Nye, C.J., and Sherwood, K.W., 1984, Stratigraphy,
petrology, and geochemistry of Upper Triassic rocks from the Pingston
and McKinley terranes, central Alaska Range: Alaska Division of
Geological and Geophysical Surveys Report of Investigation 84-30, 14 p.

Gottschalk, R.R., Jr., 1990, Structural evolution of the schist belt,
south-central Brooks Range fold and thrust belt, Alaska: Journal of
Structural Geology, v. 12, p. 453-469.

Grantz, Arthur and May, S.D., 1983, Rifting history and structural
development of the continental margin north of Alaska, *in* Watkins,
J.S. and Drake, C., eds., Continental margin processes: American
Association of Petroleum Geologists Memoir 34, p. 77-100.

Grantz, Arthur, Moore, T.E., and Roeske, S.M., 1991, North American
Continent-Ocean transect A-3: Gulf of Alasa to Arctic Ocean, Geological
Society of America Continental/Ocean Transect A-3: Geological Society of
America, Boulder, Colorado, 72 p., 3 sheets, scale 1:500,000.

Grantz, Arthur, Tailleur, I.L., and Carter, Claire, 1983, Tectonic
significance of Silurian and Ordovician graptolites from the Lisburne
Peninsula, northwest Alaska \[abs.\]: Geological Society of America
Abstracts with Programs, v. 15, no. 5, p. 274.

Haeussler, P.J., 1992, Structural evolution of an arc-basin: The Gravina
belt in central southeastern Alaska: Tectonics, v. 11, p. 1245-1265.

Hitzman, M.W., Smith, T.E., and Proffett, J.M., 1982, Bedrock geology of
the Ambler district, southwestern Brooks Range, Alaska: Alaska Division
of Geologic and Geophysical Surveys, Geologic Report 75, 2 pls., scale
1:63,360.

Hoare, J.M., and Coonrad, W.L., 1978, Geologic map of the Goodnews and
Hagemeister Island quadrangles region, southwestern Alaska: U. S.
Geological Survey Open-File Report 78-9-B, scale 1:250,000.

Ñ1979, The Kanektok metamorphic complex, a rootless belt of Precambrian
rocks in southwestern 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. B72-B74.

Hoare, J.M., and Jones, D.L., 1981, Lower Paleozoic radiolarian chert
and associated rocks in the Tikchik Lakes area, southwestern Alaska,
*in* Albert, N.R.D., and Hudson, Travis, eds., The United States
Geological Survey in Alaska: Accomplishments during 1979: U.S.
Geological Survey Circular 823-B, p. 44-45.

Howell, D.G., Johnsson, M.J., Underwood, M.B., Huafu, Lu, and Hillhouse,
J.W., 1992, Tectonic evolution of the Kandik region, east-central
Alaska: Preliminary interpretations, *in* Bradley, D.C., and Ford, A.B.,
eds., Geologic studies in Alaska by the U.S. Geological Survey, 1990:
U.S. Geological Survey Bulletin 1999, p. 127-140.

Howell, D.G., Jones, D.L., and Schermer, E.R., 1985,
Tectonostratigraphic terranes of the Circum-Pacific region: Principles
of terrane analysis, *in* Howell, D.G., ed., Tectonostratigraphic
terranes of the Circum-Pacific region: Circum-Pacific Council for Energy
and Mineral Resources, Houston, Texas, p. 3-31.

Howell, D.G., and Wiley, T.J., 1987, Crustal evolution of northern
Alaska inferred from sedimentology and structural relations of the
Kandik area: Tectonics, v. 6., p. 619-631.

Hudson, Travis, 1977, Geologic map of Seward Peninsula, Alaska: U.S.
Geological Survey Open-File Report 77-796-A, scale 1:1,000,000.

Hudson, Travis, and Plafker, George, 1982, Paleogene metamorphism of an
accretionary flysch terrane, eastern Gulf of Alaska: Geological Society
of America Bulletin, v. 93, p. 1280-1290.

Imlay, R.W., and Detterman, R.L., 1973, Jurassic paleobiogeography of
Alaska: U.S. Geological Survey Professional Paper 801, 34 p.

Johnson, B.R., and Karl, S.M., 1985, Geologic map of western Chichagof
and Yakobi Islands, southeastern Alaska: U.S. Geological Survey Map
I-1506, 1 sheet, 15 p. pamphlet.

Jones, D.L., Coney, P.J., Harms, T.A., and Dillon, J.T., 1988,
Interpretive geologic map and supporting radiolarian data from the
Angayucham terrane, Coldfoot area, southern Brooks Range, Alaska: U.S.
Geological Survey Miscellaneous Field Studies Map MF-1993, 1 sheet,
scale 1:63,360.

Jones, D.L., Howell, D.G., Coney, P.J., and Monger, J.W.H., 1983,
Recognition, character, and analysis of tectonostratigraphic terranes in
western North America, *in* Hashimoto, M., and Uyeda, S., eds.,
Accretion tectonics in the circum-Pacific regions; proceedings of the
Oji International Seminar on Accretion Tectonics, Japan, 1981: Advances
in Earth and Planetary Sciences, Tokyo, Terra Scientific Publishing
Company, p. 21-35.

Jones, D.L., Silberling, N.J., Berg, H.C., and Plafker, George, 1981,
Map showing tectonostratigraphic terranes of Alaska, columnar sections,
and summary description of terranes: U.S. Geological Survey Open-File
Report 81-792, 20 p., 2 sheets, scale 1:2,500,000.

Jones, D.L., Silberling, N.J., Coney, P.J., and Plafker, George, 1986,
Collision tectonics in the Cordillera of western North America:examples
from Alaska, *in* Coward, M.P., and Ries, A.C., (eds.), Collision
Tectonics:Geological Society Special Publication no. 19, p. 367-387.

Ñ1987, Lithotectonic terrane map of Alaska (West of the 141st Meridan):
U.S. Geological Survey Map MF-1874-A, 1 sheet, scale 1:2,500,000.

Jones, D.L., Silberling, N.J., Csejtey, BŽla, Jr., Nelson, W.H., and
Blome, C.D., 1980, Age and structural significance of ophiolite and
adjoining rocks in the Upper Chulitna district, south-central Alaska:
U.S. Geological Survey Professional Paper 1121-A, 21 p.

Jones, D.L., Silberling, N.J., Gilbert, Wyatt, and Coney, Peter, 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.

Jones, D.L., Silberling, N.J., and Hillhouse, J.W., 1977, Wrangellia\--a
displaced terrane in northwestern North America: Canadian Journal of
Earth Sciences, v. 14, p. 2565-2577.

Karl, S.M., 1992, Arc extensional basin geochemical and tectonic
affinities for the Maiyumerak basalts in the western Brooks Range, *in*
Bradley, D.C., and Ford, A.B., eds., Geologic Studies by the U.S.
Geological Survey, 1990: U.S. Geological Survey Bulletin 1999, p.
141-155.

Karl, S.M., and Aleinikoff, J.N., 1990, Proterozoic U-Pb zircon age of
granite in the Kallarichuk Hills, western Brooks Range, Alaska: Evidence
for PreCambrian basement in the schist belt, *in* Dover, J.H., and
Galloway, J.P., eds., Geologica studies in Alaska by the U.S. Geological
Survey, 1989: U.S. Geological Survey Bulletin 1946, p. 95-100.

Karl, S.M., Brew, D.A., and Wardlaw, B.R., 1990, Significance of
Triassic marble at Nakwasina Sound, southeastern Alaska, *in* Dover,
J.H., and Galloway, J.P., eds., Geologic studies in Alaska by the U.S.
Geological Survey in 1989: U.S. Geological Survey Bulletin 1946, p.
21-28.

Karl, S.M., Dumoulin, J.A., Ellersieck, Inyo, Harris, A.G., and Schmidt,
J.M., 1989, Preliminary geologic map of the Baird Mountains quadrangle,
Alaska: U.S. Geological Survey Open-File Report 89-551, 65 p., 1 sheet,
scale 1:250,000.

Keith, T.E., Foster, H.L., Foster, R.L., Post, E.V., and Lehmbeck, W.L.,
1981, Geology of an alpine-type peridotite in the Mount Sorenson area,
east-central Alaska: U.S. Geological Survey Professional Paper 1170-A, 9
p.

Kirschner, C.W., 1988. Map showing sedimentary basins of onshore and
continental shelf areas: U.S. Geological Survey Miscellaneous
Investigations Series Map I-873, 1 sheet, scale 1:2,500,000.

Lane, H.R., and Ormiston, A.R., 1979, Siluro-Devonian biostratigraphy of
the Salmontrout River area, east-central Alaska: Geologica et
Palaeontologica, v. 13, p. 39-36.

Loney, R.A., Brew, D.A., Muffler, L.J.P., and Pomeroy, J.S., 1975,
Reconnaissance geology of Chichagof, Baranof, and Kruzof Islands,
Alaska: U.S. Geological Survey Professional Paper 792, 105 p.

Loney, R.A., and Himmelberg, G.R., 1985, Ophiolite ultramafic rocks of
the Jade Mountains-Cosmos Hills area, southwestern Brooks Range, *in*
Bartsch-Winkler, Susan, ed., The United States Geological Survey in
Alaska: Accomplishments during 1984: U.S. Geological Survey Circular
967, p. 13-15.

Ñ1988, Ultramafic rocks of the Livengood terrane, *in* Galloway, J.P.,
and Hamilton, T.D., eds., Geologic Studies in Alaska the United States
Geological Survey during 1987: U.S. Geological Survey Circular 1016, p.
62-70.

Ñ1989, The Kanuti ophiolite, Alaska: Journal of Geophysical Research, v.
94, p. 15,869-15,900.

Lull, J.S., and Plafker, George, 1990, Geochemistry and paleotectonic
implications of metabasaltic rocks in the Valdez Group, southern Alaska:
U.S. Geological Survey Bulletin 1946, p. 29-38.

McClelland, W.C., and Gehrels, G.E., 1990, Geology of the Duncan Canal
shear zone: Evidence for Early to Middle Jurassic deformation of the
Alexander terrane, southeastern Alaska: Geological Society of America
Bulletin, v. 102, p. 1378-1392.

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

Martin, A.J., 1970, Structure and tectonic history of the western Brooks
Range, De Long Mountains and Lisburne Hills, northern Alaska: Geological
Society of America Bulletin, v. 81, p. 3605-3622.

Mayfield, C.F., Tailleur, I.L., and Ellersieck, Inyo, 1988,
Stratigraphy, structure, and palinspastic synthesis of the western
Brooks Range, northwestern Alaska, *in* Gryc, George, ed., Geology and
Exploration of the National Petroleum Reserve in Alaska, 1974 to 1982:
U.S. Geological Survey Professional Paper 1399, p. 143-186.

Mayfield, C.F., Tailleur, I.L., Mull, C.G., and Sable, E.G., 1978,
Bedrock geologic map of the south half of National Petroleum Reserve in
Alaska: U.S. Geological Survey Open-File Report 78-70-B, scale
1:500,000.

McClelland, W.C., and Gehrels, G.E., 1992, Upper Jurassic-Lower
Cretaceous basinal strata along the Cordilleran margin: Implications for
the accretionary history of the Alexander-Wrangellia-Peninsular terrane:
Tectonics, v. 11, p. 832-835.

McClelland, W.C., Gehrels, G.E., Samson, S.D., and Patchett, P.J., 1991,
Protolith relations of the Gravina belt and Yukon-Tanana terrane in
central southeastern Alaska: Journal of Geology, v. 100, p. 107-123.

Ñ1992, Structural and geochronologic relations along the western flank
of the Coast mountains batholith: Stikine River to Cape Fanshaw, central
southeastern Alaska: Journal of Structural Geology, v. 14, p. 475-489.

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, p.
209-223.

Moll-Stalcup, E.J., 1990, Latest Cretaceous and Cenozoic magmatism in
mainland Alaska: U.S. Geological Survey Open-File Report 90-84, 80 p.

Monger, J.W.H., and Berg, H.C., 1987, Lithotectonic terrane map of
western Canada and southeastern Alaska: U.S. Geological Survey Map
MF-1874-B, one sheet, 12 p.

Monger, J.W.H., Price, R.A., and Tempelman-Kluit, D.J., 1982, Tectonic
accretion and the origin of the two major metamorphic and plutonic
weilts in the Canadian Cordillera: Geology, v.10, p. 70-75.

Moore, J.C., Byrne, T., Plumley, P.W., Reid, M., Gibbons, H., and Coe,
R.S., 1983, Paleogene evolution of the Kodiak Islands, Alaska:
Consequences of ridge-trench interaction in a more southerly latitude:
Tectonics, v. 2, p. 265-293.

Moore, T.E., 1992, The Arctic Alaska superterrane, *in* Bradley, D.C.,
and Dusel-Bacon, Cynthia, eds., Geologic studies in Alaska by the U.S.
Geological Survey, 1991: U.S. Geological Survey Bulletin 2041, p.
238-244

Moore, T.E., and Mull, Gil, 1989, Geology of the Brooks Range and North
Slope, *in* Nokleberg, W.J., and Fisher, M.A., eds., Alaskan Geological
and Geophysical Transect: Field Trip Guidebook T104, 28th International
Geological Congress, p. 107-131.

Moore, T.E, and Murphy, J.M., 1989, Nature of the basal contact of the
Tozitna terrane along the Dalton Highway, northeast Tanana quadrangle,
Alaska, *in* Dover, J.H., and Galloway, J.P., eds., Geologic studies in
Alaska by the U.S. Geological Survey, 1988: U.S. Geological Survey
Bulletin 1903, p. 46-53.

Moore, T.E., and Nokleberg, W.J., 1988, Stratigraphy, sedimentology, and
structure of the Wickersham terrane in the Cache Mountain area,
east-central Alaska, *in* Galloway, J.P., and Hamilton, T.D., eds.,
Geologic Studies in Alaska the United States Geological Survey during
1987: U.S. Geological Survey Circular 1016, p. 75-80.

Moore, T.E., Wallace, W.K., Bird, K.J., Karl, S.M., Mull, C.G., and
Dillon, J.T., 1992, Stratigraphy, structure, and geologic synthesis of
northern Alaska: U.S. Geological Survey Open-File Report 92-330, 283 p,
1 plate.

Monger, J.W.H., and Berg, H.C., 1987, Lithotectonic terrane map of
western Canada and southeastern Alaska: U. S. Geological Survey
Miscellaneous Field Studies Map MF-1874-B, 1 sheet, scale 1:2,500,000,
12 p.

Mull, C.G., Tailleur, I.L., Mayfield, C.F., Ellersieck, Inyo, and
Curtis, S.M., 1982, New upper Paleozoic and Lower Mesozoic stratigraphic
units, central and western Brooks Range, Alaska: American Association of
Petroleum Geologists Bulletin, v. 66, p. 348-362.

Murchey, Benita, and Harris, A.G., 1985, Devonian to Jurassic
sedimentary rocks in the Angayucham Mountains of Alaska; possible
seamount or oceanic plateau deposits \[abs.\]: Eos, v. 66, p. 1102.

Murchey, Benita L., Jones, David L., Holdsworth, Brian K., and Wardlaw,
Bruce R., 1988, Distribution patterns of facies, radiolarians, and
conodonts in the Mississippian to Jurassic Siliceous rocks of the
northern Brooks Range, Alaska: U.S. Geological Survey Professional Paper
1399, p. 697-724.

0Murphy, J.M., 1987, Early Cretaceous cessation of terrane accretion,
northern Eek Mountains, southwestern Alaska, *in* Hamilton, T.D., and
Galloway, J.P., eds., Geologic Studies in Alaska by the U.S. Geological
Survey during 1986: U.S. Geological Survey Circular 998, p. 83-85.

Murphy, J.M., and Patton, W.W., Jr., 1988, Geologic setting and
petrography of the phyllite and metagraywacke thrust panel,
north-central Alaska, *in* Galloway, J.P., and Hamilton, T.D., eds.,
Geologic studies in Alaska by the U.S. Geological Survey during
1987:U.S. Geological Survey Circular 1016, p 104-108.

Nelson, S.W., 1992, Ophiolitic complexes for the Gulf of Alaska: U.S.
Geological Survey Open-File Report 92-20C, 10 p.

Nelson, S.W., Dumoulin, J.A., and Miller, M.L., 1985, Geologic map of
the Chugach National Forest, Alaska: U.S. Geological Survey
Miscellaneous Field Studies Map MF-1645-B, 16 p., 1 sheet, scale
1:250,000.

Nichols, K.M., and Silberling, N.J., 1979, Early Triassic (Smithian)
ammonites of paleoequatorial affinity from the Chulitna terrane,
south-central Alaska: U.S. Geological Survey Professional Paper 1121-B,
p. B1-B25.

Nilsen, T.H., 1981, Upper Devonian and Lower Mississippian redbeds,
Brooks Range, Alaska, *in* Miall, A.D., ed, Sedimentation and tectonics
in alluvial basins: Geological Association of Canada Special Paper 23,
p. 187-219.

Ñ1989, Stratigraphy and sedimentology of the mid-Cretaceous deposits of
the Yukon-Koyukuk basin, west-central Alaska: Journal of Geophysical
Research, v. 94, p. 15,925-15,940.

Nokleberg, W.J., Aleinikoff, J.N. Lange, I.M., Silva, S.R., Miyaoka,
R.T., Schwab, C.E., and Zehner, R.E., 1992, Preliminary geologic map of
the Mount Hayes quadrangle, eastern Alaska Range, Alaska: U.S.
Geological Survey Open-File Report 92-594, 1 sheet, scale 1:250,000, 39
p.

Nokleberg, W.J., Foster, H.L., and Aleinikoff, J.N., 1989a, Geology of
the northern Copper River Basin, eastern Alaska Range, and southern
Yukon-Tanana Basin, southern and east-central Alaska, *in* Nokleberg,
W.J., and Fisher, M.A., eds., Alaskan Geological and Geophysical
Transect: Field Trip Guidebook T104, 28th International Geological
Congress, p. 34 to 63.

Nokleberg, W.J., Jones, D.L., and Silberling, N.J., 1985, Origin,
migration, and accretion of Andean-type arc and island arc
tectonostratigraphic terranes in the southern Mount Hayes quadrangle and
adjacent areas of the eastern Alaska Range, Alaska: Geological Society
of America Bulletin, v. 96, p. 1251-1270.

Nokleberg, W.J., Plafker, George, Lull, J.S., Wallace, W.K., and
Winkler, G.W., 1989b, Structural analysis of the southern Peninsular,
southern Wrangellia, and northern Chugach terranes along the
Trans-Alaskan Crustal Transect (TACT), northern Chugach Mountains,
Alaska: Journal of Geophysical Research, v. 94, p. 4297-5320.

Nokleberg, W.J., and Winkler, G.R., 1982, Stratiform zinc-lead deposits
in the Drenchwater Creek area, Howard Pass quadrangle, northwestern
Brooks Range, Alaska: U.S. Geological Survey Professional Paper 1209, 22
p.

Pallister, J.S., Budahn, J.R., and Murchey, B.L., 1989, Pillow basalts
of the Angayucham terrane: Oceanic plateau and island crust accreted to
the Brooks Range: Journal of Geophysical Research, v. 94, p.
15,901-15,924.

Pallister, J.S., and Carlson, Christine, 1988, Bedrock geologic map of
the Angayucham Mountains, Alaska: U.S. Geological Survey Miscellaneous
Field Studies Map MF-2024, 1 sheet, scale 1:63,360.

Palmer, A.R., 1983, The Decade of North American Geology 1983 Geologic
Time Scale: Geology, v. 11, no. 9, p. 503-504.

Palmer, A.R., Egbert, R.M., Sullivan, R., and Knoth, J.S., 1985,
Cambrian trilobites with Siberian affinities, souithwestern Alaska
\[abs.\]: American Association of Petroleum Geologists Bulletin, v. 69,
p. 295.

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

Ñ1991, Deep crustal composition of the Yukon-Koyukuk basin, Alaska
\[abs.\]: Geological Society of America Abstracts with Programs, v. 23,
p. 88.

Ñ1992a, Ophiolitic terrane of western Brooks Range, Alaska: U.S.
Geological Survey Open-File Report 92-90D, 8 p.

Ñ1992b, Ophiolitic terrane bordering the Yukon-Koyukuk basin, Alaska:
U.S. Geological Survey Open-File Report 92-90F, 8 p.

Patton, W.W., Jr., Box, S.E., Moll-Stalcup, E.J., and Miller, T.P.,
1989, Geology of west-central Alaska: U.S. Geological Survey Open-File
Report 89-554, 53 p.

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

Patton, W.W., Jr., Murphy, J.M., Burns, L.E., Nelson, S.W., and Box,
S.E., 1992, Geologic map of ophiolitic and associated volcanic arc and
metamorphic terranes of Alaska (west of the 141st meridian): U.S.
Geological Survey Open-File Report 92-20A, 1 sheet, scale 1:2,500,000.

Patton, W.W., Jr., Stern, T.W., Arth, J.G., and Carlson, Christine,
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., BrosgŽ, W.P., and Lanphere, M.A.,
1977, Preliminary report on ophiolites of northern and western Alaska,
*in* Coleman, R.G., and Irwin, W.P., eds., North American ophiolites:
Oregon Department of Geology and Mineral Industries Bulletin 95, p.
51-57.

Pavlis, T.L., 1983, Pre-Cretaceous crystalline rocks of the western
Chugach Mountains, Alaska: Nature of the basement of the Jurassic
Peninsular terrane: Geological Society of America Bulletin, v. 94, p.
1329-1344.

Pavlis, T.L., Sisson, V.B., Foster, H.L., Nokleberg, W.J., and Plafker,
George, 1993, Mid-Cretaceous extension tectonics of the Yukon-Tanana
terrane, Trans-Alaskan Crustal Transect (TACT), east-central Alaska:
Tectonics, p 103-122.

Pessel, G.H., Reifenstuhl, R.R., and Albanese, M.D., 1987, Regional
geology, Chapter 2, *in* Smith, T.E., Pessel, G.H., and Wiltse, M.A.,
eds., Mineral assessment of the Lime Peak-Mt. Prindle area, Alaska,
Volume 1, Alaska Division Geological and Geophysical Surveys, Fairbanks,
Alaska, p. 2-1 to 2-41.

Plafker, George, 1987, Regional geology and petroleum potential of the
northern Gulf of Alaska continental margin, *in* Scholl, D.W., Grantz,
Arthur, and Vedder, J.G., eds., Geology and resource potential of the
continental margin of western North America and adjacent ocean basins:
Circum-Pacific Council for Energy and Mineral Resources Earth Science
Seires, v. 6, p. 11/1-11/38.

Ñ1990, Regional geology and tectonic evolution of Alaska and adjacent
parts of the northeast Pacific ocean margin: Proceedings of the Pacific
Rim Congress 90, Australasian Insitute of Mining and Metallurgy,
Queensland, Australia, p. 841-853.

Plafker, George, Blome, C.D., and Silberling, N.J., 1989a,
Reinterpretation of lower Mesozoic rocks on the Chilkat Peninsula,
Alaska, as a displaced fragment of Wrangellia: Geology, v. 17, p. 3-6.

Plafker, George, Nokleberg, W.J., and Lull, J.S., 1989b, Bedrock geology
and tectonic evolution of the Wrangellia, Peninsular, and Chugach
terranes along the Trans-Alaskan Crustal Transect in the northern
Chugach Mountains and southern Copper River basin, Alaska: Journal of
Geophysical Research, p. 4255-4295.

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

Richards, M.A., Jones, D.L., Duncan, T.A., and DePaolo, D.J., 1991, A
mantle plume initiation model for the formation of Wrangellia and others
oceanic flood basalt plateaus, Science, v. 254, p. 263-267.

Richter, D.H., 1976, Geologic map of the Nabesna quadrangle, Alaska:
U.S. Geological Survey Miscellaneous Investigations Map Series I-932,
scale 1:250,000.

Richter, D.H., Lanphere, M.A., and Matson, N.A., Jr., 1975, Granitic
plutonism and metamorphism, eastern Alaska Range, Alaska: Geological
Society of America Bulletin, v. 86. p. 819-829.

Riehle, J.R., Brew, D.A., and Lanphere, M.A., 1989, Geologic map of the
Mount Edgecumbe volcanic field, Kruzof Island, southeastern Alaska: U.S.
Geological Survey Miscellaneous Field Investigations Map I-1983, scale
1:63,360.

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 the Mesozoic tectonic history of the Border Ranges
fault system: Geological Society of America Bulletin, v. 101, p.
1021-1037.

Rubin, C.M., and Saleeby, J.B., 1991, Tectonic framework of the upper
Paleozoic and lower Mesozoic Alava sequence: a revised view of the
polygenetic Taku terrane in southern southeast Alaska: Canadian Journal
of Earth Sciences, v. 28, p.881-893.

Sainsbury, C.L., 1969, Geology and ore deposits of the central York
Mountains, western Seward Peninsula, Alaska: U.S. Geological Survey
Bulletin 1287, 101 p.

Saleeby, J.B., and Rubin, C.M., 1990, The East Behm Canal gneiss complex
(southern southeast Alaska) and some insights into basement tectonics
along the Insular suture belt \[abs.\]: Geological Association of
Canada, Program with Abstracts, v. 15, p. A116.

Samson, S.D., Patchett, P.J., McClelland, W.C., and Gehrels, G.E., 1991,
Nd and Sr isotopic constraints on the petrogenesis of the west side of
the northern Coast Mountains batholith, Alaska and Canadian Cordillera:
Canadian Journal of Earth Sciences, v. 28, p. 939-946.

Silberling, N.J., Richter, D.H., Jones, D.L., and Coney, P.C., 1981,
Geologic map of the bedrock part of the Healy A-1 quadrangle south of
the Talkeetna-Broxson Gulch fault system, Clearwater Mountains, Alaska:
U.S. Geological Survey Open-File Report 81-1288, scale 1:63,360.

Silberling, N.J., Jones, D.L., Monger, J.W.H., and Coney, P.J., 1992,
Lithotectonic terrane map of the North American Cordillera: U.S.
Geological Survey Miscellaneous Investigations Series Map I-2176, 2
sheets, scale 1:5,000,000.

Sisson, V.B., Hollister, L.S., and Onstott, T.C., 1989, Petrologic and
age constraints on the origin of a low-pressure/high-temperature
metamorphic complex, southern Alaska: Journal of Geophysical Research,
v. 94, p. 4392-4410.

Smith, T.E., 1981, Geology of the Clearwater Mountains, south-central
Alaska: Alaska Division of Geological and Geophysical Surveys Geologic
Report 60, 72 p., 1 sheet, scale 1:63,360.

Souther, J.G., 1971, Geology and mineral deposits of Tulsequah map area,
British Columbia, Geological Survey of Canada Memoir 362, 45 p.

Stanley, W.D., Labson, V.F., Nokleberg, W.J., Csejtey, BŽla, Jr., and
Fisher, M.A., 1990, The Denali fault system and Alaska Range of Alaska:
Evidence for suturing and thin-skinned tectonics from magnetotellurics:
Geological Society of America Bulletin, v. 102, p. 160-173.

Tailleur, I.L., Mayfield, C.F., and Ellersieck, I.F., 1977, Late
Paleozoic sedimentary sequence, southwestern Brooks Range, *in* Blean,
K.M., ed., The United States Geological Survey in Alaska:
Accomplishments during 1976: U.S.G.S. Circular 751-B, p. B25-B27.

Till, A.B., Schmidt, J.M., and Nelson, S.W., 1988, Thrust involvement of
metamorphic rocks, southwestern Brooks Range, Alaska:Geology, v. 10, p.
930-933.

Turner, D.L., Forbes, R.B., Aleinikoff, J.N., Hedge, C.E., and
McDougall, I., 1983, Geochronology of the Kilbuck terrane in
southwestern Alaska \[abs.\]: Geological Society of America Abstracts
with Programs, v. 15., p. 407.

Turner, D.L., Herreid, Gordon, and Bundtzen, T.K., 1977, Geochronogy of
southern Prince of Wales Island: Alaska Division of Geological and
Geophysical Surveys Report 55, p. 11-20.

Tysdal, R.G., and Case, J.E., 1979, Geologic map of the Seward and
Blying Sound quadrangles, Alaska: U.S. Geological Survey Miscellaneous
Investigations Map Series I-1150, scale 1:250,000.

Wallace, W.K., Hanks, C.L., and Rogers, J.F., 1989, The southern
Kahiltna terrane: Implications for the tectonic evolution of
southwestern Alaska: Geological Society of America Bulletin, v. 101, p.
1389-1407.

Weber, F.R., McCammon, R.B., Rinehart, C.D., Light, T.D., and Wheeler,
K.L., 1988, Geology and mineral resources of the White Mountains
National Recreation area, east-central Alaska:U.S. Geological Survey
Open-File Report 88-284, 234 p., 23 plates.

Weber, F.R., Smith, T.E., Hall, M.H., and Forbes, R.B., 1985, Geologic
guide to the Fairbanks-Livengood area, east-central Alaska:Alaska
Geological Society, Anchorage, Alaska, 45 p.

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, 1 sheet, scale 1:250,000, 20
p.

Wheeler, J.O., and McFeeley, P., 1991, Tectonic assemblage map of the
Canadian Cordillera and adjacent parts of the United States of America:
Geological Survey of Canada Map 1712A, 3 sheets, scale 1:2,000,000.

Wirth, K.R., Harding, D.J., Blythe, A.E., and Bird, J.M., 1986, Brooks
Range ophiolite crystallization and emplacement ages from 40Ar/39Ar data
\[abs.\]: Geological Society of America Abstracts with Programs, v. 18,
p. 792.