Diagenesis and Stratigraphy of the 

Lisburne Group Limestones of the 

Sadlerochit Mountains and Adjacent 

Areas, Northeastern Alaska 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 857 

DIAGENESIS AND STRATIGRAPHY 

OF THE LISBURNE GROUP LIMESTONES 

OF THE SADLEROCHIT MOUNTAINS AND 

ADJACENT AREAS, NORTHEASTERN ALASKA 
Rhombs of dolomite set in sparry calcite. The red-stained zones parallel to the original rhomb faces are calcite (dedolomite). Overgrowths of 

homogeneous dolomite occur in two stages parallel to the lines of intersection of the rhomb faces. Patches of hematite (black) developed 

at the edge of the original rhomb and are included within the overgrowth; others developed on the outer edge of the overgrowths. Planepolarized light. Stained by Alizarin Red S. 
Diagenesis and Stratigraphy of the 

Lisburne Group Limestones of the 

Sadlerochit Mountains and Adjacent 

Areas, Northeastern Alaska 

By GEORGE V. WOOD and AUGUSTUS K. ARMSTRONG 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 857 

Biostratigraphy and depositional environments 

of the Lisburne Group, with a detailed account 

of the relative age of diagenetic events 

affecting the carbonate rocks and an 

analysis of the resultant mineralogical changes 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON 1975 
UNITED STATES DEPARTMENT OF THE INTERIOR 

ROGERS C. B. MORTON, Secretary 

GEOLOGICAL SURVEY 

V. E. McKelvey, Director 

Library of Congress Cataloging in Publication Data 

Wood, George V. 

Diagenesis and stratigraphy of the Lisburne Group limestones of the Sadlerochit Mountains and adjacent areas, northeastern 

Alaska. 

(Geological Survey Professional Paper 857) 

Bibliography: p. 38. 

Includes index. 

Supt. of Docs. No.: I 19.16:857 

1. Limestone-Alaska-Sadlerochit Mountains. 2. Diagenesis-Alaska-Sadlerochit Mountains. 3. Geology, StratigraphicCarboniferous. 4. Geology-Alaska-Sadlerochit Mountains. I. Armstrong, Augustus K.,joint author. II. Title. III. 

United States. Geological Survey. Professional Paper 85 7. 

QE471.15.L5W66 552'.5 74-26965 

For sale by the Superintendent of Documents, U.S. Government Printing Office 

Washington, D.C. 20402- Price $2.25 (paper cover) 

Stock Number 024-001-02658-9 

Catalog Number 119.16:857 
CONTENTS 

1\bstract _________________________________________________ _ 

Introduction ----------------------------------------------

Previouswork -------------------------------------------- 1\cknowledgments _______________________________________ _ 

Study method --------------------------------------------

Description of sections ------------------------------------

701\-4/5, Plunge Creek --------------------------------

691\-1, western Sadlerochit Mountains _________________ _ 

681\-4N4B, Sunset Pass, eastern Sadlerochit Mountains _ 

691\-4/4K, Old Man Creek ----------------------------

Environments of deposition --------------------------------

Biostratigraphic correlation _______________________________ _ 

Regional relations of Carboniferous carbonate rocks in the Sadlerochit Mountains _____________________________________ _ 

Graphic registry of stratigraphic sections ___________________ _ 

Diagenesis ------------------------------------------------ Calcite _______________________________________________ _ 

Grains ___________________________________________ _ 

Crinoids --------------------------------------

Bryozoa -------------------------------------- Other bioclastic debris _______________________ _ 

Ooliles _______________________________________ _ 

Origin of the oolite fabric _________________ _ 

Cementation of oolites ___________________ _ 

Mechanism of oolite formation _____________ _ 

Pellets _______________________________________ _ 

Cement ------------------------------------------ Sparry calcite cement _________________________ _ 

Neomorphic processes _________________________ _ 

Matrix ___________________________________________ _ 

Dolomite _____________________________________________ _ 

Dolomite _________________________________________ _ 

Origin of dolomites --------------------------------

Zoning in macrodolomites _________________________ _ 

Dedolomite _______________________________________ _ 

Page 

1 

1 

1 

2 

2 

3 

3 

6 

8 

9 

10 

12 

14 

15 

15 

16 

17 

17 

18 

18 

19 

19 

19 

20 

20 

20 

21 

22 

22 

22 

23 

23 

24 

25 

Diagenesis-Continued 

Dolomite-Continued 

Page 

Causes of dedolomitization ________________________ 25 

Distribution of iron------------------------------------ 26 

Fe2+ in calcite ------------------------------------ 26 

Fe2 + in dolomite ---------------------------------- 27 

Environmental significance ________________________ 27 

Chert ------------------------------------------------ 28 

Fabric ________________________________ ---· _ _ _ _ __ _ _ _ 28 

Matrix chert ---------------------------------- 28 

Intragranular chert---------------------------- 28 

Time of origin ------------------------------------ 29 

Mode of origin ------------------------------------ 29 

Source of silica ------------------------------------ 29 

Dolomite in chert---------------------------------- 30 

Sulfates ---------------------------------------------- 31 

1\nhydrite _________ _ __ ___ _ _ ______ _ ______ ____ __ ____ 31 

Description____________________________________ 31 

Interpretation -------------------------------- 31 

Celestite _ ____ _ ____ _______ ____ __ _ _____ _ _____ _ _____ _ 31 

Description____________________________________ 31 

Interpretation -------------------------------- 32 

Barite -------------------------------------------- 32 

Marble________________________________________________ 32 

Pure calcite marbles ------------------------------ 32 

Western Sadlerochit Mountains section ________ 32 

Old Man Creek section ------------------------ 33 

Mode of origin -------------------------------- 33 

Dolomites associated with marble __________________ 35 

Description____________________________________ 35 

Mode of origin -------------------------------- 35 

Relative ages of formation of diagenetic features ________ 36 

Selected bibliography -------------------------------------- 38 

Index ---------------------------------------------------- 43 

ILLUSTRATIONS 

[Plates follow index] 

FRONTISPIECE. Photomicrograph of dolomite rhombs set in sparry calcite. 

PLATES 1. Oolite bioclastic grainstone, oolitic grainstones, oolitic packstone/grainstone, bioclastic grainstone, and bryozoan 

crinoid grainstones. 

2. Bryozoan grainstones, dolomitic bryozoan grainstones, microdolomite, bioclastic microdolomite, dolomitic crinoid bryozoan packstone, and dolomitic bryozoan packstone. 

3. Bioclastic grainstone, macrodolomite, microdolomite, microdolomite with clot of iron oxide. 

4. Macrodolomite, iron-rich dolomite, dolomitic bioclastic grainstone, dedolomite, early dolomite. 

5. Dedolomite with annotated diagram. 

v 
VI 

PLATES 6. 

7. 

8. 

9. 

10. 

11. 

12. 

CONTENTS 

Bioclastic mudstone, pellet intraclast grainstone, sheared limestone, shear fabric, marble. 

Sequence of diagenetic events. 

Chert, siliceous lime-mudstone, microdolomite, bryozoan crinoid packstone/grainstone, calcareous chert, matrix chert, 

chert. 

Bioclastic wackestone, crinoid bryozoan grainstone, bioclastic microdolomite, bryozoan crinoid packstone, bioclastic 

packstone, dedolomite, bioclastic grainstone. 

Chert/dolomite, "Osagia" grainstone, argillaceous limestone. 

Barite, celestite, macrodolomite, anhydrite, laminated dolomite. 

Stylolites, bioclastic packstone, fractures, bryozoan grainstone, argillaceous wackestone. 

FIGURES 1. 

Page 

Index map of arctic Alaska showing location of Carboniferous outcrops and study area ----------------------------- 2 

TABLE 

2. Correlation diagram for the Lisburne Group in the Sadlerochit Mountains and adjacent areas _____________________ 4 

3--6. Photographs of: 

3. Alapah Limestone, Plunge Creek Sections 70A-4/5 ------------------------------------------------------- 6 

4. Wahoo Limestone and Sadlerochit Formation, Plunge Creek sections 70A-4/5_______________________________ 7 

5. Western Sadlerochit Mountains section 69A-1 ----------------------------------------------------------- 8 

6. Lisburne Group outcrop east of eastern Sadlerochit Mountains sections 68A-4A/4B ------------------------- 9 

7. Generalized cross section showing depositional environments of the Lisburne Group ______________ ----------------- 11 

8. Idealized graphs showing variation of depositional environments in the four stratigraphic sections·------------------ 12 

9. Regional correlation chart for the Lisburne Group of arctic Alaska ----------------------------------------------- 13 

Lithofacies map of northeastern Alaska at the end of Meramecian time ------------------------------------------- 14 

Lithofacies map of northeastern Alaska near the end of Chesterian time ----------------------------------------- 14 

10. 

11. 

12. 

13--16. 

17. 

18--24. 

25. 

Idealized cross section from west end of Sadlerochit Mountains to junction ofMarsh Fork and Canning River ___________ 15 

Location maps of: 

13. Plunge Creek sections 70A-4 and 70A-5 ------------------------------------------------ _________________ 16 

14. Western Sadlerochit Mountains section 69A-1 _ __ _____ ____ _____ ______ ____ _ ____ _____ _ ____ __ ___ _ ______ __ _ __ 16 

15. Eastern Sadlerochit Mountains sections 68A-4A and 68A-4B --------------------------------------------- 17 

16. Old Man Creek sections 69A-4 and 69A-4K ------------------------------------------------------------- 17 

Sketches showing probable sequence of alteration of aragonite bioclast debris -------------------------------------

Diagrams showing: 

18. Alteration from tangentially arranged aragonite crystals to radially arranged calcite crystals within the con18 

centric mucilaginous layers of an oolite-------------------------------------------------------------- 19 

19. Sequence of diagenesis in zoned iron-rich dolomites------------------------------------------------------- 25 

20. Diagenetic history of limestones containing intragranular chert ------------------------------------------- 28 

21. Stratigraphic distribution of metamorphic fabrics in dynamically recrystallized limestones, western Sadlerochit 

Mountains section 69A-1 _ _ __ _ _ _ _ _ __ _ _ ___ _ _ ___ _ _ _ _ _ _ _ _ _ __ _ _ __ __ _ _ __ _ _ __ _ _ _ _ __ _ _ __ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ __ _ 33 

22. Generalized sequence of dynamic metamorphism in limestones of the Lisburne Group----------------------- 34 

23. Sequence of dynamic metamorphism in limestones of the Lisburne Group --------------------------------- 34 

24. Sequence of crystallization in marble of section 69A-1 --------------------------------------------------- 35 

Graph showing possible stress-strain relation of calcite and dolomite --------------------------------------------- 36 

TABLES 

Page 

1. Classification of carbonate rocks according to depositional texture_________________________________________________ 3 

2. Percentage of major rock types in the Lisburne Group in three sections ------------------------------------------- 3 

3. Habit and iron content of sparry calcite cement and dolomite----------------------------------------------------- 27 
DIAGENESIS AND STRATIGRAPHY OF 

THE LISBURNE GROUP LIMESTONES OF THE 

SADLEROCHIT MOUNTAINS AND ADJACENT AREAS, 

NORTHEASTERN ALASKA 

By GEORGE V. Woon1 and AuGusTus K. ARMSTRONG 

ABSTRACT 

Four complete sections of the Mississippian and Pennsylvanian · 

limestones of the Lisburne Group in or adjacent to the Sadlerochit 

Mountains were sampled at 5- to 10-foot intervals for petrographic 

study. The Sadlerochit Mountains are shown to have been a landmass 

during Meramecian time and to have been subsequently submerged 

during the Chesterian transgression (Zone 16). Regional transgressions also occurred during Meramecian time (Zone 13) and at the 

beginning of Pennsylvanian (Zone 20) time. 

The Alapah Limestone (Mississippian) has a dominantly lime-mud 

matrix and in many places is dolomitized toward the top, whereas the 

Wahoo Limestone (Pennsylvanian) is dominantly a grainstone facies 

with intergranular sparry calcite. The grains of the limestones are 

mostly crinoids, bryozoans, and pelecypods, together with pellets and 

oolites. The depositional environment ranged from supratidal to subtidal. The genesis of the oolite grains is discussed in particular detail, 

and it is concluded from recent work on the amino acid content that 

biochemical elements have a large influence on their origin. 

Two phases of sparry calcite cementation occurred in the grainstone 

facies; the first phase is a fringe around the clasts and is free of iron, 

and the second phase fills the remaining intergranular spaces and is 

commonly rich in iron. The dolomites are considered to be of early 

diagenetic origin. The coarse dolomite rhombs that occur as accessories in the grainstones are rich in iron and tend to be zoned. These 

rhombs are prone to dedolomitization. The dedolomitization process is 

not of recent origin, as demonstrated by postdedolomitization overgrowths of iron-free dolomite. It is more likely to have occurred during 

a period of emergence during Chesterian time. 

Two types of chert are distinguished: "matrix" chert and intragranular chert. The "matrix" chert is considered to be of direct biogenic 

origin. The intragranular chert, usually restricted to the grainstone 

facies, formed within pelecypod shells or crinoid plates by the reaction 

of silica in the sea water with the organic tissue in the bioclast to form 

a short-lived organosilicic acid. This acid, in turn, reacted with the 

calcite of the bioclast to precipitate silica on a piecemeal basis. 

Anhydrite, celestite, and barite have been identified in the Lisburne Group limestones ofthe subsurface, and their association with 

algal mats suggests that sabkha-type sedimentation of the presentday Arabian Gulf is a depositional model for these beds. Marble 

interbedded with unaltered sedimentary limestones in the western 

Sadlerochit Mountains is considered to be a product of dynamic 

metamorphism restricted to the sole of a major thrust plate. 

1British Petroleum Co., Ltd., BP Research Centre, Chertsey Road, Sunbury-on-Thames, 

Middlesex, England. 

The fabrics common in the limestones of the Old Man Creek section 

are attributed to thermal alteration related to the intrusion of the 

Mount Michelson pluton; the pluton, in turn, suggests that the granite 

is post-Pennsylvanian in age. 

Diagenetic modification of the Lisburne Group limestones was 

nearly complete before the marbles, stylolites, and calcite-filled fractures formed. The rock fabrics remain virtually the same today. 

INTRODUCTION 

The four outcrop sections of carbonate rocks from the 

Sadlerochit Mountains and adjacent areas of the northeastern Brooks Range (fig. 1) 1

represent most of the 

typical rock types and environments of deposition of the 

Lisburne Group. We believe a study of the history of 

sedimentation and diagenetic processes of these sections will be applicable to most other outcrops of the 

Lisburne Group in the Brooks Range and in the subsurface of the North Slope. A detailed study of the sedimentation and diagenesis gives one insight into the complex 

geologic history of the Lisburne Group and facilitates 

the construction of lithofacies maps. The knowledge 

gained from this study is readily applicable in helping 

to predict the porosity trends in the Lisburne Group of 

the subsurface. 

PREVIOUS WORK 

Schrader (1902) was the first to apply the name Lisburne Formation to the carbonate rocks at Anaktuvuk 

River valley, which were incorrectly dated as Devonian. 

Later studies (Collier, 1906, p. 22-26) revealed the 

limestones to be Mississippian in age. In the Shainin 

Lake area (fig. 1), Bowsher and Dutro (1957, p. 3, 4, 6) 

recognized two new formations within the Lisburne, 

which they raised to group rank. The lower formation, 

the Wachsmuth Limestone, is divided into four informal members and overlies the Kayak Shale. The upper 

formation, Alapah Limestone, overlies the Wachsmuth 

Limestone and has nine informal members. The Alapah 

Limestone at its type locality is covered by Pleistocene 

glacial gravel and alluvium. 

1 
2 DIAGENESIS AND STRATIGRAPHY OF THE LISBURNE GROUP LIMESTONES, NORTHEASTERN ALASKA 

170° 168° 166° 164° 162° 

I 1' c 

A R 70° 

160° 158° 156° 

c 

NAVAL PETROLEUM RESERVE 

NUMBER 4 

50 0 

154° 152° 

50 100 

150° 148° 146° 144° 142° 140° 138° 

0 EXPLANATION 

c e 4. 0 

N Outcrop of Carboniferous 

rocks 

-1- Prudhoe Test well 

150 MILES 

50 0 50 100 50 KILOMETRES 

FIGURE 1.-Map of arctic Alaska showing location of the area studied, outcrop pattern of Carboniferous rocks, and significant oil exploration 

stratigraphic test wells. 

Brosge, Dutro, Mangus, and Reiser (1962) described 

the Paleozoic sequence in the eastern Brooks Range. In 

this region they recognized three formations within the 

Lisburne Group: the Wachsmuth and Alapah Limestones and an overlying limestone that they named the 

Wahoo Limestone. They assigned the Wahoo a Pennsylvanian(?) and Permian age. 

Armstrong, Mamet, and Dutro (1970) and Mamet and 

Armstrong (1972) reported the Lisburne Group within 

the area of this study to be of Late Mississippian to 

Middle Pennsylvanian (Atokan) age. The age assignments are based on microfossil assemblages. The coral 

fauna, biostratigraphy, and paleoecology of the Wahoo 

Limestone in the Sadlerochit Mountains was described 

by Armstrong (1973). 

Petrographic studies of the carbonate rocks of the 

Lisburne in the Endicott Mountains, central Brooks 

Range, were made by Krynine, Folk, and Rosenfeld 

(1950) for the dolomites and Krynine and Folk (1950) 

for the limestones. Armstrong (1970b) published a short 

report on the petrography of Mississippian chert and 

dolomites from the Lisburne Group in the Killik 

River-Mount Bupto Region, Brooks Range. 

ACKNOWLEDGMENTS 

The fieldwork for this study was done by Armstrong. 

We wish to express our appreciation to I. L. Tailleur, the 

party chief, summer of 1968, and H. N. Reiser, the party 

chief, summers of 1969 and-1970, for their generosity in 

supporting the stratigraphic studies. We also thank the 

Naval Arctic Research Laboratory (Barrow), Office of 

Naval Research, for their logistical support of fieldwork 

in the summers of 1968, 1969, and 1970. 

George Wood is responsible for the petrographic work 

and diagenetic history. We thank the Chairman of the 

British Petroleum Co., Ltd., for permission to carry out 

this study and to publish its conclusions. Dr. P. E. Kent, 

F.R.S., Assistant General Manager, Exploration, and 

Wood's colleagues at the British Petroleum Research 

Centre have given considerable encouragement to the 

work. Dr. R. Walls and Mrs. E. Aston, in particular, are 

thanked for their help in interpreting the metamorphic 

fabrics. Professor B. L. Mamet of the Universite de 

Montreal determined the foraminiferal zones in the 

stratigraphic sections. 

STUDY METHOD 

This study is based on measured stratigraphic sections from which lithologic and foraminiferal samples 

were collected at intervals of 5-10 feet. Thin sections 

were cut from the samples to determine the microfossil 

assemblages and the carbonate petrography and microfacies. Dr. B. L. Mamet identified the microfossils, 

and his microfossil zones are the basis for the regional 

stratigraphic correlations in this study. Detailed 

documentation of the microfossil zones used in the 
DESCRIPI'ION OF SECTIONS 3 

stratigraphic section of this report can be found in Armstrong, Mamet, and Dutro (1970) and Mamet and Armstrong (1972). 

The carbonate rock classification used in this report is 

that of Dunham (1962) (table 1). The lithologic and 

paleontologic symbols used in this report are shown in 

figure 2. 

DESCRIPTION OF SECTIONS 

The four sections described in detail in this paper (fig. 

2), Plunge Creek, 70A-4/5; western Sadlerochit Mountains, 69A-1; eastern Sadlerochit Mountains, 

68A-4A/4B; and Old Man Creek, 69A-4/4K, were sampled at 5- to 10-foot intervals. The detailed petrography, 

largely done by Wood, is based on thin-section study of 

these samples and is integrated with the field descriptions by Armstrong. The overall percentage of major 

rock types in three of the sections is given in table 2; the 

Old Man Creek section has been omitted because 

sporadic intense recrystallization has obliterated a 

large part of the original fabric. 

In general, there is a progressive west-east increase 

in the proportion of grainstone, and a related west-east 

decrease in the proportion of mud-supported carbonates 

(that is, wackestone and mudstone). The proportion of 

dolomite has a strong maximum in the Plunge Creek 

section, but it must be pointed out that the proportion of 

dolomite in Old Man Creek (42 percent) is even higher. 

Between 14 and 20 percent of the limestone in the three 

sections is dolomitic. 

The sections are subdivided into units on the basis of 

their dominant lithologic characters, but some of the 

subdivisions are rather arbitrary because of the mixing 

of rock types. The depths referred to are those of the 

total thickness of the Lisburne Group taken from the 

base of the section and recorded on the right of the 

stratigraphic columns in figure 2. 

TABLE 2.--Percentage of major rock types in the Lisburne Group in 

three sections 

Rock type 

Grainstone _______________ _ Packstone _________________ _ 

Wackestone/mudstone _____ _ Dolomite _________________ _ 

70A-4/5 Plunge Creek section1 

21 

26 

12 

33 

17 percent is chert. 15 percent of limestone is dolomitic. 2 15 percent of limestGne is dolomitic. 3 14 percent of limestone is dolomitic. 

69A-1 

Western 

Sadlerochit 

Mountains 

section2 

47 

33 

11 

9 

70A-4/5, PLUNGE CREEK 

68A-4A/4B 

Eastern 

Sadlerochit 

Mountains 

section3 

55 

24 

6 

15 

The base of the Lisburne Group in the Plunge Creek 

section is taken arbitrarily where the carbonate content 

becomes dominant over the shale of the underlying 

Kayak(?) Shale. The Kayak(?) Shale is 1,290 feet thick 

and it rests on 30 feet of the Kekiktuk Conglomerate, 

which in turn rests unconformably on tilted Neruokpuk 

Formation. 

The basal unit (0-330 ft) of the Lisburne Group in this 

section is argillaceous and dolomitic wackestone and 

mudstone. The rock represents a continuation of the 

quiet open-water marine sedimentation that persisted 

during the deposition of the Kayak(?) Shale but differs 

by being dominated by carbonate. Foraminifera and 

finely comminuted crinoid debris are the dominant 

faunal elements. The interrhombic spaces in the macrodolomites that commonly occur within this unit are 

filled with dark clay minerals, the residue after completion of the dolomitization process. From 330 to 720 feet 

is a homogeneous unit composed mostly of macrodolomite in which the rhombs are larger than 50 micrometres. 

In the interval 550-558 feet, which may be correlative with the interval 50-65 feet in the western Sadlerochit Mountains section (69A-1), the dolomite 

TABLE !.-Classification of carbonate rocks according to depositional texture (Dunham, 1962, p. 117) 

Depositional texture recognizable Depositional texture 

Original components not bound together during deposition 

not recognizable 

Original components 

Contains mud Lacks mud were bound together Crystalline carbonate 

during deposition*** (particles of clay and fine silt size) and is as shown by intergrown 

grain- skeletal matter, 

Mud-supported Grain-supported supported lamination contrary to 

Less than More than gravity, or sediment10 percent 10 percent 

floored cavities that (Subdivide according are roofed over by to classifications grains grains organic or questionably designed to bear on organic matter and physical texture or are too large to be diagenesis.) 

interstices. 

Mudstone Wackestone Packstone Grainstone Boundstone 
4 DIAGENESIS AND STRATIGRAPHY OF THE LISBURNE GROUP LIMESTONES, NORTHEASTERN ALASKA 

T. 

4 

N. 

T. 

1 

N. 

T. 

1 

s. 

T. 

3 

SHUBLIK 

MOUNTAINS 

MOUNTAINS 

+Mount 

Chamberlin 

ww 

NM 

MM 

a: a: 

Mount 

Michelson 

..<fo-1?. 

~1{1~ 0~ 

tf.t)'.s s.L__L ______ _L_L~~L_~_L ________ u_ ________ ~--~----~--------~----L_ __ J_ ________ J_ ____ ~ 

5 0 5 10MILES 

5 0 5 10 KILOMETRES 

FIGURE 2.-Correlation diagram for the Lisburne Group in the Sadlerochit Mountains and adjacent areas. Biostratigraphic zonation 

is based on the microfossil zones of B. L. Mamet. Index map showing location of the stratigraphic sections and symbols used for 

fossils and lithology is shown on the lower part of this diagram. The cross section for 70A-2 and 70A-3 is in figure 12. 

rhombs are etched and partly replaced by sparry calcite 

( dedolomitized). 

From 720 to 918 feet (fig. 3) is a sequence of diverse 

rock types ranging from crinoid bryozoan grainstone to 

packstone with intervals ofmacrodolomite. Pellets and 

oolites also occur sporadically. The depositional environment probably was marginal between the area of 

shoal-carbonate deposition and the open platform. The 

intervals ofmacrodolomite contain evidence of two generations of dolomite formation. The zoned first-phase 

dolomites, sometimes in rich iron, are crosscut both by 

iron-poor second-phase dolomite and by sparry calcite 

cement. 

Above 918 feet is a unit of dolomitic wackestone and 

packstone with crinoid and bryozoan debris (to 1,190 ft). 

Macrodolomite is predominant over the basal 50 feet. 

Matrix chert is common, particularly in the upper 65 

feet. The chert contains as much as 40 percent of macroand micro-dolomite, often with individual rhombs intensely corroded. The presence of ghosts after sponge 

spicules suggests that the chert is of direct biogenic 

origin. 

In the intervall,l90-1,630 feet macrodolomite is the 

dominant rock type and is regularly intercalated with 

dolomitic bryozoan crinoid wackestone and packstone. 

Except for the change in the relative abundance of mac-
DESCRIJYI'ION OF SECTIONS 

Formation 

COMPOSITION, IN PERCENT 

0 10 50 90 100 Dolomite 

100 90 50 

FIGURE 2.-Continued. 

10 0 Limestone 

Sandstone Nodular 

chen 

5 

SYMBOLS FOR 

FOSSIL PARTICLES 

AA Algal mats 

# ' Calca<eous 

algae 

& SmaJ"" Foraminifera 

-<57 Fusulinids 

0 Corals 

T Bryozoans 

7 Brachiopods 

* Echinoderms 

= Ostracodes 
6 DIAGENESIS AND STRATIGRAPHY OF THE LISBURNE GROUP LIMESTONES, NORTHEASTERN ALASKA 

FIGURE 3.-Alapah Limestone at Plunge Creek sections 70A-4/5. Line of traverse shown by arrows along crest of ridge. 

rodolomite, this interval is markedly similar to the 

lower unit (918-1,190 ft). Matrix chert is again common 

with microdolomite rhombs and ghosts after sponge 

spicules. Dolomite rhombs in the macrodolomite are 

commonly outlined by iron oxide. Crinoid debris in 

these rocks commonly has bent twin planes suggesting 

at least two phases of earth movement. 

From 1,630 to 1,880 feet the rock is uniform bryozoan 

crinoid packstone containing as much as 30 percent 

intergranular dolomite in the carbonate mud. The 

upper 55 feet is macrodolomite with remains of 

bryozoan debris still preserved in calcite. The depositional environment of this unit was probably an openwater platform beyond the zone of water agitation, but 

the occurrence at 1,880 feet of polycrystalline quartz 

preserved with the external morphology of an anhydrite 

nodule suggests that the macrodolomite in the interval 

1,825-1,880 feet may have been deposited in an 

intratidal/supratidal environment. 

Above 1,800 feet (fig. 4), and persisting to the top of 

the section at 2,505 feet, is a homogeneous unit of grainstone in which all the intergranular space is occupied by 

sparry calcite cement. 

Coarse-grained bryozoan and crinoid debris is the 

dominant clastic element, but sporadic intervals of oolites or pellets also occur. Intragranular chert is commonly nucleated within crinoid plates, in contrast to the 

dominant matrix chert in the interval 918-1,630 feet. 

The depositional environment of this unit was probably 

shoals of bioclastic debris from which all available carbonate mud had been winnowed. 

69A- l, WESTERN SADLEROCHIT MOUNTAINS 

The lowermost 50 feet of this section, which consists 

of shales with limestone lenses, has been questionably 

assigned to the Kayak Shale unconformably overlying 

the tilted Katakturuk Dolomite of Devonian or older 

age. 

The lowermost limestone unit (0--65 ft), which consists of wackestone and packstone with fine-grained 

bioclastic debris dominated by crinoids, appears to be a 

continuation ofthe sedimentary pattern of the Kayak(?) 

Shale but with an almost total absence of clay minerals. 

The upper part of this unit is characterized by extensive early dedolomitization that may be evidence of 

emergence; this is discussed in detail in the section on 

diagenesis. From 65 to 4 70 feet the rock is largely 

sporadically dolomitized, medium-grained, bryozoan, 

crinoid, and pellet grainstone with scattered oolitic 

layers. The rock types reflect a shallowing of the water, 

suggesting that water agitation was sufficient to remove the bulk of the available carbonate mud to a 

quieter area. The environment was probably a shallow 

marine shelf with clumps of bryozoans and crinoids. 

Abundant fecal pellets suggest that the patches of car-
DESCRIPTION OF SECTIONS 7 

F IGURE 4.-Plunge Creek section 70A-4/5. Footage is marked, as is the contact with the overlying Sadlerochit Formation. Photograph 

taken from helicopter; view north. 

bonate mud were subject to considerable bioturbation. 

The overlying rocks (470-770 ft) are dominantly pellet 

bryozoan packstone with scattered thin dolomite beds; 

three intervals contain as much as 20 percent 

fine-grained quartz. The dolomite rhombs, as at 593 

feet, commonly have an iron-rich core and an iron-free 

rim outlined in iron oxide. These rocks suggest a 

gradual reduction in the intensity of wave agitation, 

probably in an environment protected from waves with 

restricted access to open water and with intense bioturbation. 

From 770 to 1,070 feet wackestones become more 

abundant, although packstones are still common. 

Bryozoan debris and pellets are the dominant grains. 

There are sporadic dolomites, and a large proportion of 

the intergranular carbonate mud contains dolomite 

rhombs that are commonly outlined by iron oxides. In 

the lower part of this interval, the original dolomite 

rhomb outlines are preserved, but the centers are commonly void. This interval represents a continuation of 

the protected environment suggested for the unit at 

4 70--770 feet but with an increase in salinity. 

At 1,070 feet there is a major change in rock type. 

Mineralogically, the rock is still calcite, but the original 

texture and nature of the grains have been obliterated 

by extensive metamorphic recrystallization that produced interpenetrating crystals. This rock must be referred to as marble and is almost certainly a product of 

metamorphism along a thrust plane at 1,140 feet in the 

section. This probable plane of dislocation coincides 

with the top of a marked break of slope, and the upper 

limit ofthe marble coincides with the suggested base of 

the Wahoo Limestone at 1,140 feet (fig. 5). The 

metamorphism is restricted to the sole of the postulated 

thrust with the intensity decreasing downward. It is not 

known how much of the original section is repeated or 

missing as a result of this suggested structural discontinuity. The details of the metamorphic fabrics are described in the section on "Diagenesis." 

The basal rocks (1, 140--1,325 ft) of the Wahoo Limestone are medium-grained bryozoan crinoid wackestone 

and packstones similar in type and depositional environment to the uppermost rocks of the Alapah Limestone (that is, from 770--1,070 ft), except that dolomite is 

almost totally absent. The uppermost rocks of the 

Wahoo Limestone are coarse-grained bryozoan crinoid 
8 DIAGENESIS AND STRATIGRAPHY OF THE LISBURNE GROUP LIMESTONES, NORTHEASTERN ALASKA 

FIGURE 5.-Section 69A- 1, western Sadlerochit Mountains, showing stratigraphic footages and contacts between Kayak(?) Shale, Alapah Limestone, Wahoo Limestone, and Sadlerochit Formation . Zone of metamorphic marble and thrust fault are also shown. 

View south. 

grainstones (1,325-1,450 ft) with a 45-foot-thick oolitic 

grainstone interval near the top of the section. This unit 

represents a strongly agitated open-shoal environment 

with banks of oolites. Any carbonate mud that may 

have been present has been winnowed from the place of 

deposition, and the debris is extremely well sorted. 

68A-4B, SUNSET PASS, 

EASTERN SADLEROCHIT MOUNTAINS 

The basal 7 feet of this section immediately overlying 

tilted shales and sandstones of the Neruokpuk Formation consists of very coarse angular grains of quartz and 

chert cemented by sparry calcite. Hematite-rich clay 

laminae and size grading emphasize the layering. 

These rocks grade upward into pellet crinoid grainstones (0-360 ft) with scattered layers of packstones and 

mudstone. Matrix chert (section on "Chert") is common. 

The fact that carbonate mud is scattered throughout the 

grainstone suggests that the dominant depositional environment was an open platform close to the lower limit 

of wave agitation. Above 360 feet (up to 820 ft) the 

dominant rock type is macrodolomite with an intermediate interval of partly dolomitic grainstone (fig. 6). 

Individual dolomite crystals are clear, anhedral, and 

commonly about 50 micrometres in size. Interrhombic 

chert and calcite are common. The preferential development of dolomite in fine-grained carbonate rock 

suggests that the original rock in this interval contained a high proportion of carbonate mud. Algal-mat 

sediments were recorded at 760 feet in this section by 

Armstrong and this fact suggests that the dominant 

environment was intertidal to supratidal (Wood and 

Wolfe, 1969). 

From 820 to 1,332 feet the dominant rock type is 

partly dolomitized fine- to medium-grained grainstone 

with subordinate packstones. Bryozoans and crinoids 

are the dominant clastic elements in the lower part of 

this unit, which contains pellets. in the upper 240 feet. 

At 1,130 feet, fine quartz grains are a common accessory. Intragranular chert developed within crinoid 

plates is common. The dominant environment is an 

open marine shelf with the pellets representing the 

products of bioturbation of carbonate mud. The base of 

this interval (820ft) is taken as the base of the Wahoo 
DESCRIPTION OF SECTIONS 9 

FIGURE 6.- 0utcrop of the Lisburne Group on hillside east and opposite the line of traverse of eastern Sadlerochit Mountains sections 

68A-4A/4B. Thin-bedded dolomite near the top of the Alapah Limestone forms the rubble-covered slope beneath the massive cliffs of 

Wahoo Limestone. The topographic expression of the Lisburne Group clearly reflects the different depositional environments in which the 

carbonate rocks formed. The Alapah Limestone is 830 fee t thick. 

Limestone. The second-stage sparry calcite cement (see 

section on "Sparry Calcite Cement") of this interval is 

very rich in iron. 

From 1,332 to 1,562 feet the rock is mostly oolitic 

grainstone with rare oolitic packstones. The individual 

oolites have well-developed cores of either bryozoan or 

crinoid debris with four to five thin oolitic layers. The 

oolites tend to be of medium to coarse sand E;ize and are 

well sorted. This rock type was probably deposited on an 

open-water marine bank, as shoals and dunes, in which 

intense water agitation was of sufficient strength to roll 

the bioclastic debris and allow concentric deposition of 

aragonite. The cores ofthese oolites range in shape from 

elongate to equidimensional, but it was obviously easier 

for oolite skins to develop on equidimensional cores. 

Elongate grains with oolitic skins can be considered an 

rhombs are edged with iron oxide. A slight modification 

of this oolitic horizon persists for 90 feet (1,562-1,652 

ft); the bioclastic debris tends to be coated by the crenulated encrusting algae Osagia rather than by oolitic 

layers. The depositional environment was probably 

very similar to that of the underlying oolitic grainstones (Henbest, 1968). 

From 1,652 to 1,692 feet at the top of the section the 

facies changes abruptly to pellet wackestone and packstone that is sporadically rich in both pyrite and sponge 

spicules. This rock type suggests a change in environment to a restricted platform protected from the main 

oceanic circulation. This kind of environment accounts 

for a high reduction potential. 

69A-4 /4K, OLD MAN CREEK 

index of extreme water agitation. The rare oolite pack- The Old Man Creek section is anomalous with regard 

stones probably resulted from incorporation of oolites of to both thickness and facies because of intense tectonic 

the banks into the adjacent and protected intershoal and probable thermal metamorphic effects. The section 

carbonate mud. Chert is commonly developed within j is only about 7 miles north of the Mount Michelson 

crinoid plates, and the rare intergranular dolomite · pluton of Mount Michelson. Sheared greenstones and 
10 DIAGENESIS AND STRATIGRAPHY OF THE LISBURNE GROUP LIMESTONES, NORTHEASTERN ALASKA 

pyroclastic rocks that crop out in Old Man Creek are 

considered (Reiser, 1970) to be pre-Mississippian in age. 

In the section on "Diagenesis," the case for a postPennsylvanian age of the Mount Michelson pluton is 

argued on the basis of the grain fabrics of the Lisburne 

Group in Old Man Creek, some of which are attributed 

to thermal metamorphic effects. The boundary between 

the Lisburne Group and the overlying Sadlerochit Formation is almost certainly a thrust fault as shown by 

the strongly sheared fabric (see pl. 6, figs. 3, 4). 

The basal 290 feet of the section, probably separated 

from the Neruokpuk Formation by a fault, has been 

assigned to the Kayak(?) Shale of the Endicott Group, 

but the basal 210 feet contains completely recrystallized marble with annealed fabrics, argillaceous 

laminae, and unaltered macrodolomites. If the argument for the thrust origin of the marble unit of section 

69A-1 (western Sadlerochit Mountains) holds, then this 

basal unit could well contain a series of thrust slices. 

The macrodolomites of this interval show no textural 

response to this suggested thrusting, but it is not necessary to postulate a posttectonic origin for the dolomite. 

As discussed in the section on "Marble," dolomite has a 

higher fracture point and greater ductility than calcite, 

which allows calcite to fracture (and anneal) while 

dolomite is still in the elastic field. 

From the base of the Lisburne Group to 125 feet 

microdolomite is the dominant rock type with intercalated intervals ofunfossiliferous lime mudstone . These 

rocks may represent syngenetic dolomitization of 

lagoonal carbonate muds. 

Above 125 feet to 830 feet is a mixed association of 

dolomitic pellet packstone and grainstone with a high 

proportion of interbedded macrodolomite. Commonly, 

the macrodolomite crystals (sometimes edged with iron 

oxide) are replaced by sparry calcite as a result of marginal corrosion and spotty replacement within the 

crystals. This partial dedolomitization is probably a 

response to thermal metamorphism; this type of 

metamorphism is also emphasized throughout this interval by intense interfingering of the grain margins in 

the limestones. 

From 830 to 930 feet is a thin interval ofnondolomitic 

fine-grained crinoid wackestone with scattered fine 

quartz grains. An open-marine platform is the most 

likely environment for this interval. 

From 940 to 1,032 feet is a homogeneous interval of 

microdolomite with several calcite-filled veinlets. 

These rocks are commonly layered as a result of ferruginous intergranular material that may represent 

original algal-mat laminations. 

Above 1,060 feet to the top of the section, the rock 

assigned to the Wahoo Limestone probably was dominantly an original crinoid grainstone. Grain twinning 

and interpenetration are ubiquitous and tend to obscure 

the original fabric. Dedolomitized rhombs edged with 

iron oxide are common. In scattered horizons the formation of annealed calcite, probably along minor thrust 

plane·s, has totally obliterated evidence of the original 

rock type. 

ENVIRONMENTS OF DEPOSITION 

Depositional environments of the Lisburne Group 

(fig. 7) ranged from an openwater platform to shallowwater lime-sand shoals to areas of open and restricted 

platform with gradual increase in salinity related to 

partial separation from open marine circulation. This 

sequence terminated with the intertidal-supratidal 

environment in which algal mats are a characteristic 

feature. The representation of figure 7 in no way 

characterizes a particular time interval. 

Figure 8 is an interpretation of the variation in depositional environment of the four stratigraphic sections 

described in the previous section. Decisions regarding 

the assignment of a particular rock type to a specific 

depositional environment were somewhat arbitrary, 

especially for the dolomites. If, for example, algal mats 

were observed in the field, an intertidal environment is 

inferred, but in the absence of other evidence, a restricted platform environment is indicated for dolomite 

units. The Alapah Limestone-Kayak(?) Shale boundary 

in section 70A-4/5 (Plunge Creek) occurs in Zone 13 of 

the Meramecian Series of the Upper Mississippian. The 

base of the two sections in the Sadlerochit Mountains is 

in Zone 16 (Chesterian Series); there it unconformably 

overlies Devonian or older rocks. Zone 14 is present in 

the Old Man Creek section. This variation in the nature 

and age of the base of the Alapah Limestone suggests 

that the Plunge Creek section lies in an area of constant 

downwarp, subsequent to the transgression of the 

Kayak(?) Shale which occurred probably during 

Meramecian time ( < Zone 13). This Meramecian transgression is also recorded in the Ikiakpuk section 

(68A-1) (see fig. 2 for location). During Meramecian 

time the Sadlerochit Mountains was an area of nondeposition; it was probably a land mass exposing both 

the Katakturuk Dolomite of Devonian or older age and 

sandstone and shales of the Neruokpuk Formation. A 

second transgression submerged the Sadlerochit high 

during Zone 16 ofthe Chesterian Series of Upper Mississippian. This transgression was probably gradual; it 

flooded the western Sadlerochit Mountains during the 

early part of Zone 16 and completely submerged the 

high during the later part of Zone 16. The Old Man 

Creek area probably was also submerged by the 

Meramecian transgression. 

Possible correlation lines (based on microfossil zones) 

between the four sections are illustrated in figure 2. 
ENVIRONMENTS OF DEPOSITION 11 

Diagrammatic 

cross section, 

Lisburne Group 

carbonate platform (free of 

significant terrigenous clastic 

influx I 

Facies 

Lithology 

Color 

Bedding and sedimentary structures 

Terrigenous clastics admixed or 

interbedded 

Algal mats 

Stromatolites 

Calcareous algae 

Sponge spicules 

Corals 

Brachiopods 

Bryozoans 

Echinoderms 

Ostracodes 

Basin-euxinic 

Shale, radiolarian chert, and 

siltstone 

Dark brown to black 

Very even millimetre laminations, rhythmic 

bedding, ripple 

cross laminations, burrows 

and worm trails 

on bedding surfaces 

Quartz silt and 

shale, finegrained siltstone; cherty 

Tidal shelf 

Interbedded thinto medium-bedded 

lime mudstone, 

dolomite, and 

chert 

Gray to brown 

Thoroughly burrowed. Thin to 

medium, wavy to 

nodular beds; 

bedding surfaces 

show diastems 

Quartz silt, 

siltstone, and 

shale; wellsegregated beds 

----· 

Toe-of-slope 

carbonates 

Interbedded limestone and darkgray shale 

Gray to dark gray 

Laminations may 

be minor, massive beds common. 

Lenses of graded 

sediments; lithoclasts and exotic blocks 

Small amount of 

shale, silt, and 

fine siltstone 

Foreslope 

Variable, depending on water 

energy upslope. 

Sedimentary breccia and lime 

sand or lime 

mudstone 

Gray to light gray 

Slumps in soft 

sediments, foreset bedding, exotic blocks 

Small amount of 

shale, silt, and 

fine thin-bedded 

siltstone 

Crinoid-bryozoan 

gardens 

Bedded crinoidbryozoan wackestone, packstone, 

and grainstone 

Light gray 

Massive to thick 

beds, some crossbedding 

Clastics rare 

---Salinity increases -

Sands on edge of 

platform 

Crinoid-bryozoan 

to ooid packstone and grainstone 

Light gray 

Medium-to largescale crossbedding; festoons 

common 

A small amount 

of admixed 

quartz sand 

Open platform 

Variable. Carbonate bryozoancrinoid packstone-wackestone; chert 

common 

Light gray 

Abundant burrows 

Clastics and carbonates in wellsegregated beds 

Restricted 

platform 

Finely and 

coarsely crystalline dolomite; 

dolomitic-crinoidbryozoan wackestone and packstone; dolomitic 

pelletoid lime 

mudstone 

Light gray to gr.ay 

Birdseye structure, algal mats 

on or near intertidal zone, stromatolites in 

very shallow 

water, graded 

bedding, crossbedded dolomite 

in tidal channels 

Clastics and carbonates in wellsegregated beds 

Intertidal to 

supratidal 

Irregularly laminated dolomite 

and dolomitic lime 

mudstone; anhydrite and calcite pseudomorphs of anhydrite common; 

algal mats; may 

grade into clastic red beds 

Gray, yellow, 

brownish red 

Anhydrite rhombs, 

bedded anhydrite, 

cracks, chips, 

algal mats 

Windblown landderived admixtures; clastics 

may be important 

components 

.... ~-· 

FIGURE 7 .-Generalized depositional environments of the Lisburne Group, north flank, eastern Brooks Range. 

During Zone 16 time in the three more westerly sections, open-platform sedimentation was dominant, although shoals of oolites and bioclasts were characteristic in the western Sadlerochit Mountains. Horizons of 

marked dedolomitization at 550 feet in the Plunge 

Creek section and 65 feet in the western Sadlerochit 

Mountains during Zone 16i suggest that uplift could 

have brought the rocks within a zone of fresh water at 

this time. It is possible that more landward conditions 

(restricted platform or intertidal) persisted in the Old 

Man Creek area. Later in the Chesterian (post-Zone 16) 

a marked regional regression occurred as suggested by 

the persistence of a restricted platform environment at 

the top of the Alapah Limestone. This shallowing went 

as far as intertidal conditions in the eastern Sadlerochit 

Mountains and Old Man Creek. 

The third regional transgression traceable in the Sadlerochit Mountains occurred at about the boundary of 

the Alapah and Wahoo Limestones. This transgression 

is indicated by the abrupt change from a restricted 

platform environment of the upper Alapah Limestone 

to an open platform-shoal environment of the lower 

Wahoo Limestone (Armstrong, 1973). Although figure 8 

shows that the plane of this transgression is not coincident with the boundary between the two formations, it 

must be remembered that this boundary was chosen in 

the field on the basis of a change of slope rather than on 

strictly lithologic characters. The plane of this Pennsylvanian (Morrowan) transgression probably approximates isochroneity better than the somewhat arbitrary 

boundary between these two limestone formations. The 

rocks deposited during the Morrowan (Zone 20) were 

open-platform grainstone and packstones throughout 

the area, but at about the Morrowan-Atokan boundary 

there was a probable regression, and shoal carbonate 

rocks (grainstones) became the dominant rock type. 

Oolitic grainstones are common in the eastern Sadlerochit Mountains, whereas ordinary bioclastic grainstones are dominant in the other sections. As in the 

other parts of the sections, the intergranular space of 

the grainstones has been completely obliterated by 

sparry calcite cement. 
12 DIAGENESIS AND STRATIGRAPHY OF THE LISBURNE GROUP LIMESTONES, NORTHEASTERN ALASKA 

Plunge Creek 

section 

70A-4/5 

§ c: § 0 Q) 0 

~ g~ c. "C. 

Wahoo Limestone 

Alapah Limestone 

Western Sadlerochit 

Mountains section 

69A-1 

Q) 

c. 

0 

~ w Oo ~~ 1ii 

"C. 

Eastern Sadlerochit 

Mountains section 

68A-4A/4B 

Old Man Creek 

section 

69A-4/4K 

J 

(_ 

~-------- ~-,---,---r7--;cr---,-----:r-~7-l 16s ---------

~~-- / / 

---- /// 

~~~~ ~ ,' 

//~ :";t---------;7-----?-------;?---:;~---:r-------71 \'i:,\ / 

//// 

1-------~ ,., / 

FEET METRES 

1()() f25 

0 0 

25 100 

VERTICAL SCALE 

14 

14 Numbers refer to microfossil zones 

FIGURE B.-Idealized graphs showing variation of depositional environments in the four stratigraphic sections. 

BIOSTRATIGRAPHIC CORRELATION 

Detailed discussions and faunal lists for the biostratigraphy of the Lisburne Group in the northeastern 

Brooks Range have been previously published, and 

these discussions and faunal lists are not repeated in 

this report. 

The regional correlation chart (fig. 2) for the Lisburne 

Group and the correlation diagram for the sections discussed in this report (fig. 9) are based on B. L. Mamet's 

microfossil zones. Lists of the microfossils for the eastern Sadlerochit Mountains section 68A-4A/4B were 

published by Armstrong, Mamet, and Dutro (1970) and 

for the Plunge Creek 70A-4/5 and western Sadlerochit 

Mountains 69A-1 sections by Mamet and Armstrong 

(1972). The Old Man Creek (69A-4/4K) section has been 

zoned by Mamet, and the microfossil lists are in manuscript. Microfossils have proved to be the most reliable 

and efficient means of correlation within the Lisburne 

Group and with the standard American and Eurasian 

type sections. 

The most conspicuous megafossils on the outcrop are 

rugose corals. Armstrong (1970a, 1972) analyzed the 

stratigraphic range of the lithostrotionoid corals and 

described parts of the fauna. He also (1973) described 

Wahoo Limestone corals of Atokan age, their paleoecology, and their regional distribution. In the Lisburne 

Group, corals are relatively abundant in Meramecian 

and Atokan age beds but scarce in Osagean and Chesterian beds. Their stratigraphic range is generally 

longer than individual microfossil zones; individual 

species of corals generally range through three or more 

microfossil zones. 

Mamet and Armstrong (1972) reported that at the 

Plunge Creek section the Kekiktuk Conglomerate, 

which directly overlies the Neruokpuk Formation, is 

about 25 feet thick and is overlain by 1,295 feet of shales 

and argillaceous limestones of the Kayak (?) Shale. 

Mamet and Armstrong (1972) described a microfauna 

and corals of Zone 11, Meramecian, in the Kayak(?) 

Shale about 550 feet above the N eruokpuk. As shown in 

figure 2, the Kayak(?) Shale is thin in the Sadlerochit 

Mountains, only about 50 feet thick in the western 

Sadlerochit Mountains section, and absent from the 

eastern Sadlerochit Mountains section. There the 

Alapah Limestone of Chesterian age rests directly on 

the N eruokpuk Formation. In the Old Man Creek section to the southeast, the Kayak(?) Shale contains 

lithostrotionoid corals and microfossils of Zone 14, 

Meramecian, and is at least 300 feet thick. Here exact 
BIOSTRATIGRAPHIC CORRELATION 

z 

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Sea cliffs of northwestern Alaska 

Armstrong, Mamet, and Dutro (1971) 

Western 

Brooks 

Range 

Central Brooks 

Range 

Armstrong, Mamet, and Dutro (1970) 

Shainin Lake 

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FIGURE 9.-Regional correlation chart for the Lisburne Group of arctic Alaska. 

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13 

thickness of the Kayak(?) Shale is difficult to determine 

because of complex faulting at the base of the section. 

In the Sadlerochit Mountains and adjacent areas, the 

Mississippian rock unconformably overlies rocks of Devonian or older age. At the western Sadlerochit Mountains section, the 50 feet of Kayak(?) Shale at the base of 

the Carboniferous section unconformably overlies the 

Devonian or older Katakturuk Dolomite (Dutro, 1970). 

In the other three sections, Carboniferous strata overlie 

the Neruokpuk Formation, which is Precambrian, 

Cambrian, and pre-Mississippian (Dutro and others, 

1972). 

Mamet identified a transition Zone 12/13 Meramecian microfauna at the base of the Alapah Limestone, 

Plunge Creek section (70A-4/5) (Mamet and Armstrong, 1972). The base of the Alapah Limestone in the 

western Sadlerochit Mountains 69A-1 section is lower 

Chesterian, Zone 16i, and in the eastern Sadlerochit 

Mountains section it is Zone 16s, lower Chesterian. 

Southeast of the Sadlerochit Mountains at the Old Man 

Creek section (69A-4'4K), the base of the Alapah 

Limestone is Zone 16i. The Wahoo Limestone, here of 

Pennsylvanian age, contains the youngest beds of the 

Lisburne Group in the report area. In the Plunge Creek, 
14 DIAGENESIS AND STRATIGRAPHY OF THE LISBURNE GROUP LIMESTONES, NORTHEASTERN ALASKA 

western Sadlerochit and eastern Sadlerochit Mountains 

sections, the top of the Wahoo Limestone is Atokan in 

age, whereas in the Old Man Creek section it is 

Morrowan. 

In the area of this study, the lower (Permian) part of 

140" 

the Sadlerochit Formation unconformably overlies the 70" 

Wahoo Limestone. Detterman (1970) reported that the 

basal Echooka Member of the Sadlerochit Formation 

contains a brachiopod fauna oflower Kazanian, earliest 

Late Permian age. The unconformity represents a 

hiatus including DesMoinesian, Missourian, and Virgilian (Pennsylvanian), and Wolfcampian, Leonardian, 

and possibly lower Guadalupian (Permian) time. The 

westward thinning of the Atokan carbonate rocks, in 

the Sadlerochit Mountains (fig. 2) and to the southeast 

at Old Man Creek, suggests differential erosion, probably owing to differential uplift previous to Sadlerochit 

Formation sedimentation. At many localities the highest few feet of Atokan carbonate rocks show evidence of 

vadose weathering in the form of enlarged vertical 

joints and vugs that are filled with a clay similar to terra 

rossa. The basal beds of the Echooka Member are conglomerate or conglomeratic sandstone formed partly by 

rounded chert and limestone pebbles and cobbles derived from the underlying Wahoo Limestone. 

REGIONAL RELATIONS OF CARBONIFEROUS 

CARBONATE ROCKS IN THE 

SADLEROCHIT MOUNTAINS 

Carbonate rocks of the Lisburne Group in the Sadlerochit Mountains and adjacent areas are part of the 

Carboniferous regional marine transgression of arctic 

Alaska. Carboniferous rock outcrop patterns in the 

Brooks Range are shown in figure 1 and in a regional 

correlation chart (fig. 9). Also shown are the significant 

exploration wells that have penetrated to the Devonian 

or older rocks. Brosge, Dutro, Mangus, and Reiser 

(1962) defined the northward transgressive nature of 

the Lisburne Group carbonate rocks in the central and 

eastern Brooks Range. These studies were continued by 

Armstrong, Mamet, and Dutro (1970), Mamet and 

Armstrong (1972), and Armstrong (1974), who also delineated the Sadlerochit high that appears in part to 

parallel the present-day Sadlerochit and Shublik 

Mountains. 

Armstrong and Mamet (1970) recognized in the 

Philip Smith Mountains and, from subsurface data, the 

existence of a thicker accumulation of carbonate rocks 

in a northeastern-southwestern trend. This negative 

area of thicker carbonate rocks was named the Canning 

sag. 1 

The northward marine Carboniferous transgression I 

is shown in carbonate lithofacies maps (fig. 10 and 11) I 

and diagrammatic reconstructed cross sections (fig. 12). 1 

sao EXPLANATION 

EB Meas~~~~ioo~tcrop 

4 Well section 

50 0 50 100 150MILES 

50 0 50 100 150 KILOMETRES 

FIGURE 10.-Lithofacies map of northeastern Alaska at the end of 

Meramecian time. 

The residual positive area, the Sadlerochit high, was 

formed by Devonian carbonate rocks and the metamorphosed clastic rocks of the Neruokpuk Formation. The Sadlerochit high was probably a major source 

area for clastic material in the Kayak(?) Shale of the 

region. It remained above sea level through Meramecian time and was finally submerged in early Chesterian time (Zone 16s). The Chesterian carbonate sediC T I C 

50 0 50 100 150 MILES 

50 50 100 150 KILOMETRES 

FIGURE H.-Lithofacies map of northeastern Alaska near the end of 

Chesterian time. 
REGIONAL RELATIONS OF CARBONIFEROUS CARBONATE ROCKS IN THE SADLEROCHIT MOUNTAINS 15 

North 

~ I 

Wahoo Limestone 

lOMILES 

10 KILOMETRES 

South 

21 ~ 

20 ~ 

Kekiktuk 

Conglomerate 

~ 

FIGURE 12.-[dealized cross section of the Carboniferous sediments before deposition of the Sadlerochit Formation. The cross section extends southward from section 69A-1, western Sadlerochit Mountains, to the junction of the Canning River and Marsh 

Fork, sections, 70A-'213. See figure 2 for location. 

ments that overlapped the old Sadlerochit high were 

deposited in shallow water. Armstrong (1973) reported 

that intertidal sedimentary structures such as algal 

mats, birdseye structures, and small lithoclasts are 

common in the upper part of the Alapah Limestone in 

the Sadlerochit Mountains (fig. 2). 

The diagrammatic cross section (fig. 12) illustrates 

the northward transgression in the Philip SmithFranklin Mountains and the onlap over the Sadlerochit 

high. 

The lithofacies maps shown in figures 10 and 11 incorporate subsurface data from exploration wells on the 

North Slope. Atlantic Richfield/Humble Prudhoe Bay 

State Well No.1, near the axis of the Canning sag, has 

more than 1,250 feet of shallow-water, open-platform 

carbonate rocks that range from Chesterian (Zone 16) to 

Atokan (Zone 21) age. The carbonate rocks are underlain by about 550 feet of black and red shale, siltstone, 

sandstone, and thin coal seams that are probably the 

Kayak(?) Shale. West of this well (fig. 1) the carbonate 

sections thin. The Union Oil Kookpuk No. 1 well has 

about 900 feet of Chesterian to Atokan age carbonate 

rocks, whereas to the north the Sinclair/British Petroleum Colville No. 1 has only 300-400 feet of Morrowan and Atokan age carbonate rocks. Chesterian age 

sediments may be represented by about 400 feet of 

dark-gray to red siltstones, shales, and sandstones, 

which overlie the pre-Carboniferous argillites. Further 

west and south ofPoint Barrow (fig. 1) the United States 

Navy's wells-Barrow No. 3, Topagoruk, and East 

Topagoruk-are devoid of Carboniferous carbonate 

rocks, and above the pre-Carboniferous argillites is a 

thin sequence of clastic shales and sandstone. These are 

unfossiliferous but may be of Carboniferous age. No 

deep tests have penetrated the Carboniferous section 

south of the Topagoruk well or west of the Colville 

River. Thus, except for scant aeromagnetic and seismic 

data, little is known of the subsurface carbonate strata 

in Naval Petroleum Reserve No. 4 or the area to the 

west. Projection of Carboniferous outcrops from the De 

Long Mountains and Lisburne Hills into the subsurface 

(not shown in figs. 10 and 11) is complicated because in 

both areas the Carboniferous rock exposures are part of 

large-scale gravity-slide thrust sheets with dislocations 

of 60-70 miles in the De Long Mountains (Martin, 

1970). 

GRAPHIC REGISTRY OF STRATIGRAPHIC 

SECTIONS 

The locations of the stratigraphic sections described 

in this report are shown in figures 13-16. Maps by 

Reiser, Dutro, Brosge, Armstrong, and Detterman 

(1970) and by Reiser, Brosge, Dutro, and Detterman 

(1971) give detailed geologic settings for the sections. 

DIAGENESIS 

For the purpose of this paper, diagenesis includes all 

changes that sediments undergo from time of deposition 

until the present. One of these changes is 

lithification-that is, the change from unconsolidated 

sediment to consolidated sediment by compaction, 

cementation, and pressure solution. As discussed by 

Purdy (1968) in his admirable summary of environmental factors, diagenesis has necessarily vague limits, and 

in this study even the localized products of metamorphism along a thrust plane have been included within 

its realm. 

The importance of comparing unconsolidated sediments with their recent lithified counterparts is that 

processes active at the present time can be extrapolated 

into the geological past. Although this is the standard 

procedure of geologic deduction, it must be remembered 

that variation in sea level in the Holocene, an important 
16 DIAGENESIS AND STRATIGRAPHY OF THE LISBURNE GROUP LIMESTONES, NORTHEASTERN ALASKA 

T 

2 

s 

R.24 E. 

11 12 

14 13 

23 24 

26 25 

I 

35 

~c Township and range grid from 

U.S. Geological Survey 1 :63,36'), 

Mt. Michelson A4, A5, 1955 

R.25E. 

18 17 

20 

30 29 

31 32 

FIGURE 13.-Location map of Plunge Creek sections 70A-4 and 

70A-5, Mount Michelson A-4 and A-5 quadrangles. 

parameter in controlling changes in limestone fabrics, 

is related to the melting of the Pleistocene glaciers. So, 

at least as far as carbonate diagenesis is concerned, the 

present is not ~~the key to the past" but rather that ~~the 

present is the key to the Triassic2 "! 

CALCITE 

The study of calcite fabrics has proved a fruitful 

method of deciphering the geologic history of limestones. No longer are limestones just limestones to most 

geologists. Nearly all now appreciate the advantages of 

subdividing the various limestone rock types on an objective basis as has so universally been accepted for the 

igneous rocks. In contrast to the subdivision of other 

major rock groups, nonrecent limestones are now nearly 

monomineralic, being composed of low-Mg calcite. Recent limestones are composed of two distinct 

2With affectionate acknowledgment to the late Dr. P. D. Krynine for this analogy between 

the Permo-Carboniferous and Pleistocene glaciations. 

T. 

3 

N. 

R.25E. 

11 

14 

23 

26 

35 

Township and range grid from 

U.S. Geological Survey 1:63,360, 

Mt. Michelson C-4,1955 

12 

13 

0\ 

69A~ 

24 

1

So0 '-J. 

25 

36 

R.26 E. 

7 8 

18 17 

19 20 

30 29 

31 32 

FIGURE 14.-Location map of western Sadlerochit Mountains 

section 69A-1, Mount Michelson G-4 quadrangle. 

polymorphs ofCaC03 namely calcite and aragonite; the 

calcite occurs in both low-Mg and high-Mg forms, which 

contain 0-5 percent and 11-19 percent Mg in solid solution, respectively (Chave, 1954). Both aragonite and 

high-Mg calcite, the dominant modern carbonate minerals, are metastable under normal conditions, and it is 

the processes of conversion to stable low-Mg calcite, 

together with organic influences, that are largely responsible for diversity of fabric types in ancient limestones. 

The description of limestones best follows the major 

subdivision into grains, matrix (carbonate mud), and 

cement (sparry calcite) used for sandstones by Krynine 

(1948). This primary subdivision then allows the use of 

either of the currently most popular and largely objective limestone classification, that is, Dunham (1962) or 

Folk (1959). The Dunham classification is used 

throughout this report (as outlined in table 1) because of 

the genetic significance of mud-supported as opposed to 

grain-s up ported limestones. 
CALCITE 17 

T. 

4 

N. 

T. 

3 

N. 

R.30 E. 

35 36 

2 1 

11 12 

14 13 

23 24 

Township and range grid from 

U.S. Geologioal Survey 1 :63,360, 

Mt. Michelson C-1,1955 

R.31 E. 

31 32 

6 5 

o).68A-4B 

820'~ ' 

6BA-4i820, 

7 1692 8 

18 17 

19 20 

FIGURE 15.-Location map of eastern Sadlerochit Mountains sections, 

68A-4A and 68A-4B, Mount Michelson G-1 quadrangle. 

GRAINS 

The grains in the Lisburne Group are largely of bioclastic origin (that is, crinoids and bryozoa) together 

with the so-called ~~inorganic" grains such as pellets and 

oolites. 

CRINOIDS 

Crinoids are the dominant bioclastic element in the 

Lisburne Group, and although common throughout the 

section, they are preferentially developed in the grainstone intervals. The crinoid debris was originally composed ofhigh-Mg calcite, although Schroeder, Dwornik, 

and Papike (1969) have shown variations between 3 and 

43 mole percent of Mg2+ in the skeleton. Individual 

grains are recognized by the rectangular pattern of 

pores of the spines or by concentric arrangement of 

dusty inclusions in the columnals surrounded by clear 

sparry calcite. Although these individual grains optically act as a single crystal, Nissen (1963) suggested 

that in reality the grains consist of an agglomeration of 

individual crystals whose c-axes are perfectly alined. 

T. 

1 

N. 

9 10 

16 15 

21 22 

28 27 

33 34 

Township and range grid from 

U.S. Geological Survey 1:63,360, 

Mt. Michelson B-1 ,1955 

R. 32 E. 

11 12 

~ 

14 13 

Bo- Ba- 691 ,1 ~9A-4K 1

<o0 . 24 

26 25 

35 36 

FIGURE 16.-Location map of Old Man Creek sections, 69A-4 and 

69A-4K, Mount Michelson B-1 quadrangle. 

These ngrains" have a spongelike structure with collagen fibers in the hollow spaces (Nissen, 1969). The fact 

that the skeletal elements of recent crinoids in high-Mg 

calcite, as well as ancient crinoid debris now preserved 

in low-Mg calcite, optically act as single crystals implies 

that the mineralogical conversion takes place on a 

molecule for molecule basis without large-scale solution. Bathurst (1971, p. 357) pointed out that low-Mg 

calcite is deposited in the pore spaces of the echinoderms 

at the same time as first-phase sparry calcite cement. 

This cementation occurs prior to the loss of Mg 2+ from 

the original high-Mg calcite. H. D. Winland (oral commun., 1970) considered it quite probable that the lowMg calcite syntaxial overgrowth is formed while the 

echinoderm nucleus is still high-Mg calcite. If, as seems 

probable, early cementation obliterates the intragranular spaces, it follows that nucleation of intragranular 

chert (see section on ~~Intragranular Chert") must have 

taken place prior to the first phase of cementation. 
18 DIAGENESIS AND STRATIGRAPHY OF THE LISBURNE GROUP LIMESTONES, NORTHEASTERN ALASKA 

Evamy and Shearman (1965) described the stages of 

syntaxial development of sparry calcite by tracing the 

variation of ferrous iron content. They showed that 

overgrowths developed preferentially in the direction of 

the c-axes of echinoderm fragments. In the Lisburne 

Group, however, no iron was found in the overgrowths. 

The syntaxial cement usually lacks foreign matter (pl. 

9, fig. 2); the cement probably formed progressively in 

space made by pushing aside any intergranular mud. 

BRYOZOA 

Together with crinoid debris, bryozoan detritus is the 

most common bioclastic element in the Lisburne Group. 

In contrast to the observations of Davies (1970, p. 134) 

in Shark Bay, Western Australia, where bryozoans, 

although a common member of the biota, are rare as 

fragments in the sand-size sediments, sand-size detritus of bryozoan fronds are abundant in the Lisburne 

Group. Although recent bryozoans have either high-Mg 

calcite or aragonite in their skeletons (Chave, 1954; 

Sandberg, 1971), in contrast to organisms like 

pelecypods, the skeletons appear to retain a large proportion of fabric detail through geologic time (pl. 2, figs. 

1-5). The zooecia, the living spaces of the organisms, in 

the Lisburne Group are filled with either carbonate 

mud or sparry calcite that is independent of the nature 

of the intergranular material. Reworking is probably 

indicated where the zooecia are filled with calcite that is 

different from the intergranular material. In some Lisburne Group samples (pl. 2, fig. 4), the nature of the 

intrazooecial calcite probably reflects the habit of the 

original organic material. 

OTHER BIOCLASTIC DEBRIS 

Ara~onit~ b_i~clastic grain 

wtth mtcrtttc envelope 

' 

,. First-stage CaC03 cement 

Dissolution of aragonite clast 

First-stage CaC03 provides 

strength to mold 

Complete cementation by secondphase CaC03 cement 

FIGURE 17 .-Probable sequence of alteration of aragonite bioclast debris. 

which is cemented by sparry calcite." Collapsed micrite 

envelopes have been recorded (Bathurst, 1964), but 

quantitatively they are rare and have not been observed 

in the Lisburne Group. 

Land (1967), as discussed in a later section, showed 

that the deposition of early-phase sparry cement occurs, 

mostly as a fringe around the clastic grains, prior to the 

solution of the aragonite. It is then possible (see pl. 1, fig. 

6) that the early cement fringe, together with the micrite envelope, makes the void that results after solution 

Other bioclastic debris is rare in the Lisburne Group of the aragonite sufficiently rigid to be preserved until it 

and consists mainly of pelecypod fragments (pl.1, fig. 6) is subsequently infilled by the precipitation of sparry 

and rare solitary corals. These fragments almost invar- calcite. Winland (1968) has shown that micrite eniably do not exhibit the details of the original vel opes are sometimes originally composed of high-Mg 

shell-only the original outline is preserved in a dark calcite, whereas Bathurst (1964) stated that an original 

thin outer zone that encloses an infilling of sparry cal- aragonitic composition is more common. Only rarely is 

cite cement. This change of texture is related to the the internal structure of originally aragonitic bioclasts 

solution of the original aragonitic shell and to the sub- preserved in low-Mg calcite. In these bioclasts the 

sequent reprecipitation ofCaCOa as low-Mg calcite. The change ofCaCOa polymorph has almost certainly taken 

dark outer rim is generally considered (Bathurst, 1971, place in solution and by immediate redeposition 

p. 333) to be a result of the infilling of algal borings by molecule by molecule. 

carbonate mud Ctmicrite envelope"). The preservation The original internal structure of fibrous pelecypods 

of the cast of the original shell after solution and prior to is, however, sometimes preserved in intragranular 

complete infilling by sparry calcite, reveals the possible chert (see pl. 9, fig. 5), providing further evidence of the 

sequence of alteration of aragonite bioclast debris (fig. early nucleation of this type of chert. The original 

17). As recorded by Logan, Read, and Davies (1970, p. 62) chamberlets of the probable pelecypod are still outlined 

in the Pleistocene Carbla Oolite of Shark Bay, Western by dark inclusions; the presence ofthese inclusions sugAustralia, ttaragonitic fossils have been dissolved gest that they are a remnant after solution of the origipreferentially leaving moldic porosity, whereas calcitic nal shell. 

skeletal material remains intact. The molds and intact Foraminifera (for convenience included as ttbioclasfossils are set in a matrix of calcitic skeletal debris tic") occur more commonly toward the base of the 
CALCITE 19 

stratigraphic section, especially where the rocks are 

shaly. They also occur more rarely in the oolite grainstones of the Wahoo Limestone, and their margins appear to grade into intergranular sparry calcite cement. 

OOLITES 

Oolite grainstones are the dominant rock type in the 

Wahoo Limestone of all four sections considered in this 

study. The individual oolites show great variation in 

shape, and only very rarely do they approach the spherical shape of the ideal oolite. The oolites have a welldeveloped core, usually a bioclast, while the oolitic skin 

ranges in thickness from one to four distinct layers. The 

fabric of the individual oolite skins is both radial and 

tangential to the core, and only rare patches of the skin 

are cryptocrystalline calcite. The shape of an oolite is a 

function of the shape of the bioclastic core: elongate 

around a pelecypod fragment but equidimensional 

around a crinoid plate. The thickness of oolitic skins is 

apparently independent of the shape of the core; in some 

samples (pl. 1, fig. 2) the thickest oolitic skin occurs 

around elongate bioclasts, while in others equidimensional grains possess the thickest oolitic coating (pl. 1, 

fig. 3). The agglutinated foraminifer on plate 1, figure 3, 

is the only grain in the field of view with no oolitic 

skin-probably because oolitic growth is difficult on a 

mineralogically heterogeneous base. In the same field, 

the core of an oolite is occupied by a single coarse rhomb 

of dolomite that probably developed after the oolitic 

coating. Some of the pelecypod bioclasts are now represented by void-filling calcite showing no original fabric. These bioclasts indicate solution of an originally 

aragonitic shell, leaving a void that was subsequently 

infilled with sparry calcite cement after the formation of 

the oolite; the oolite itself was changed to calcite on a 

piecemeal basis. Compound nuclei, probably originally 

in the form of detrital carbonate rock fragments, also 

occur (pl. 1, fig. 2). The encrusting algae Osagia is commonly associated with the oolitic facies (pl.10, figs. 3-5), 

emphasizing the influence of encrusting organisms in 

highly agitated environments. Tillman (1971) suggested that Osagia is not necessarily associated with 

shallow water. 

Origin of the oolite fabric.-Modern oolites, as those 

currently being deposited on the Bahama Banks 

(Newell and others, 1960) and the Trucial Coast of 

Arabia (Kendall and Skipwith, 1969), are composed of 

aragonite. Ancient oolites have changed to calcite, the 

more stable form ofCaCOa. This is true of the oolites in 

the Lisburne Group, but despite this change, the original tangential arrangement of individual crystals has 

survived. Shearman, Twyman, and Zand Karimi (1970) 

have clearly shown that retention of the original 

tangential fabric in oolites is related to tangential 

crystals of aragonite in a diffuse matrix of organic 

mucilage separated by distinct concentric layers of 

mucilage. The transformation of aragonite to low-Mg 

calcite apparently takes place in solution molecularly, 

and this process allows the fine detail of the concentric 

layers of mucilage to be preserved. The calcite tends to 

develop perpendicular to the surfaces of the concentric 

mucilage layers to form radial partitions with their 

c-axes parallel to their length, pushing aside the diffuse 

mucilage (see fig. 18). It therefore is obvious that the 

radial fabric so common in oolites is a diagenetic rather 

than a primary feature. The rare patches of cryptocrystalline calcite are probably produced by local largescale solution of aragonite; this process would leave the 

mucilage layers unsupported and permit their collapse, 

or as suggested by Twyman (1970), the calcite may infill 

the cavities created by algal boring. 

Cementation of oolites.-As mentioned in the previous section on depositional environments, oolites are 

formed by high-water energy on shoals or deltaic fiats 

from which available carbonate mud has been winnowed. This process implies that most oolitic rocks are 

of the grainstone type with most of the intergranular 

space available for subsequent sparry calcite cementation. The rarer specimens of oolites that are associated 

with carbonate mud have probably been moved from the 

site of their formation. Their cementation history differs little from other clastic grains, but examples of 

oolitic skins detached from their core (pl. 1, fig. 4) provide good evidence that compaction occurred before the 

Tangential 

aragonite 

Concentric layers 

of mucilage 

Solution --- Precipitation of 

radial calcite 

Calcite crystals 

push diffuse 

mucilage aside 

to form radial 

partitions 

FIGURE 18.-Diagram showing the alteration from tangentially 

arranged aragonite crystals to radially arranged calcite crystals 

within the concentric mucilaginous layers of an oolite (from 

Shearman and others, 1970, fig. 4). 
20 DIAGENESIS AND STRATIGRAPHY OF THE LISBURNE GROUP LIMESTONES, NORTHEASTERN ALASKA 

major second phase of cementation. The original core is 

outlined by first-phase sparry calcite crystals with 

c-axes at right angles to the inner surface of the oolite 

skin. Displacement of the oolite skin from the core took 

place along two planes of movement, probably the result 

of compaction. The newly formed void adjacent to the 

original core and the remainder of the core itself were 

later filled with equant second-phase sparry calcite cement. As with similar examples described by Shearman, Khouri, and Taha (1961) from the Jurassic limestones ofthe French Jura, early-phase cement is poor in 

iron and is related to the aragonite-low-Mg calcite 

transition, but the second-phase cement is rich in iron. 

Mechanism of oolite formation.-The mechanism of 

oolite formation is still a matter of dispute, but the 

presence of an organic matrix in oolites similar to that, 

for example, in pelecypod shells suggests that it is not a 

purely inorganic process. 

The classical hypothesis for the development of oolites is the snowball mechanism, described by Sorby as 

early as 1879, which involves the accretion of aragonite 

needles on a nucleus in shallow sea water supersaturated with CaCOa, which, as a result of constant 

rolling, would allow the development of concentric 

layers. This theory discounts any influence of the organic matrix in oolitic development, and in addition, 

Donahue (1965) has pointed out that the highly 

polished outer surface of growing oolites is difficult to 

reconcile with a hypothesis of mechanical accretion. 

Twyman (1970) stated that ((the high degree of surface 

lustre of oolites is not necessarily due to abrasion. It 

seems rather more likely that the thin skin of organic 

matter which characteristically coats nearly all oolite 

grains in the Al Bahrani delta of Abu Dhabi acts like a 

coat of varnish to make the oolite grains shiny." 

The similarity between the nature of the organic content of calcium carbonate skeletons of invertebrates and 

oolites is the clue to the biochemical origin of the original oolitic aragonite. Simkiss (1964) and Kitano and 

Hood (1965) have shown that the nature of the organic 

matrix is the main influence on the calcium carbonate 

polymorph formed during construction of the shell. This 

matrix is composed of a peptide-polysaccharide complex 

that ccprovides nucleating sites for CaCOa either by acting as a template for epitaxial nucleation or by its ability to attract the appropriate inorganic ions electrostatically" (Mitterer, 1971, after Wilbur and Simkiss, 

1968). Although epitaxis is probably the dominant 

mechanism of test or skeleton construction in CaCOa, 

Blow and Brooks (1975) consider that a nonepitaxial 

mechanism, whereby the formation of largely organic 

colloid systems may act to concentrate CaCOa on 

micelle structures (Duck, 1966), may be more appropriate for some Foraminifera. Mitterer (1971) illustrated 

a series of amino acid chromatograms of the chlorophyte 

alga Halimeda, three mollusks, and two specimens of 

modern oolites (all of which are originally aragonitic). 

Not only is the amount of protein in the oolites of the 

same order of magnitude as that of the mollusks (2--4 

micromoles per gram of CaCOa), but there is also a 

remarkable similarity in the overall chromatograph 

pattern. Aspartic acid, glycine, alanine, leucine, and 

lycine are the dominant aniino acids in the algae, mollusks, and oolites. Unfortunately, Mitterer (1971) does 

not refer to the sampling location of the algae and mollusks, and therefore the possibility that the distribution 

of amino acids is related to the environment rather than 

to the species independent of environment cannot be 

completely discounted. The above argument, especially 

in view of the evidence that calcium carbonate does not 

precipitate inorganically on coated grains (Chave and 

Suess, 1967) suggests that the origin of oolites has a 

large biochemical element. Mitterer (1971), however, 

has pointed out that if the argument is taken further, 

oolites would be expected wherever organically coated 

grains occur in water supersaturated with CaCOa. This 

does not agree with the facts. Further work on the 

distribution of organic matter in carbonate shoal areas 

is necessary before this question can be completely resolved. 

PELLETS 

The pellets in the Lisburne Group are well distributed throughout the Alapah Limestone but are rare in 

the Wahoo Limestone. In general, pellets are concentrated in wackestone and packstone rock types and 

occur only sporadically in grainstones. The pellets are 

homogeneous in internal fabric, and their well-rounded 

outlines tend to be preserved. There is no evidence to 

suggest that the pellets are anything but fecal remains. 

But no trace remains of the organisms that produced the 

pellets. 

CEMENT 

Cement is defined as an intergranular material introduced into the rock as a precipitate from interstratal 

solution, and it is not the product of clastic sedimentation. To provide for the introduction of cement, it is 

necessary to have a framework that will preserve void 

spaces prior to cementation. The most common 

framework in carbonate rocks is a grain-contact fabric, 

that is, grainstone of Dunham (1962), where intergranular carbonate mud is almost absent. Another 

framework that permits the introduction of cement is 

an already lithified carbonate rock from which the more 

soluble mineral has been taken into solution, for example, voids after aragonite shells in a calcite host or voids 

after calcite clasts in a dolomite host. 
CALCITE 21 

SPARRY CALCITE CEMENT 

Primary pore space, that is, intergranular space, is 

absent from the Lisburne Group. In grain-contact rocks, 

where there is little or no carbonate mud; the potential 

pore space has, without exception, been obliterated by 

sparry calcite cement. In mud-supported rocks, sparry 

calcite cement exists only as a void filling after sol uti on 

of originally aragonitic shells. Winnowing in a highenergy environment allows the available carbonate 

mud to be removed to a lower energy environment. 

The distribution of sparry calcite cement in the grainstones of the Lisburne Group is discussed in the section 

((Environments of Deposition." The depositional environment of the cemented grainstones is considered to 

have been a shallow-water shoal. Grainstones, except 

for a 400-foot interval toward the base of the western 

Sadlerochit Mountains section (69A-1), are rare in the 

Alapah Limestone. In the Wahoo Limestone, however, 

completely cemented grainstones (often oolitic) are the 

dominant rock type. Two distinct phases of sparry calcite cement are apparent in the Lisburne Group. The 

first-phase cement forms a thin fringe of relatively constant thickness ( ~30~-t-m) around the clastic carbonate 

grains (see pl. 1, figs. 1-6) with stubby crystals with 

pyramidal terminations growing at right angles to the 

grain margins or as syntaxial overgrowths on 

echinoderms. In recent limestones these early fringes 

are part of Stage II of Land's six stages of cementation 

(Land and others, 1967), usually formed by meteoric 

water above the water table (that is, vadose zone). The 

nature of the fringe cement in recent grainstones appears to be a function of access to salt water. In the 

intertidal zone the beach rock cement is either aragonite or high-Mg calcite, whereas away from the marine 

influence, the meteoric environment produces a low-Mg 

calcite fringe cement (Bathurst, 1971, p. 368). 

Although the fabrics recorded from recent limestones 

are comparable with those of the Lisburne Group [cf. the 

isopachous beach rock cement of the Pleistocene Belmont Formation of Jamaica (Land, 1971, p. 135)], it is 

not possible to assess the original mineralogy of the 

early-phase cement in the Lisburne Group. A fossil example comparable to that found in the Lisburne Group 

is the ((short, closely packed, calcite druse" described by 

Purser (1969) from the Middle Jurassic of the Paris 

Basin. and it is suggested as being originally calcitic. 

Except for the two zones of dedolomitization (see section on ((Environments of Deposition"), or the intertidal 

algal mat of the eastern Sadlerochit Mountains section 

(68A-4A/4B), there is no evidence ofbreaks of sedimentation in the Lisburne Group. Thus, in general, although the Lisburne early cement has textural 

analogies with recent examples from a vadose zone, it 

probably formed in a subtidal environment. This cement probably originated as a precipitate of calcium 

carbonate from supersaturated tropical sea water, as 

described by Taylor and Illing (1969) and Shinn (1969) 

in the Arabian Gulf. 

Second-phase sparry calcite completely obliterates 

the available pore space with subequant crystals that 

are much coarser than the first-phase cement. Crystal 

size tends to increase toward the center of a void fill. 

There appears to have been a time lapse between the 

two phases of cement, the second phase of which tends to 

be rich in Fe2+ (as discussed in the section ((Fe:2+ in 

Calcite"). The evidence from oolitic skins displaced from 

the now dissolved core (pl. 1, fig. 4) and the existence of 

enfacial junctions (Oldershaw and Scoffin, 1967; 

Bathurst, 1971, p. 434) support this view. The secondphase cement presumably formed after the conversion 

of all metastable carbonate minerals to low-Mg calcite 

(part of Land's stage IV of cementation (1967)). 

Internal silts similar to those described by Dunham 

(1969) from the Permian limestones of New Mexico and 

ascribed to the vadose zone are absent from the Lisburne Group. This fact, together with the apparent continuity of sedimentation, suggests that the secondphase cement developed in a phreatic environment. 

The source of the CaC<h necessary for complete 

cementation implies that the second-phase cement, at 

least, is from a distant source (analogous to the distantsource dolomite of Murray, 1964). Bathurst (1971, p. 

457) suggested that neither solution of local aragonite, 

especially in view of the lack of collapsed micrite envelopes, nor pressure solution will provide sufficient 

volume to obliterate the intergranular space. But if 

submarine precipitation of CaCOa is invoked, then the 

regional distribution of sparry calcite is left unexplained. 

Illing, Wood, and Fuller (1967) suggested that the 

relative amount of available second-stage sparry calcite 

cement is partly a function of the tectonic setting of the 

area. For example, primary intergranular porosity is 

very common in the limestones of the Arabian Gulf 

where continuous calcareous sedimentation has persisted throughout most of the Mesozoic and Tertiary 

eras, whereas in North America, where interrupted 

cratonic limestone deposition is dominant, very little 

primary pore space has escaped cementation by sparry 

calcite. 

At the conclusion of this discussion, however, we still 

have no answer as to the origin of the second-phase 

cement. We can only suggest that a very large proportion of originally aragonitic bioclasts, without micrite 

envelopes, has gone into solution and has disappeared 

from the geological record. This process could provide a 

very large amount of cement and would also explain its 

regional variation in distribution. 
22 DIAGENESIS AND STRATIGRAPHY OF THE LISBURNE GROUP LIMESTONES, NORTHEASTERN ALASKA 

NEOMORPHIC PROCESSES 

Neomorphism (Folk, 1965) is an increase or decrease 

in crystal size. For calcium carbonate, this generally 

involves a change of lattice type (for example, the 

change from aragonite to low~Mg calcite) and it has 

been dealt with in the preceding discussion. It also includes a change in crystal size without change of lattice 

type, a process usually referred to as recrystallization. 

The product of the latter process is either aggrading or 

degrading in form and, in our experience, is quantitatively of minor importance. 

The operational criteria for recognizing neomorphic 

spar have been outlined by Bathurst (1971, p. 484); he 

also emphasized that recrystallization is a wet rather 

than a dry process. Aggrading neomorphic fabrics have 

not been positively recognized in the limestones of the 

Lisburne Group, but this process is invoked to explain 

the grain size of probable syngenetic macrodolomites. 

The average grain size of recent syngenetic dolomites is 

about 4J.tm (L. V. Illing, oral commun., 1970), whereas 

macrodolomite grains of the Lisburne often exceed 50 

micrometres, and even the microdolomite grains commonly are larger than 10 micrometres. These sizes suggest that an aggrading process operates in dolomite 

through geologic time, the maxim urn grain size 

achieved being a function of the available pore fluids. 

The only positive evidence of degrading neomorphism 

is illustrated on plate 6, figure 1; the illustration shows 

that the crystal size in a crinoid plate and its syntaxial 

overgrowth has decreased while the matrix (probably 

originally carbonate mud) and bryozoan fragments 

have increased in grain size. In the end stage of 

neomorphism, this rock would be a dusty equigranular 

calcite mosaic from which all evidence of bioclastic remains has been eliminated. The formation of marble 

(see the section on ~~Marble") after thrust movement is a 

process closely analogous to sedimentary neomorphism 

except that large-scale stress is the trigger mechanism 

for annealing the crystals. 

MATRIX 

Matrix is defined as intergranular material. It is usually composed of carbonate mud (micrite) and is domin~ 

antly of clastic origin. The separation of grains and 

matrix is to some extent a function of the scale of observation, but in practice a tendency toward a bimodal size 

distribution in micritic limestones makes the disti-nction easy. Individual crystals of micrite have an upper 

size limit of 3-4 micrometres (Bathurst, 1959). 

Carbonate mud is the dominant intergranular material in the Alapah Limestone, although toward the base 

of the Plunge Creek section (70A-4/5) the matrix contains a relatively high proportion of clay minerals. 

Recent carbonate mud is largely bioclastic in origin, 

whether originally mainly aragonitic (as described in 

Cloud, 1962, from the Bahamas) or calcitic in composition (Davies, 1970, Shark Bay, Western Australia). The 

only known inorganic precipitation of CaCOa is in the 

lagoons of Abu Dhabi (Kinsman and Holland, 1969). 

Ancient micrites usually have a porosity of about 1 

percent, although chalks have porosities as great as 40 

percent. The process by which recent carbonate mud 

with porosities in excess of 50 percent becomes lithified 

is a matter of some complexity. 

Although Wolfe (1968) demonstrated a 30-percent 

reduction in volume during the diagenesis of the Chalk 

of Northern Ireland, evidence of compaction is generally lacking in limestones. This would then imply that 

to complete the process of lithification, the CaCOa has 

an external source. It is, however, difficult to visualize 

this process because the low porosity micrites ( ~ 1 percent porosity) have a permeability of about 0.01 millidarcies, and even the high-porosity chalks have low 

permeabilities (less than 10 mD). These figures suggest 

that very small amounts of carbonate-rich interstratal 

solutions pass through the carbonate mud. The most 

probable origin of excess CaCOa is, in our opinion, 

within the carbonate mud itself-a process of solution 

and almost immediate redeposition that allows reduction of the original volume without obvious signs of 

compaction. This process probably is most active in 

rocks with an original high aragonite content. In contrast, rocks composed originally of low-Mg calcite (for 

example, chalk is composed essentially of skeletons of 

coccolith debris) have little tendency to this small-scale 

solution, and in general the porosity tends to be retained during geological time. 

DOLOMITE 

The double carbonate of calcium and magnesium 

(dolomite) contrasts with calcium carbonate in having 

only one crystallographic form (euhedral/anhedral 

rhombs). As mentioned in the previous section on ~~calcite", the conversion of metastable aragonite or highMg calcite to stable low-Mg calcite commonly causes 

ground water to become enriched in calcium carbonate; 

this calcium carbonate is subsequently deposited as 

sparry calcite cement. Dolomite, except for the relatively rare process of dedolomitization, is not subject to 

large-scale solution, and dolomite-rich interstitial waters are rare. These chemical and mineralogical factors 

together with the absence of dolomite as a primary 

constituent of marine skeletons explain the paucity of 

diagenetic information obtainable from dolomite fabrics. 

The major source of variability in dolomites is in the 

degree of nonstoichiometry. Ideally, dolomite has a 1:1 
DOLOMITE 23 

ratio of Ca!Mg, but when ferrous iron is incorporated 

into the dolomite lattice, it substitutes more readily for 

Mg2+ ions than for the Ca2+ ions. Katz (1971) reported 

that calcian-ferroan dolomites averaging Ca58Mg35 

Fe2+ 7(C03) 100 are common in the Mahmal Formation of 

southern Israel, and in 1968 he suggested that these 

non-stoichiometric dolomites are particularly prone to 

dedolomitization. Another nonstoichiometric form, but 

one that does not incorporate foreign ions into the 

dolomite lattice, is protodolomite, which contains about 

10 mole percent of excess CaC03 in the lattice 

(Goldsmith and Graf, 1958). Protodolomite, of composition CassMg44, is deposited in the Coorong Lagoon of 

South Australia (Alderman and Skinner, 1957) and is 

common in the recent dolomites of the Arabian Gulf 

sabkhas (Kinsman, 1966). Illing, Wells, and Taylor 

(1965) record recent dolomite rhombs of the size 1-5 

micrometres from Qatar in the Arabian Gulf. In spite of 

their comment that they were dealing with ~~true 

dolomite," their data showing the existence of dolomites 

with a Ca:Mg ratio up to 55:45 are comparable to the 

protodolomites of the Coorong Lagoon (Alderman and 

Skinner, 1957). Wood and Wolfe (1969) have described 

Jurassic-Cretaceous rocks from Abu Dhabi that were 

deposited in an environment similar to those from 

Qatar, but the dolomite rhombs average 50 micrometres 

in size, suggesting that extensive grain growth has 

taken place during diagenesis-a process that could be 

associated with the loss of Ca2+ from the original 

protodolomite. In general, protodolomites probably lose 

their excess Ca2+ and gradually revert to the stoichiometric composition. 

DOLOMITE 

Dolomite is best subdivided on the basis of its grain 

size. Following the usage of Illing, Wood, and Fullor 

(1967), the dolomites are subdivided into 

macrodolomite, which has an average grain size larger 

than 30~-tm, and microdolomite, which has an average 

grain size of smaller than 30 ~-tm. As discussed in the 

section on the ~~Origin of Dolomites", the distinction 

between syngenetic and diagenetic dolomites is difficult 

to determine, but the average grain size is one factor 

that helps. 

As described in the section 69A-4/4K, Old Man 

Creek, the Plunge Creek section (70A-4/5) has the 

largest amount of dolomite in the total section (33 percent) as compared with 9 percent in the western Sadlerochit Mountains (69A-1) and 15 percent in the east 

Sadlerochit Mountains (68A-4A/4B). The dolomite is 

concentrated in all three sections of the Alapah Limestone, and rare amounts are present in the dominant 

grainstone rock type of the Wahoo Limestone. 

In the Plunge Creek section, the lower of two predominantly dolomite units (330-720 ft) is homogeneous unzoned macrodolomite with rare intervals of microdolomite; the upper unit (918--1,630 ft), which terminates the Alapah Limestone, is dominantly macrodolomite interbedded with wackestone and packstone 

(fig. 2). The macrodolomite rhombs of the lower unit are 

often outlined in hematite, and toward the top all interrhombic spaces are filled with dark clay. Iron-rich cores 

are sporadically apparent in the rhombs. Dolomite is a 

common accessory in the limestone, and at those places 

where it occupies less than 25 percent of the total volume, the grain size tends to be coarser. 

In the western Sadlerochit Mountains section 

( 69A-1) five thin discrete units of 10-20 feet of dolomite, 

largely microdolomite, are scattered through the 

Alapah Limestone. No thick units of dolomite exist in 

this section although the suggested depositional environment of the uppermost unit of the Alapah Limestone 

is a restricted platform, similar to that suggested for the 

uppermost dolomite unit in the Plunge Creek section. 

Accessory macrodolomite rhombs are common. They 

are usually outlined with hematite, and some have an 

iron-rich core with iron-poor rims. 

In the eastern Sadlerochit Mountains section 

(68A-4A/4B), the total section contains 15 percent of 

dolomite concentrated in two major units of the Alapah 

Limestone. The lower unit (360-520 ft) consists of 

homogeneous macrodolomite with an absence of zoning 

in the individual rhombs. The upper unit (750-820 ft), 

which terminates the Alapah Limestone, consists of a 

microdolomite with patches of chert. Algal mats have 

been recorded in the outcrops of this unit. Scattered 

discrete horizons of microdolomite with remnants of 

bryozoan and crinoid debris occur in the Wahoo Limestone. Patches of iron-rich macrodolomite in a microdolomite host (pl. 3, fig. 9) represent a later stage 

replacement of a high-Mg bioclast such as a crinoid 

plate. 

In the Old Man Creek section (69A-4-4/K), a large 

proportion of the rocks are dolomite, but as mentioned 

in the section on ~~69A-4/4K, Old Man Creek," they have 

been subjected to intense recrystallization. Microdolomite (some of which is laminated) is the major rock type, 

and it is particularly well developed at the top of the 

Alapah Limestone (940-1,032 ft) and toward the base 

(0-215 ft). The macrodolomites tend to be sporadic thin 

beds, and many individual rhombs have cloudy cores 

with clear rims. 

ORIGIN OF DOLOMITES 

The origin of dolomite, long a matter of dispute, has 

been largely resolved since the advent of X-ray spectroscopy and detailed fieldwork in areas of recent dolomite formation such as the island of Bonaire in the 

Netherlands Antilles and the coastal flats (sabkhas) of 

Abu Dhabi. The source of the excess Mg2+ ions needed to 
24 DIAGENESIS AND STRATIGRAPHY OF THE LISBURNE GROUP LIMESTONES NORTHEASTERN ALASKA 

produce dolomite is now accepted as interstitial brines 

in which the Mg/Ca ratio has been increased. 

Whether or not primary dolomite exists is largely a 

semantic argument regarding the definition of ~~primary." The earliest formed dolomite is usually referred 

to as syngenetic, that is, formed prior to lithification as a 

dolomite mud. The production of the high Mg-2+ ratio is 

produced in areas where evaporation exceeds precipitation. These heavy brines then seep down into the underlying sediments, which become progressively dolomitized (Adams and Rhodes, 1960; Deffeyes and others, 

1965). 

Syngenetic and diagenetic dolomites are certainly 

the most important types, although detrital and 

epigenetic dolomites are also described in the literature 

(Friedman and Sanders, 1967). The distinction between 

syngenetic and diagenetic dolomites is, however, often 

difficult to make. It is possible to establish criteria for 

each type, but they are by no means mutually exclusive. 

Syngenetic dolomite 

1. Very fine grain size ( ~ 10~-tm), which can be 

increased by a process of grain growth. 

2. Homogeneous nature of the individual crystals 

and the rock itself. 

3. Association with sulfate minerals or with evidence of intertidal environments (algal mats). 

4. Restriction to one horizon, commonly at the end 

of a depositional cycle. 

Diagenetic dolomite 

1. Medium to coarse grain size. 

2. Individual crystals; often zoned and have more 

than one phase of dolomite formation. 

3. Partially dolomitized rocks are common, and the· 

dolomite may be in the lime-mud matrix 

rather than in the grains themselves. 

4. Interdigitation with nondolomitic carbonate 

rocks. 

For the Lisburne Group of the Sadlerochit Mountains, in particular, the most reasonable conclusion is 

that both syngenetic and diagenetic dolomites exist. 

The syngenetic type is associated with the top of the 

dolomite unit that commonly occurs at the top of the 

Alapah Limestone and below the shallow-water grainstone of the Wahoo Limestone. 

A supratidal-intertidal environment has already 

been postulated for syngenetic dolomites from the occurrence of algal mats. The dolomites that fulfill the 

criteria for a diagenetic origin tend to occur below those 

of probable syngenetic origin and could well have been 

formed by some form of reflux of heavy brines. As discussed in the section on uchert", the dolomite that occurs in chert is thought to be associated with the development of chert and is independent of normal 

dolomitization processes. Epigenetic dolomite is probably represented by central dolomite fillings of fractures 

lined on both sides with quartz (pl. 3, fig. 2) and by the 

development of dolomite in bitumen restricted to planes 

of stylolites (pl. 12, figs. 1, 2). Muller and Tietz (1971) 

illustrated an example of the dolomitization of earlyphase sparry calcite rim cement that leaves the equant 

second-phase sparry calcite unaffected. The bioclastic 

grainstone section (pl. 4, fig. 4) from the western Sadlerochit Mountains may be another example of this 

phenomenon. 

ZONING IN MACRODOLOMITES 

The zoning of dolomite crystals, similar to the zoned 

macrodolomites of the Lisburne Group, has been discussed in detail by Katz (1971). He suggests that the 

zoning represents growth stages of the rhombs and that 

the variation in composition of each zone reflects ~~compositional changes in the interstitial brines with respect to their dissolved Ca2 +, Mg2+ and Fe2 + contents 

during dolomite crystal growth." 

Although zoning is common in the Lisburne Group 

macrodolomite, it is difficult to be sure of the original 

mineralogical nature of each of the zones. Figure 19 

illustrates a possible origin of the macrodolomite in the 

Lisburne Group, although it must be emphasized that 

iron-rich cores (recognizable from a potassium ferricyanide stain) are by no means ubiquitous. The first 

stage is the formation of accessory iron-rich 

dolomite-probably in carbonate mud trapped within 

the dominantly bioclastic grainstones and prior to any 

sparry calcite cementation (Stage 1). The ferroan dolomite is nonstoichiometric and contains excess calcium 

relative to magnesium. This type of dolomite is particularly prone to dedolomitization because of either the 

increase in free energy of calcian dolomite relative to 

normal dolomite or the ease of replacing calcium ions 

through the intercrystalline boundaries (Katz, 1968). 

When the calcian-rich zones have been replaced by 

calcite (Stage 2) or with the approach of ferroan dolomite to a stoichiometric composition, it is probable that 

the excess of iron in the calcite lattice will then be 

expelled to the rim of the dolomite rhombs. This expelled Fe2+ is in the form of ferric oxide (Stage 3). A second 

stage of dolomite (Fe free) is sometimes deposited 

around the original rhomb and in optical continuity 

with it (Stage 4), that is, the external-source dolomite of 

Murray (1960). The core of the dolomite rhomb is then 

susceptible to solution as shown by the existence of 

iron-stained rhombs with a patchily dedolomitized rim 

but either a void or a corroded non-Fe dolomite core 

surrounded by a void umoat." Solution almost certainly 

occurs after the pore-fill stage of sparry calcite deposi-
DOLOMITE 25 

3. 

2. 

~Calcite 

~ 

Dedolomitization of the iron-rich 

zones of the rhomb. Both calcite 

and dolomite in optical continuity 

1. 

~ - • ••• • • ••• 4 •• • ~ • 

. . ·: ~}~-:~·"/{"·: .. 

Expulsion of the excess FeH 

from the calcite lattice upon 

dedolomitization. Now in the 

form of Fe203 

Macrodolo~~~ for~~~-i~ carbonate 

mud trapped within grainstone. 

Iron-rich dolomite zoning parallel 

to rhomb-faces toward rim 

5. 

4· Second-stage iron- free 

dolomite 

/i4llV 

Second-stage iron-free dolomite 

formed sporadically in optical 

continuity with original rhomb 

!STAGES 14 PRE SPARRY CALCITE PORE-FILL) 

!STAGE 5 POSTWTE PORE-FILL) 

/!Ql/ a Solution of iron-free dolomite in core of rhomb 

to form: (a) central voids, or (b) corroded 

dolomite core with a void "moat'" surrounding it 

FIGURE 19.-Sequence of diagenesis in zoned iron-rich dolomites. 

tion because infilling of voids formed by solution has not 

been observed. 

This interpretation differs from that given by Katz by 

suggesting that the hematite-rich outer zone is related 

to the expulsion of Fe2+ from original ferroan dolomite 

zones and not, as suggested by Katz, to direct precipitation directly from interstitial solution upon growing 

dolomite crystals. The main factors supporting this conclusion are that (1) the hematite zones are developed on 

the outer margin of the first phase of dolomite formation, and (2) hematite is particularly well developed 

when zones of dedolomitization are apparent. 

DEDOLOMITE 

A characteristic of dolomite as an accessory mineral 

is its occurrence as discrete rhombic crystals. Since the 

widespread use of the organic Alizarin Red S stain 

(Friedman, 1959) has facilitated the distinction between calcite and dolomite, several authors have described the replacement of such dolomite rhombs by 

calcite (Shearman and others, 1961; Schmidt, 1965; 

Bausch, 1965; Evamy, 1967; Armstrong, 1967; Mattavelli and others, 1969). 

Dedolomites are found in the Lisburne Group of the 

Sadlerochit Mountains. They occur in two major types. 

The most common type is the selective replacement of 

dolomite in planes parallel to and toward the outer 

margin of the original rhomb faces (see pl. 5). The most 

common example of this type is a discrete dolomite 

rhomb outlined in hematite with one thin plane of calcite parallel to the rhomb faces. In some rhombs the 

interiors are dolomite, but in others the cores are voids 

(see pl. 4, figs. 4, 5, 6). 

In the example in the frontispiece and on plates 4 and 

5, the diagenetic history is apparently more complicated. The dedolomitized calcite is developed in a series 

of planes parallel to the rhomb faces and is concentrated 

toward the outer edge. The calcite is not in optical continuity with the original dolomite, and its extinction is 

patchy. The variation in the orientation of the calcite is 

noticeable in the difference in the orientation of the 

twin planes; these orientations could be secondarily 

induced. The iron-poor original dolomite rhomb extinguishes in quadrants and is in optical continuity with 

adjacent overgrowths of dolomite. The terminations of 

the overgrowths are parallel to the plane intersection of 

the original rhomb faces. Patches of hematite occur on 

the edge of the rhomb. 

Simple, partly dedolomitized rhombs of this type 

occur in a zone (550-558 ft) of the Plunge Creek section 

where not only is a zone of calcite developed toward the 

outer edge of the rhomb, which is outlined in hematite, 

but the outer margin is etched by the adjacent sparry 

calcite cement. 

Other examples of this type of dedolomitization were 

found in the western Sadlerochit Mountains section 

(69A-1). The coarse-zoned dedolomites of plate 5 occur 

between 60-80 feet. Between 445-465 feet (pl. 4, fig. 5) 

the rhombs outlined in hematite have a single zone of 

calcite toward the outer margin of the rhomb, and in 

addition the center of the original rhomb is now void. 

The second type of dedolomitization is the spotty replacement of dolomite rhombs by calcite. The arrangement of the calcite spots is not apparently related to the 

structure of the individual rhombs. The outer margins 

of the rhombs are commonly corroded by adjacent 

sparry calcite. This second type of dedolomite is restricted to the Old Man Creek section (69A-4/4K) (pl. 4, 

fig. 7). 

CAUSES OF DEDOLOMITIZATION 

Von Morlot (1848) suggested that the conversion of 

dolomite to calcite possibly resulted from the reaction of 

calcium sulfate-bearing solutions on dolomite, that is, 

CaCOa · MgCOa + CaSQ4 = 2CaC~ + MgS04. 

Tatarskiy (1949) suggested that this is a valid process 

but found it restricted to outcrops. 
26 DIAGENESIS AND STRATIGRAPHY OF THE LISBURNE GROUP LIMESTONES, NORTHEASTERN ALASKA 

De Groot (1967), however, has shown from experiments that dedolomitization can be achieved by a high 

Ca2+ M~+ ratio, and Fritz (1967) suggested that dedolomitization is probably taking place in the German 

Jura at the present day. Katz (1968, 1971) considered 

that calcian dolomites are particularly susceptible to 

dedolomitization. In the case of the Mahmal dolomites 

of Israel, Katz suggested that dedolomitization takes 

place during intervals of dolomite growth. Even if dedolomitization is accepted as being restricted to surface 

outcrops, it is not normally known whether the dedolomites are of recent or ancient origin. Schmidt (1965) and 

Braun and Friedman (1970) have used zones of dedolomite as possible indicators of unconformity surfaces, 

but none of the examples cited by them prove that the 

dedolomitization was not modern. 

The dedolomite in the Lisburne Group of the western 

Sadlerochit Mountains section (69A-1) (pl. 5) can only 

be explained in terms of a dedolomitization process 

operative prior to formation of secondary dolomite 

overgrowths. If ancient dedolomitization is accepted as 

a clue to an unconformity surface, then the dedolomite 

of 60-80 feet in section 69A-1 is probably an example. 

Correlation on the basis ofMamet's foraminiferal zones 

of this zone of dedolomitization in the western Sadlerochit Mountains section (69A-1) ties in with the dedolomitization zone from 550-558 feet in the Plunge 

Creek section (70A-4/5), that is, within Zone 16i of the 

Chesterian Series. This correlation is an added indication that both these dedolomitization zones could be a 

product of meteoric waters with a high Ca2+ I Mg2+ 

ratio produced during a period of emergence. There is no 

evidence that the upper zone of dedolomitization in 

69A-1 (that is, 455-465 ft) is other than a product of 

recent meteoric waters. Indeed the preservation of 

intra-rhombic voids alone would suggest that solution 

of the dolomite took place after the formation of the 

sparry calcite cement. 

The spotty dedolomite common in the Old Man Creek 

section (69A-4/4K) almost certainly has a different 

origin. As described in the section on ((69A-4/4K, Old 

Man Creek" the limestones of section 69A-4/4K have 

been subjected to extensive metamorphism attributed 

to the emplacement of the Mount Michelson pluton. 

This metamorphism has resulted in widespread grain 

interpenetration and solution of calcite. The dedolomitization would then probably be a result of the 

resulting interstitial fluids with a high Ca 2+ /Mg 2+ 

ratio. 

DISTRIBUTION OF IRON 

Although the presence of trace cations (especially 

ferrous iron) in both dolomite and calcite is well known, 

it is not normally detectable in thin section. Iron more 

commonly enters the dolomite lattice, and the end 

member is the iron-calcium carbonate, ankerite, where 

all the magnesium ions have been replaced by ferrous 

iron with a consequent increase in both refractive index 

and birefringence. 

Evamy (1963, 1969) and Evamy and Shearman (1965, 

1969) not only described a reliable and stable stain for 

locating iron in the carbonate lattices but also used this 

distribution to draw petrogenetic conclusions. The preferred stain for ferrous iron is 0.5 percent saturated 

potassium ferricyanide in a 0.2 percent solution of hydrochloric acid, which provides a blue C(Turnbull's 

blue") pigment. The intensity of the stain is in direct 

proportion to the concentration of ferrous iron, other 

factors being equal. This potassium ferricyanide stain 

was used regularly in the study of the Lisburne Group. 

More recently, Freeman (1971) has used cathodoluminescence to distinguish between different phases of 

cement that possess more subtle variations of Fe2+ 

content than is traceable by the potassium ferricyanide 

stain. Fd~+ IN CALCITE 

The distribution of iron in the calcite of the Lisburne 

Group appears to follow a uniform sequence. The debris 

(bioclastic, oolitic, and pelletoid) appears to be essentially free of iron, and this is also true of any interstitial 

mud (micrite). Two generations of sparry calcite can, 

however, sometimes be clearly separated on the basis of 

their iron content. The first phase of sparry calcite forms 

either as iron-poor syntaxial overgrowths around 

echinoderm fragments or as fringes around other bioclasts or oolites. Evamy and Shearman (1969) clearly 

demonstrated that the overgrowths on echinoderm 

crystals are developed as iron-poor spires of crystals in 

the direction of the c axis of the original grain. The 

serration of the outline of the first-phase sparry calcite 

is a result of the initiation of cementation only on the 

fragment surface between the pore-canal openings. 

Overgrowths tend to be restricted to those parts of the 

original crystal that allow growth parallel to the c axes. 

Grain relations shown on plate 9, figure 2, suggest that 

syntaxial overgrowths on echinoderm debris are a result of the pushing aside of original detritus rather than 

being a product of replacement. The first-stage ironpoor sparry calcite overgrowths on pelecypod fragments 

and oolites also tend to be of irregular prismatic outline 

elongated at right angles to the grain surface. In contrast, the first-stage cement is not noticeable around 

bryozoan fragments. The introduction of second-stage 

sparry calcite represents the final phase of obliteration 

of the original pore space of the grainstones. The calcite 

occurs as generally equant crystals, the orientation of 

which ignores the shape of the pores. Although variable, this second-phase cement tends to be rich in iron, 

but in any one thin section no zoning of the iron content 
DISTRIBUTION OF ffiON 27 

was apparent; this lack of zoning contrasts with· that 

described by Evamy and Shearman (1969). The concentration of iron in the second-phase sparry calcite 

cement is at a maximum in the coarse grainstone units 

of the Lisburne Group, especially in the oolite units of 

the Wahoo Limestone. Although it has been observed 

that the lime mud (micrite) generally shows no evidence 

of the presence of Fe2+ at 990 feet in the eastern Sadlerochit Mountains section (68A-4A), the micrite adjacent to some patches of chert is particularly enriched in 

ferrous iron (pl. 8, fig. 4). This suggests that the zone of 

Fe 2+ enrichment could represent concentrations of all 

the iron originally in the replaced limestone. 

The time relationship between the two stages of calcite cementation is of importance. There is no evidence 

of corrosion prior to stage two or any suggestion of a 

plane of inclusions that could define the termination of 

stage one. Nevertheless, the change of habit coincident 

with the general increase in iron content in the second 

stage suggests some time lag between the two stages of 

cementation. Enfacial junctions (Bathurst, 1971, p. 

434) are common between the iron-rich and iron-poor 

phases of cementation in the Lisburne Group and could 

provide support for a time difference between the stages 

of cementation. An example of the early fringe, ironfree, first-phase calcite cement growing perpendicular 

to the oolite surface with the absence of second-stage 

cement is illustrated in Illing, Wood, and Fuller (1967, 

fig. 1F) from the oil-bearing Minagish Oolite ofKuwait. 

Fe2+ IN DOLOMITE 

As described in detail in the previous section, the 

dolomite in the Lisburne Group is of at least two distinct 

generations. The early first stage is often iron rich, in 

contrast to the sparry calcite. Some of the samples of 

this phase are homogeneously rich in iron and remain 

rich in iron with time (60ft, 69A-1); they occur as the 

iron-rich and ~~dusty" core to dolomite rhombs (pl. 4, fig. 

8) or as corroded homogeneous iron-rich dolomite (pl. 4, 

fig. 2). More common, however, is the presence of clusters of iron-oxide-rimmed rhombs that appear to be 

zoned and probably represent original-zoned ferroan 

dolomite that has readjusted to its lattice to expel the 

contained iron. This zoning is particularly noticeable 

with zones of dedolomitization parallel to the rhomb 

faces ( +60 ft, 69A-1). 

The second-stage dolomite occurs either as an ironfree rim around the ferroan dolomite core or as iron-free 

overgrowths developed along the plane of intersection 

of the rhomb faces. This second stage postdates any 

phase of dedolomitization (pl. 5). A possible third phase 

of iron-free dolomite occurs in section 69A-1 where 

veinlets crosscutting the host rock are partly filled with 

dolomite. 

TABLE 3.-Habit and iron content of sparry calcite cement and dolomite 

Mineral Stage Habit Fe content 

Calcite 1st Fibrous at right angles to grain Poor. 

margin or syntaxial overgrowth 

parallel to c axis on echionoderm 

plates. 

2d Subequant independent of pore Rich. 

shape, obliterates all primary 

pore space. 

Dolomite 1st Corroded grains or as "cloudy" Rich. cores to rhombs. 

2d External part of rhomb, free from Poor. 

inclusions, or as overgrowths on first-stage rhombs. 

ENVIRONMENTAL SIGNIFICANCE 

Table 3 summarizes the preceding discussion and 

emphasizes the existence of at least two phases of formation of both sparry calcite cement and dolomite. The 

first phase of sparry calcite is free of iron, while the 

second stage is rich in iron; in contrast, the dolomite has 

a first phase that is rich in iron with an iron-poor second 

stage. Evamy (1969) has stated from the work of 

Castano and Garrels (1950) and Garrels and Christ 

(1965) that ferrous iron is only stable during carbonate 

sedimentation under reducing conditions that occur 

dominantly below the water table. In addition, Evamy 

suggested that any ferrous iron incorporated into carbonate lattices beneath the water table is then stable 

through geological time. If this hypothesis is accepted, 

an environmental criterion can be established for ferroan calcites and dolomites, but, conversely, no criterion exists for interpreting the environmental formation 

of iron-free carbonate rocks. The environmental implications of the distribution of iron in the carbonate rocks 

of the Lisburne Group are: 

1. The iron-poor calcite fringe cement was probably formed before the original aragonite of 

oolites or pelecypod fragments or the high-Mg 

calcite of echinoderm debris changed to stable 

low-Mg calcite. The fringe cement of the oolites and pelecypods probably has a common 

origin with the syntaxial overgrowths on 

echinoderm plates. It was suggested in the 

previous section that this iron-free first-phase 

cement originated by direct precipitation of 

CaCQa from supersaturated sea water. 

2. The second-stage equant iron-rich pore-filling 

crystals of calcite (drusy-calcite of Bathurst, 

1958) would, if the hypothesis ofEvamy (1969) 

is accepted, be formed in the reducing environment beneath the water table, probably 

after the first-stage iron-rich dolomite. This 

sequence may indicate an external source of 

both calcium and carbonate ions, possibly 

CaCOa-rich waters produced by the large-
28 DIAGENESIS AND STRATIGRAPHY OF THE LISBURNE GROUP LIMESTONES, NORTHEASTERN ALASKA 

scale solution of aragonitic components (as 

outlined by Bathurst, 1964, 1966). 

The second-stage calcite cement ubiquitously fills the pore space in the Lisburne 

Group. To generate this vast amount of cement from internal sources, it would be necessary to dissolve a great quantity of aragonite. 

This process takes place preferentially in 

fresher waters (Cloud, 1962) and, as noted by 

Illing, Wood, and Fuller (1967, p. 498), could 

suggest that the Lisburne Group was deposited in an epicontinental sea of repeated uplift and downwarp. 

3. The first-stage dolomite was rich in iron and 

commonly zoned (Katz, 1968). The original 

composition of dolomite is a function of the 

chemistry of the pore waters, and the zoning 

probably reflects their piecemeal formation. 

Commonly the iron-rimmed dolomites occur 

as clusters, the margins of which are abruptly 

terminated by the second-stage sparry calcite; 

the calcite having no relationship to the 

rhomb outlines. This fact suggests that the 

first-stage dolomite was formed from a local 

source (Murray, 1960) ofmagnesium ions as a 

replacement of original carbonate mud beneath the water table prior to introduction of 

the second-stage sparry calcite cement. 

4. The second stage of dolomite formation probably 

represents replacement of calcite by the ((distant sources" of magnesium (Murray, 1960). 

There is probably a time gap in the development of the second-stage dolomite after formation of the iron-rich core, but no criteria are 

available to suggest its duration. The absence 

of inclusions in the second-stage dolomite 

suggests that it formed by the physical creation of space during crystallization rather 

than by replacement. 

CHERT 

The structure of the abundant chert in the Lisburne 

Group is generally microscopically uniform, but from 

its original locus, two types can be distinguished-matrix (intergranular) chert and intragranular chert. 

FABRIC 

Matrix chert.-This chert tends to occupy the intergranular space between bioclasts, usually echinoderms 

or bryozoans, which are only marginally replaced (pl. 8, 

fig. 5). The blebs of matrix chert usually have an abrupt 

margin with the host limestone, but it is clear that the 

bedding is commonly displaced around the bleb, indicating either primary accumulation or postdepositional 

development prior to lithification. In contrast to the 

intragranular chert, the contained fragments of 

echinoderm debris show no evidence of concentration of 

silica within the plates. 

Intragranular chert.-This chert type (fig. 20) is preferentially developed in echinoderm plates (pl. 9, figs. 

1-6) or fibrous pelecypods (pl. 8, fig. 2). It occurs as a 

partial replacement or as preserved ((ghost" structures. 

Plate 10, figure 6, clearly shows the chert formed by 

the preferential replacement of the bioclastic debris of 

the Lisburne Group. In the upper part of the specimen, 

the crinoid fragments are yellow and stand out in relief 

above the calcareous but nonsiliceous matrix after acid 

etching. At the base of the core specimen, crinoid debris 

set in a similar matrix is preserved in sparry calcite. 

Many echinoderm plates (pl. 9, figs. 1-6) and fibrous 

pelecypods are partly replaced by chert, yet other parts 

of the enclosing rock contain no silica whatsoever. A 

penumbra in which the pore structure of the 

echinoderm plate has been destroyed and which appear 

to be composed of an intimate admixture of silica and 

calcite commonly surrounds the silica blebs. The other 

grains are affected by the chertification only where the 

LL. 

0 

LlJ 

(/) 

<( 

LlJ 

a: 

(..) 

z 

UJ 

z 

0 

1-

(1.) 

z 

<( 

a: 

(!) 

....._UJ 

UJZ 

zo 

(1.)~ 

~§ 

~(._) 

U<( 

~~ 

UJ 

z 

0 

1-

(1.) 

0 

:::> 

::2 

E i 

I 

I The diagenetic end prodB I 

uct of this rock type 

I is banded chert I 

sc xxxxx I 

E I 

I 

/ The diagenetic end prodB ~;;';%:;:(C:~?:;:X;0'~ uct of this rock type 

! is chert/dolomite 

i M (-%;:;::~~;;;;w:;;;;;;,wm/%:~ I 

The diagenetic end prodM ~~,'~ >~~;::~-;.;::-,:;< ~: /r'/:Y:::/::/1(("/;-<;'~/ ~ uct of this rock type 

is dolomite 

----TIME----

EXPLANATION 

E 8 

Echinoderms Bryozoans 

Dominant faunal elements 

sc M 

Sparry calcite Calcite mud (micrite) 

Dominant intergranular elements 

xxx, time of introduction 

of sparry calcite 

'%&~ 

Chalcedony Dolomite 

FIGURE 20.-Diagenetic history oflimestones containing intragranular chert. 
CHERT 29 

echinoderm plates and pelecypods are completely replaced. If the original interstitial material was sparry 

calcite cement, this cement is also eventually replaced 

by chert, but any original carbonate mud is preferentially replaced by dolomite rather than chert (pl. 8, figs. 

7, 8). 

TIME OF ORIGIN 

The photomicrographs of plate 7 confirm the early 

diagenetic formation ofintragranular chert and provide 

a framework from which a large part of the sequence of 

diagenesis of the Lisburne Group can be deciphered. 

The single anhedral crystal of sparry calcite in the 

center of the field of view contains a line of micrite 

inclusions. This crystal is interpreted as an original 

echinoderm plate in which the original pore outlines are 

still preserved; the plate is bounded by the remains of a 

micrite envelope, and the whole is then encompassed by 

a syntaxial overgrowth. The micrite envelopes (pl. 9, 

figs. 3, 8) are common features on bioclasts and are 

believed to form immediately after death of the organism by the intersecting surface burrows of algae 

(Bathurst, 1966). At approximately this stage, silica 

began to nucleate in the pore space of the echinoderm 

plate and formed approximately equidimensional crystallites. 

The first stage of sparry calcite then formed as a 

syntaxial overgrowth around the original echinoderm 

fragment, leaving a line of micrite inclusions as the only 

remnant of the micrite envelope. The absence of inclusions in the syntaxial overgrowth and the fracture of a 

bryozoan frond against an adjacent foraminifer suggest 

that this overgrowth was developed in a void with complementary pushing aside of any accessible carbonate 

grains or mud. 

The next stage of diagenesis was the development of 

fibrous silica extending from the original spotted nucleus into the syntaxial overgrowth of sparry calcite. 

The final stage was the second phase of sparry calcite 

cementation with radiaxial and equant texture. 

This sequence of diagenesis clearly demonstrates 

that the original silica nucleation within the 

echinoderm plates took place at a very early phase of 

diagenesis, probably before lithification. The extent of 

subsequent chertification is probably a function of the 

local availability of silica in the pore waters. 

MODE OF ORIGIN 

It is obvious that the intragranular cherts are formed 

by replacement of an original limestone with the silica 

first nucleating in the plates of echinoderms. However, 

the evidence for the origin of matrix chert is ambiguous; 

feasible hypotheses are: either preferential replacement of the matrix by silica or the presence of an original siliceous deposit. 

If both the intragranular and matrix cherts originated by replacement of calcium carbonate by silica, it 

is difficult to reconcile both types being formed in the 

same depositional regime. Accepting the welldocumented preferential replacement of echinoderm 

plates in the intragranular cherts, it is necessary to 

imply that the matrix chert was originally a primary 

deposit ofbiogenic origin. This kind of origin would then 

allow adjacent pore fluids to be strongly enriched in 

silica, which could then form intragranular cherts by 

replacement of bioclastic limestones. 

SOURCE OF SILICA 

Because of the low solubility of silica in sea water, the 

process of derivation of the opaline silica now forming 

vast thicknesses of chert and flint in the sedimentary 

column has been a matter of considerable argument. 

It is widely accepted (MacKenzie and Garrels, 1966) 

that the bulk of the silica supplied to the oceans reacts 

with bicarbonate and other cations to form reconstituted clay minerals, thus maintaining a low concentration of silica in sea water. However, Calvert (1968) has 

made a convincing case for the primary biological control of the silica content of sea water, and he suggested 

that the reconstitution of clay minerals is probably a 

diagenetic reaction. 

Diatoms, Radiolaria, and sponges are the main organisms with siliceous skeletons (Siever, 1957; Pittman, 1959). Krauskopf (1959) suggested that the siliceous skeletons of these organisms are protected by 

organic films which decompose after death and permit 

slow dissolution. Solution of the skeletons produces interstitial waters containing more than four times as 

much silica as normal sea water (Siever, 1959) and very 

close to saturation (Calvert, 1968). Interstitial waters of 

sediments from the South Pacific have been shown (Arrhenius, 1963) to have silica contents ranging from 6 to 

788 ppm. 

Calvert (1968) has shown that at the present day the 

Antarctic belt of siliceous oozes accounts for 80 percent 

of the current silica presently being removed from the 

oceans. He also suggested that the band of siliceous 

sediment in the subarctic Pacific was developed as a 

result of high biological productivity in an area of 

oceanic upwelling, rich in nutrients. The transfer of 

silica from water to newly deposited sediment is probably continuous, and opaline silica is released from the 

tests of siliceous organisms within the developing 

sedimentary accumulation. In spite of references in the 

literature to primary silica gels (Bissell, 1959; Maxwell 

and others, 1970, p. 442), there is no evidence for the 

presence of silica in any form other than undissociated 

monomeric silicic acid in true sol uti on at normal pH 

(Krauskopf, 1959; Siever, 1959). 
30 DIAGENESIS AND STRATIGRAPHY OF THE LISBURNE GROUP LIMESTONES, NORTHEASTERN ALASKA 

Thick cherts of Eocene age containing abundant 

radiolarian debris have been found by the Deep Sea 

Drilling Project throughout the North Atlantic (Peterson and others, 1970) and in the South Atlantic (Maxwell and others, 1970). Consolidated Eocene chert from 

Hole SA of the Deep Sea Drilling Project on the northeast flank of the Bermuda Rise contains as much as 80 

percent recognizable radiolarian remains (Wood, 1969). 

In contrast, Radiolaria are preserved as sparry calcite 

in lime mudstone in Hole 5A on the west flank of the 

Hatteras Abyssal Plain (Wood, 1970). The replacement 

of originally siliceous organisms by calcite, as also observed in the Cenomanian limestone ofLurestan, Iran, 

confirms that the silica of the original skeletons was 

released into the host sediment after deposition. 

Ernst and Calvert (1969) described a stratigraphic 

sequence passing from diatomite to porcellanite to chert 

from top to base of the Monterey Formation of California, and they suggested that the silica has been progressively recrystallized down the section. The rate of recrystallization is considered to be relatively constant, 

and Ernst and Calvert showed that, in the presence of 

stagnant pure connate water, the Monterey porcellanite (cristobalite) should recrystallize to chert (quartz) 

in 180 million years. Mizutani (1970) confirmed this 

transition by experimental investigation under hydrothermal conditions. 

The Eocene cherts of the Atlantic (Peterson and 

others, 1970, p. 422) are dominantly cristobalite in 

composition, and the radiolarian remains, as mentioned 

above, are well preserved. These rocks are approximately 50 million years old, and their mode of preservation would fit into the Ernst and Calvert hypothesis. 

The rare preservation of silica-bearing organisms in 

older cherts (especially those of Paleozoic and older age) 

is probably a function of their position at the end of the 

recrystallization sequence and in no way reflects an 

inorganic origin. 

Evidence for the source of silica in the Lisburne 

Group is scanty, but examples of sponge spicules preserved in silica (pl. 8, fig. 1) or in calcite or dolomite (pl. 

8, fig. 3) do exist. The specimens are composed of closely 

packed sponge debris, and similar accumulations could 

represent the local source of silica for the matrix chert. 

The common occurrence of cracks (pl. 9, fig. 5) within 

and surrounding the chert bodies can be attributed to 

the progressive desiccation of porcellanite. 

The nucleation of the ((intragranular chert" started, 

as has been previously mentioned, in the pore spaces of 

plates of echinoderms that were originally composed of 

a single crystal ofhigh-Mg calcite (Donnay and Pawson, 

1969). These plates have a spongelike internal structure so that only a small fraction of the plate volume is 

occupied by continuous crystalline calcite (Nissen, 

1969). The spongelike internal structure is ramified 

with mesodermal tissue. Collagen fibers occur in the 

hollow spaces between the trabeculae of the 

echinoderm. It is possible that nucleation started in the 

spaces between the trabeculae as a result of reaction of 

calcite in the skeleton with complex organosilicic acids 

that were produced by the reaction of decomposing organic matter with pore waters heavily enriched in silica 

either from in situ release or from siliceous skeletons. In 

this way silica would be precipitated and replace calcite, 

probably on a molecular basis. However the silica concentration in the intragranular cherts took place, it 

certainly started prior to lithification just below the 

sediment-water interface and, probably, before the 

transition from the original high-Mg calcite skeleton to 

stable low-Mg calcite. 

DOLOMITE IN CHERT 

The presence of dolomite in chert has been recorded 

by many authors (for example, Pittman, 1959; Banks, 

1970; Rapson-McGugan, 1970). Pittman (1959) suggested that this is evidence for postdolomite origin of 

the chert. He suggested that the dolomite was formed 

from the original limestone, the remains ofwhich were 

subsequently replaced by silica. This explanation for 

the dolomite rhombs is not acceptable for the cherts of 

the Lisburne Group. Dolomite is sometimes present in 

chert when it is totally absent from the host limestone. 

Dolomite rhombs are often concentrated along the margins of the intragranular chert; these rhombs suggest 

that occurrence of dolomite in chert is a genetic association. 

In some samples the polomite in chert is euhedral (pl. 

8, figs. 7, 8), while in others the rhombs are strongly 

corroded. The dolomites in the intragranular chert of 

crinoid plates (see above) are commonly rich in iron and 

concentrated along the edges of the chert, whereas in 

the matrix chert no iron enrichment was observed. 

Plate 9, figure 3, shows an example ofthe concentration 

of iron-rich dolomite at the edge of chert developed 

within a crinoid plate. The rhombs and patches of 

rhombs tend to be elongated parallel to the direction of 

cleavage of both the crinoid plate and its syntaxial 

overgrowth. The distribution of the dolomite can be 

related to that of a ((reaction rim" in which the dolomite 

is a product of chert formation. 

If organosilicic acids generated in the pores of both 

crinoid plates and fibrous pelecypods are responsible for 

the development of intragranular chert, as previously 

suggested, then the solution of calcium carbonate on a 

microscopic scale will result in simultaneous deposition 

of chert. The source of magnesium for the dolomite is 

almost certainly the high-Mg calcite of the original 

crinoid skeleton, but such impurities as iron are concen-
SULFATES 31 

trated within the dolomite lattice. In the example illustrated on plate 9, figure 3, the presence of a ureaction 

rim" of iron-rich dolomite suggests that a process of 

progressive solution and reprecipitation of dolomite operates as the chert develops in the crinoid ossicle, but 

this process is by no means ubiquitous as evidenced by 

the homogeneous distribution of dolomite rhombs in 

some intragranular cherts. Organosilicic acids (Siever 

and Scott, 1963) can presumably dissolve calcite into 

solution but leave dolomite largely insoluble at the 

reaction interface. The restriction of dolomite to a reaction rim suggests that a local increase of acidity within 

earlier chert will lead to solution of early dolomite, 

which in turn will be reprecipitated at the chert-calcite 

margin. 

SULFATES 

Three sulfate minerals, anhydrite (CaS04 ), celestite 

(SrS04), and barite (BaS04), occur as rare accessories in 

the Lisburne Group of the subsurface, but none have 

been found in the surface outcrops of the Sadlerochit 

Mountains. This absence from the outcrops may well be 

a function of subaerial solution; nevertheless, no resultant casts have been recorded either in hand specimen 

or in thin section. 

The distinction between these three minerals is often 

difficult in this section, all three crystallizing in the 

orthorhombic system. Anhydrite has the lowest relief 

and highest birefringence; the distinction between barite and celestite requires the use of an X-ray diffractometer or detailed refractive index measurements before positive identification is possible. 

ANHYDRITE 

Description.-Anhydrite occurs in cores from at least 

two wells about 1,500 feet beneath the top of the Lisburne Group. It occurs in two distinct habits, both associated with microdolomite. These are: 

1. Nodules as much as 2 em in diameter· composed 

of felted prisms of anhydrite with a curvilinear 

orientation parallel to the outline of the 

nodule (pl. 11, fig. 4); and 

2. Poikilotopic anhydrite (as much as 1 mm in 

diameter) enclosing abundant microdolomite. 

Interpretation.-The crystal habits of the anhydrite 

are closely comparable with those described and illustrated by Wood and Wolfe (1969) from the Arab-Darb 

Formation of the Arabian Gulf. An arid supratidal 

(sabkha) origin has been suggested for the Arab-Darb 

Formation. Shearman (1966) regarded all nodular 

anhydrites as indicating formation within the capillary 

zone of arid supratidal environments. The poikilotopic 

anhydrite is considered by Wood and Wolfe to be of early 

secondary origin, and that it probably was formed by 

the enlargement of anhydrite cement between dolomite 

rhombs by the progressive replacement of the dolomite. 

Plate II, figures 3 and 5, show two examples that 

suggest anhydrite has been taken into solution even in 

the subsurface. Figure 5 illustrates nodules in a laminated dolomite lined with a 1-mm layer of cryptocrystalline silica and largely filled with sparry calcite. The 

sparry calcite does not completely occupy the nodule. 

The preservation of good crystal terminations on the 

calcite suggests that the nodules were at one time voids 

subsequently infilled by both silica and calcite deposited 

from solution. The nodules probably were initially 

composed of anhydrite (cf. Wood and Wolfe, 1969, pl. 1). 

They evidently formed before the lithification of the 

rock, because the laminae above them are arched. The 

solution of the original anhydrite probably took place in 

interstratal solutions at an early stage of diagenesis. 

Plate II, figure 3, shows a poikilotopic development of 

silica in dolomite whose external form is closely comparable with the poikilotopic anhydrite of Wood and 

Wolfe (see their plate IliA); this form could also 

represent solution of an original anhydrite. 

Armstrong, Mamet, and Dutro (1970) and Armstrong 

(1973) have recorded algal-mat dolomites comparable 

to that illustrated in plate 11, figure 5. These rocks 

occur in the Lisburne Group in the Sunset Pass section 

(68A-4N4B), in the central Sadlerochit Mountains 

(68A-3), and in the Franklin Mountains (68A-1), about 

870 feet, 650 feet, and 800 feet, respectively, beneath 

the top of the sections. An intertidal sabkha origin has 

been inferred for these rocks, and the discovery of 

sabkha-type anhydrites in the subsurface could support 

this conclusion. 

CELESTITE 

Description.-Celestite occurs abundantly in a 4-foot 

interval of core in one of the wells in which anhydrite 

has been observed and below the lowest record of 

anhydrite. Two of its distinct habits appear to be dependent on the nature of the host rock. These are: 

1. Equigranular texture with partly interlocking 

crystals as much as 2 mm long. The celestite 

crystals are free from inclusions except for 

minute laths of anhydrite, the subparallel 

orientation of which ignores the orientation of 

the celestite. The host rock is a microdolomite 

(crystal size <5 JLm) with scattered calcite 

crystals of similar size. Patches of the host 

contain relics after a pellet limestone, but the 

microdolomite between individual crystals of 

celestite parallels the crystal margin as 

though the celestite formed by pushing aside 

the host rock rather than by replacement. The 

anhydrite inclusions are probably a replace-
32 DIAGENESIS AND STRATIGRAPHY OF THE LISBURNE GROUP LIMESTONES, NORTHEASTERN ALASKA 

ment product after celestite-possibly in response to a slight prevailing stress, and 

2. Partly dolomitized oolite pellet grainstone with 

the celestite occupying the intergranular 

spaces with poikilotopic or simple pore-fill 

textures (pl. II, fig. 2). The dolomite (individual crystals are <5~-tm) appears to be scattered through the clasts but is occasionally 

concentrated as fringes to them. The dolomitization certainly took place after the formation 

of the oolite skin but before cementation by 

celestite. In one specimen the oolite pellet 

grainstone has both celestite and calcite cement. Both minerals have a pore-fill texture, 

and from their relationship it is difficult to be 

certain which was deposited first, but an isolated example of a fringe of sparry calcite 

around a grain completely enclosed in celestite suggests that the calcite was the first to 

crystallize. Veinlets crosscut the rock, but 

their mineral filling faithfully reflects the nature of the immediate host. 

lnterpretation.-Many authors have recorded the 

presence of celestite in minor amounts in carbonate· 

rocks (Deer and others, 1966). Evans and Shearman 

(1964) have described anhedral and ((rosette" type 

celestite from modern algal-mat sediments of the 

Trucial Coast of Arabia. Kinsman (1969a) recorded that 

celestite is a fairly common early diagenetic minor 

mineral of coastal sabkhas and is most abundant in 

areas of intense dolomitization. In addition, Schmidt 

(1965) has described both replacement and cement 

celestite in the Gigas Beds of northwest Germany, the 

habits of which are closely comparable to those 

described from the Lisburne Group. 

Recent work by Kinsman and Holland (1969) on the 

coprecipitation of strontium with aragonite has shown 

that the ratio of Sr+2fCa+2 in the aragonite (if other 

factors are equal) decreases with increasing temperature but is independent of the rate of precipitation. 

Kinsman (1969b) has also shown that skeletal aragonite can be distinguished from inorganic aragonite on 

the basis of the lower strontium content. For example, 

the Sr+2 content of coral aragonite in the Arabian Gulf is 

7,740± 300 ppm (parts per million) while that of probable inorganic lagoonal aragonite muds is 9,390± 500 

ppm. 

The metastability of aragonite leads to its conversion 

to low-Mg calcite either by large-scale solution and precipitation that destroy the original texture of the 

aragonite grains or by piecemeal solution and immediate reprecipitation on a submicrometre scale that 

preserves the original texture. Stehli and Hower (1961) 

have shown the median Sr+2 content of Pleistocene calcite limestones of Florida is 1,100 ppm. Although Sr+2 

concentrations show considerable variation in both calcite limestones and dolomites ( < 1,000 ppm Sr dolomites 

of the Trucial Coast sabkhas (Kinsman, 1969a)), the 

differences between these values and those of original 

aragonite are very high. These concentrations then 

provide pore waters with a high Sr+Z/Ca+2 ratio as demonstrated by Harriss and Matthews (1968) in the 

Pleistocene of Barbados. Kinsman (1969a) suggested 

that movement of diagenetic pore waters gives higher 

Sr+ 2 values in the downflow direction. 

From this data we infer that the original aragonite of 

both the open-water and sabkha carbonate rocks may 

have been the source of the Sr+2 , and the excess S04 -z 

ions may have been provided during sabkha sedimentation. The I downward migration of pore fluids would 

then provide a mechanism for their progressive 

enrichment in Sr+2 until a critical value was reached 

to allow formation of celestite. 

BARITE 

Barite has been recorded in only two samples of Lisburne Group rocks from the subsurface. The samples 

were taken within 6 feet of each other but in a well from 

which no sabkha-type sediments or other sulfate minerals have been recorded. The barite occurs in isolated 

clear porphyrotopes as much as 1 mm long in both pellet 

grainstone and an iron-rich wackestone (pl. 11, fig. 1). 

The euhedral shape of the crystals and the absence of 

inclusions suggest that the barite has, like celestite, 

formed by pushing aside the host rock rather than by 

replacement. Barite is often a product of lowtemperature hydrothermal alteration (Dunham, 1934), 

but no evidence of this has been found in the Lisburne 

Group. 

MARBLE 

Recrystallization of sedimentary limestones (marbles) is defined by Spry (1969, p. 114) as ((the reconstitution of an existing phase which may consist merely of an 

increase (grain-growth) or change in grain shape by 

grain boundary movement or by coalescence without 

nucleation." Recrystallized limestone-marble-is 

found in both the western Sadlerochit Mountains 

(69A-1) and Old Man Creek (69A-4/4K) sections interbedded with unaltered sedimentary limestones. 

PURE CALCITE MARBLES 

WESTERN SADLEROCHIT MOUNTAINS SECTION 

In the western Sadlerochit Mountains section 

(69A-1), the marbles are found in the interval 
MARBLE 

1,080--1,140 feet (pl. 2, fig. 2; pl. 6, figs. 7, 8) in a discrete 

33 

unit and at 1,015 and 998 feet as thin individual layers 

interbedded with unaltered fine-grained bioclastic pellet packstones. These marbles are composed exclusively 

of calcite. The individual anhedral grains show no sign 

of their origin, and the extensive interfingering of the 

grain margins has obliterated any intergranular space. 

The fabric can be referred to as ~~granoblasticpolygonal" (Spry, 1969, p. 187) and could be the product 

of posttectonic (annealing) crystallization (Turner and 

Weiss, 1963, p. 354-355). 

Three main fabric types are traceable in the 69A-1 

marble zone. These are, in probable order of formation: 

1. Coarse grains of calcite with well-developed 

twinning that usually have corroded margins 

and often occupy the core of even larger unstrained calcite grains. The twinned grains 

are probably remnants of crinoid ossicles, as 

shown by the occasional preservation of the 

characteristic pore pattern upon which the 

twinning has been superimposed. 

2. Clear untwinned equidimensional calcite that 

replaces the earlier twinned calcite. Extensive interpenetration of grain margins and 

lobate triple-point grain boundaries are common (Spry, 1969, p. 19); the grains intersect at 

approximately 120°. 

3. Minute ( ~ 10p,m) equidimensional calcite 

grains are distributed across both earlier fabrics but preferentially developed along grain 

margins. 

Figure 21 shows the position of the various rock types 

within the interval 950--1,150 feet, section 69A-1, and 

the proportions of the various recrystallized fabric types 

are listed against the level of each marble sample. Over 

the section 1,080--1,140 feet, which is exclusively marble, the proportion of the latest granulation fabric type 

increases progressively toward + 1,140 feet. The 

sedimentary limestones on either side of this zone show 

no effect of recrystallization. 

OLD MAN CREEK SECTION 

In the Old Man Creek (69A-4/4K) section (pl. 6, figs. 

3-5), the modification of the original sedimentary 

limestone texture is not only more varied in its effect 

but also more extensive in its development. The total 

1,500 feet of section exhibits some degree of fabric 

modification in the limestones, but the interbedded 

dolomites, apart from partial dedolomitization, appear 

unaffected. Not only are the three fabric types described 

-from the western Sadlerochit Mountains section 

(69A-1) extensively represented but two additional 

types were noted. These are: 

FEET ABOVE 

BASE OF 

LISBURNE 

GROUP 

1150 

1100 

1050 Crinoid 

packstone 

r Bryozoan- crinoid grainstone 

Sole of thrust fault? 

Intensity of metamorphic 

recrystallization progressively 

decreases to 1, 080 It 

- Bryozoan/ 

Y////h~--------~------~ cnnoid 

. .. r?J.!9;; 

Bryozoan/ 

crinoid 

packstone 

950__j__ _ _J 

~ Zone of marble 

Minor thrust 

adjustments 

FABRIC TYPE 

(Asinfig,24l 

10 Trace 90 

10 10 80 

50 40 10 

40 50 10 

70 30 

10 90 

70 30 

50 40 10 

FIGURE 21.-Stratigraphic distribution of metamorphic fabrics in 

dynamically recrystallized limestones, western Sadlerochit Mountains section 69A-L The columns at right show percentages of each 

of three fabric types developed in samples from various horizons in 

the Lisburne Group. See text for description of the fabric types. 

1. Strongly lineated rocks in which probable 

crinoid ossicles have been deformed into ellipses with an elongation ratio (a:b) of up to 

4:1. Recrystallization is lacking; the intergranular material of packstones remains as 

carbonate mud. Thin discontinuous en echelon veinlets filled with sparry calcite are 

commonly superimposed upon this lineated 

fabric and intersect the lineation at up to 20°. 

2. The twinning of originally untwinned crinoid 

ossicles and interpenetration of the margins 

with the intergranular sparry calcite cement. 

MODE OF ORIGIN 

The stratigraphic restriction of the marbles in the 

western Sadlerochit Mountains section (69A-1) and the 

large distance from the nearest known igneous mass 

(Mount Michelson is about 20 miles distant) makes 

1 metamorphism along a major bedding-plane thrust the 
34 DIAGENESIS AND STRATIGRAPHY OF THE LISBURNE GROUP LIMESTONES, NORTHEASTERN ALASKA 

RELEASE 

OF RESIDUAL 

STRAIN ENERGY 

MAXIMUM 

SHEAR 

DEFORMATION 

ORIGINAL 

SEDIMENTARY 

FABRIC 

TENSION CRACKS AT ANGLE TO 

SHEAR ORIENTATION. PRESERVATION OF SHEAR FABRIC 

\ 

GRANULATION CONCENTRATED 

ALONG GRAIN MARGINS 

POSTKINEMATIC ANNEALING 

(OBLITERATION OF EARLIER 

SHEAR FABRIC) 

TWINNING OF CRINOID OSSICLES 

AND GRAIN INTERPENETRATION 

CRINOID PACKSTONE/GRAINSTONE 

FIGURE 22.-Generalized sequence of dynamic metamorphism in 

limestones of the Lisburne Group. 

obvious mechanism to produce such extensive fabric 

alteration. No thrust was originally noted in the field, 

but in support of the thrusting hypothesis there is a 

marble unit (1,190 ft) that coincides with a marked 

break in the section (see figs. 2, 5) and this break has 

been suggested to be the contact between the Alapah 

and Wahoo Limestones. A study of the literature indicates that extensive production of marble along a thrust 

plane is not common, but Dr. Janet Watson of Imperial 

College, University of London, has suggested to us that 

a similar (but thinner) development occurs at the base 

of the Glaurus thrust in the Helvetic Alps of eastern 

Switzer land. 

In spite of the differences between the fabric types in 

the recrystallized limestone of the western Sadlerochit 

Mountains (69A-1) and Old Man Creek (69A-4/4K) sections, it is possible to incorporate the differing fabrics 

into a single mechanism of origin (figs. 22-24). The first 

stage is the development of twinning in the coarsegrained element of the original sedimentary fabric, that 

is, the originally untwinned crinoid debris. The atomic 

rearrangement necessary in single calcite crystals for 

polysynthetic twinning is simple and can easily be inEn echelon 

tension cracks 

at an angle to 

the deformation 

Parallel deformation 

or original 

sedimentary fabric 

Twinning 

of crinoid 

plates 

Bryozoan 

fragments 

Crinoid 

ossicles 

Carbonate 

mud 

Granulation 

concentrated 

along major 

grain margins 

Annealed 

calcite 

Triple-point 

junction 

Twinned' 

relicts 

FIGURE 23.-Diagrammatic sequence of dynamic metamorphism in 

limestones of the Lisburne Group. 

duced artifically either by pressing a crystal with a 

knife in the appropriate direction (Spry, 1969, p. 85) or 

even during the preparation of a thin section (Dr. Janet 

Watson, oral commun., 1970). Griggs, Turner, and 

Heard (1960) produced twinning in single crystals of 

calcite by deformation. It is probable that twinning was 

superimposed on the coarser calcite crystals (either 

large crystals of sparry calcite cement or crinoid ossicles) at the first stage of deformation, and the results 

have only been preserved where the annealing recrystallization has not totally obliterated the early-stage 

fabric. 

When the stress induced by thrust movement passes 

the appropriate plastic field to reach the fracture point 

for calcite, shearing produces parallel deformation of 

the original fabric and stretches the large grains. Upon 

reaching the fracture point, the free energy resulting 

from strain within the lattice is released by fracturing. 

The residual-strain energy is then gradually released 

and produces a significant temperature rise. 
MARBLE 35 

Coarse crystalline calcite with 

well-developed twin plane 

Clear unstrained equidimensional 

calcite replacing the earlier 

well-twinned calcite; extensive interpenetration of grain 

margins. Postkinematic in 

origin 

Development of minute equidimensional calcite grains that 

are preferentially developed 

along grain margins although 

distributed across both earlier fabrics 

FIGURE 24.-Sequence of crystallization in marble of section 69A-L 

This residual-strain energy provides the mechanism 

for the strain-free annealing recrystallization, which 

results in the large untwinned crystals (often including 

relicts of twinned calcite) with approximately 120° 

triple-point junctions. The grain size of an annealed 

fabric increases with time and with rise in temperature 

(Turner and Weiss, 1963, p. 332). Griggs, Turner, and 

Heard (1960) have shown that for annealing in a low 

strain-stress field, recrystallization of Yule Marble was 

only partly complete at 800°C. This temperature, however, is not likely to be produced along a thrust plane. 

Buerger and Washken (1947) commented that a mineral will not recrystallize without solvents unless 

heated to a critical temperature. It would appear that to 

obtain the annealed fabrics observed in the Lisburne 

Group, extensive fluids must have been present after 

the thrusting episode. These fluids were probably acidic 

and occurred along the intergranular boundaries, 

which would allow piecemeal change of the fabric. Lack 

of annealing in the rarely preserved shear fabrics and 

associated on echelon tension gashes (especially in the 

Old Man Creek section) can be explained by the absence 

of postshearing fluids. 

The final stage of recrystallization is represented by 

granulation of the annealed fabric mainly along grain 

margins but also within the grains themselves. This 

granulation is possibly a result of rotation of individual 

crystals. If this dynamic metamorphic sequence is 

realistic, then it appears that the metamorphism along 

the suggested thrust in 69A-1 is restricted to the sole 

and is absent from the thrust sheet itself. 

The fabric changes in the Old Man Creek section 

(69A-4! 4K) are much more extensive than those in the 

western Sadlerochit Mountains section (69A-1). The 

age of the Mount Michelson pluton is not certain 

(Leffingwell, 1919; Sable, 1965; Reiser, 1970). Although 

no fabric is definitely attributable to thermal alteration, it is possible that repeated shearing directly related to earth movements immediately prior to and 

associated with emplacement of the granite was the 

major mechanism of metamorphism. The extensive 

interfingering of grain margins in the rocks of the Old 

Man Creek section could be a reflection of thermal alteration. The preservation of shear fabrics in the Old 

Man Creek section suggests that interstitial fluids were 

localized, in contrast to the marbles of the western Sadlerochit Mountains section. This evidence would support a post-Pennsylvanian age for the Mount Michelson 

pluton. 

DOLOMITES ASSOCIATED WITH MARBLE 

Description.-An apparent anomaly in the Old Man 

Creek section is the absence of obvious stress response 

in the dolomite layers abundantly interbedded with the 

altered limestones. Two explanations are possible for 

this phenomenon-either (1) the time of dolomite formation was later than the shearing and subsequent 

annealing of the limestone, or (2) dolomite responds 

differently to shearing stress in that it can remain unaffected while calcite reaches its fracture point and becomes subsequently annealed (fig. 25). 

The distribution of dolomite appears to be directly 

related to the original sedimentary fabric, and rhombs 

superimposed on a sheared or completely annealed 

limestone fabric have not been observed. Where dolo-

. mite is associated with marginally annealed limestones, the rhombs tend to be at least partly dedolomitized; they show corroded edges and internal 

spotty replacement by calcite. These facts suggest that 

the dolomite was formed before shearing occurred. 

Mode of origin.-If, as suggested in the previous section, calcite and dolomite behave differently under 
36 DIAGENESIS AND STRATIGRAPHY OF THE LISBURNE GROUP LIMESTONES, NORTHEASTERN ALASKA 

(I) 

(I) 

w 

a: 

~ 

(I) 

Elastic field Nonelastic field 

-1- oo~\o~m~it~e ___ _ 

STRAIN 

FIGURE 25.-Possible stress-strain relation of calcite and dolomite. 

Note that at a certain stress (x), calcite will fracture, whereas 

dolomite will still be in the elastic field. 

shearing stress, a more detailed discussion of the relevant stress-strain curves is necessary. 

Stress fields are expressed in terms of three vectors 

mutually at right angles and termed <Tl, <r2, and <Ta in 

decreasing order of magnitude (Mogi, 1971 ). In thrust 

faults the dominant direction of movement is horizontal 

with <Tl and <T2 in the horizontal plane and <Ta vertical 

where <Tl > <T2 > <Ta. The elastic and plastic fields of 

deformation can be delimited on a stress-strain curve 

for a given mineral under constant temperature conditions. Mogi (1971) has shown that the stress-strain 

curves for calcite and dolomite diverge in a heterogeneous stress field, as they do in thrust faulting, with dolomite having a higher fracture point and greater ductility than calcite. Figure 25 indicates a possible stressstrain relation between calcite and dolomite which in 

thrust faulting would allow calcite to fracture while 

dolomite was still in the elastic field, as evidenced by the 

absence of flow or preferred orientation in the dolomite. 

This relationship cr>uld explain the apparent anomaly 

oflimestones that exhibit strong deformation or annealing fabrics (interbedded) with apparently unaltered, 

but prekinematic, dolomites. 

RELATIVE AGES OF FORMATION OF 

DIAGENETIC FEATURES 

The preceding sections have presented the evidence 

and discussion for postdepositional alteration of the 

mineralogy and fabric in the Lisburne Group of the 

Sadlerochit Mountains. This section places these 

diagenetic phenomena into a time sequence and describes late-stage features formed as a result of overburden pressure or tectonic activity (the occurrence of 

marble having already been discussed). No attempt is 

made to reiterate the discussions of previous sections, 

and the conclusions are presented without further 

justification. It is often possible to assess the relative 

order of the start of development of the various diagenetic features, but comments on the relative time span or 

continuity of any process are usually conjectural. 

1. The original nucleation of intragranular chert 

within crinoid plates and pelecypod fragments is 

considered to be the earliest phase of diagenetic 

alteration. Nucleation probably started immediately upon deposition prior to the conversion 

of original high-Mg crinoid debris or aragonitic 

pelecypod shells to stable low-Mg calcite. In the 

crinoids, dolomite formed as part of this 

silicification process from magnesium liberated 

from high-Mg calcite. This change was probably 

coincident with the development of micrite envelopes from marginal algal borings immediately 

upon death of the organism. Once nucleated, the 

chert developed gradually until at least after the 

second phase of calcite cementation has been completed. 

In contrast, the development of ~~matrix" chert is 

considered to be of direct biogenic origin, and its 

present-day fabric is related to its progressive recrystallization with time, generally producing a 

homogeneous texture that obliterates the original 

skeletons. 

2. Closely following the nucleation of intragranular 

chert was the development of first-phase sparry 

calcite cement either as syntaxial overgrowths on 

the crinoid plates or as a fringe of fibrous crystals 

on carbonate clasts, such as oolites or pelecypods. 

The syntaxial overgrowths developed preferentially in the direction of the c axis (or axes) of the 

crinoid plates; these overgrowths acted as single 

crystals, by physically pushing aside rather than 

replacing any other carbonate debris. This 

first-phase cement in the Lisburne Group is 

everywhere poor in iron. 

High-Mg calcite debris probably lost its Mg2+ at 

this time, almost invariably on a piecemeal basis 

allowing the original fabric to be retained in 

low-Mg calcite. 

The change from aragonite to low-Mg calcite was 

generally later than the transformation of highMg calcite. Sometimes this change resulted from 

complete solution of aragonitic clasts. The micrite 

envelope and the first-phase sparry calcite fringe 
RELATIVE AGES OF FORMATION OF DIAGENETIC FEATURES 37 

provided a strong and probably elastic coating to 

the resulting void, which explains the scarcity of 

collapsed envelopes. The void was subsequently 

filled with equant sparry calcite, probably of the 

second phase, which obliterated the original internal fabric. When the test or skeleton was intimately intermixed with organic layers (as in 

fibrous pelecypods and oolites), the replacement 

took place as a result of small-scale solution of 

aragonite and almost simultaneous redeposition 

oflow-Mg calcite. This process allowed the preservation of the original aragonitic fabric after transformation to calcite. 

3. First-phase dolomite, the next new mineralogical 

form, developed into two distinct types. The first 

type was fine-grained dolomite that formed either 

as an early phase of sabkha (supratidal/intertidal) 

sedimentation from original carbonate mud or 

from the alteration of lagoonal carbonate muds. 

The fact that most of the dolomite is rich in iron 

may suggest that the Mg-rich waters that induced 

the alteration were derived from a reducing environment. Many of these dolomites were subjected 

to aggrading neomorphism that produced a fabric 

an order of magnitude coarser than when they 

were originally formed. Associated with the 

sabkha dolomites was the formation of anhydrite 

nodules and celestite. Some of these nodules have 

been replaced by calcite, probably during or after 

the development of second-phase sparry calcite 

cement. 

The second type of first-phase dolomite occurs as 

coarse rhombs, many larger than 200 micrometres, that developed in the grainstone facies 

and only partly replaced the clasts. These rhombs 

tend to be zoned as a result of variation in iron 

content; the zoning in turn reflects their piecemeal 

formation. The incorporation of iron into the 

dolomite lattice produced a nonstoichiometric 

mineral that appears to have been unstable and 

particularly prone to dedolomitization. Iron was 

commonly forced out of the dolomite lattice to form 

a rim around the rhomb now preserved as Fe2 03.' 

These large rhombs often occur in intergranular 

clusters that are commonly crosscut by secondphase sparry calcite cement. 

4. The fourth stage of diagenesis (coinciding with Stage 

IV of Land, 1967) was the formation of secondphase sparry calcite cement, which obliterated 

any pore space available in the limestones of the 

Lisburne Group. The cement occupies the intergranular space and fills the casts produced by solution of originally aragonitic bioclasts. The crystals 

tend to be subequant and become coarser toward 

the center of the void-fill. The presence of enfacial 

junctions between the first- and second-phase 

sparry calcite cements suggests a distinct time 

lapse between their formation. The second-phase 

sparry calcite, in contrast to the first phase, is 

often rich in iron; the addition of iron implies that 

fluids from which the cement was derived came 

from a ~~distant source." 

5. The second phase of dolomite formation followed the 

introduction of the void-filling sparry calcite cement. Some of the macrodolomite in the Lisburne 

Group may have been developed during this phase 

of diagenesis, but the only positive evidence for its 

existence are the iron-free fringes of dolomite 

around the iron-oxide-rimmed first-phase dolomite and as an overgrowth that postdates the dedolomitization. 

Probably this phase is quantitatively of minor importance, but on its termination the rocks (except 

the marble) acquired the general fabric and 

mineralogy that have persisted until the present 

day. At this stage it is worth emphasizing that in 

the rocks in which intragranular chert has developed, the final rock type is a function of the 

nature of both the grains and the intragranular 

material (fig. 20). It must be emphasized, however, 

that the processes of alteration do not always go to 

completion. 

In grainstones, as chert developed in the crinoids, 

sparry calcite filled the intergranular space. As 

chert developed around the original nucleii, the 

other debris, the Bryozoa (mainly) and the sparry 

calcite cement, were eventually replaced, and the 

diagenetic end product is banded chert. 

In packstones and wackestones in which the intergranular spaces were originally filled with carbonate mud, chert developed in the crinoid debris, 

but the carbonate mud was preferentially 

dolomitized. The chert tended to be restricted to 

the crinoids, but dolomite replaced all the carbonate mud and the bryozoan debris as well. The 

diagenetic end product is an admixture of chert 

and dolomite. 

In mudstones where recognizable fossil debris is 

less than 10 percent, the carbonate mud was replaced by dolomite with no accessory minerals. 

6. The first late-stage diagenetic features were stylolites, interfingering planes that almost certainly 

formed by solution as a response to overburden 

pressure. The minimum amount of solution that 

took place along any stylolite can be estimated 

from the amplitude of interfingering. Dunnington 

(1967) suggested that stylolites develop under at 

least 2,500 feet of overburden in the Dukhan Field 
38 DIAGENESIS AND STRATIGRAPHY OF THE LISBURNE GROUP LIMESTONES, NORTHEASTERN ALASKA 

of Qatar. Stylolites are rare in thin sections of 

Lisburne Group rocks examined for this study, but 

it must be remembered that only a very small 

proportion of the total section was sam pled, even 

though samples were taken at 5- to 10-foot intervals. The locus of stylolite development probably 

was preferentially determined by thin clay horizons. Plate 12, figure 2, illustrates a Lisburne 

Group stylolite with an amplitude of 0.5--1.5 mm 

whose plane is filled with bitumen and clay containing dolomite rhombs. Dolomite is absent from 

the adjacent host rock, so the rhombs in the stylolite probably were produced by very late stage 

Mg-rich solutions passing along the plane of the 

stylolite. 

7. The final stages of diagenesis were associated with 

tectonic activity. Marble developed along the sole 

of bedding-plane thrusts, and intensive fractures, 

many filled with late-sparry calcite, transected all 

other features of the Lisburne Group (pl. 6, figs. 

3-7). 

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Page 

A 

Abu Dhabi ---------------------------------- 22, 23 

lagoons ------------------------------------ 22 

sabkhas ------------------------------------ 23 

Acknowledgments -------------------------------- 2 

Alapah Limestone ________________ 1, 2, 7, 10, 11, 15 

age---------------------------------- 10, 12, 13 

basal units ------------------------------ 10, 13 

carbonate mud ------------------------------ 22 

depositional environments ____________ 10, 11, 23 

dolomite -------------------------------- 23, 24 

eastern Sadlerochit Mountains section __ 12, 13, 23 

grainstones_____ _____ ___ ________ ___ _____ _____ 21 

Lisburne Group ________________ 1, 2, 7, 10, 11, 15 

microdolomite ------------------------------ 23 

Old Man Creek section __________________ 13, 23 

pellets -------------------------------------- 20 

Plunge Creek section __________________ 13, 22, 23 

type locality---------------------------------- 1 

upper unit ------------------------ 7, 11, 15, 23 

Alapah Limestone-Kayak(?) Shale boundary ______ 10 

Alapah Limestone-Wahoo Limestone 

boundary ________________________ 11, 34 

Alaska, northeastern, lithofacies maps ________ 14, 15 

AI Bahrani delta, Abu Dhabi ____________________ 20 

Alga, chlorophyte -------------------------------- 20 

Algae --------------------------------------- 19, 29 

dominant amino acids ________________________ 20 

Algal borings ____________________________ 18, 19, 36 

Algal mats ________________________ 10, 15, 21, 23, 24 

Algal-mat dolomites ____________________________ 31 

Algal-mat laminations __________________________ 10 

Algal-mat sediments __________________________ 8, 32 

Alizarin-RedS stain ____________________________ 25 

Alluvium, Pleistocene _________________ _____ ______ 1 

Amino acids ------------------------------------ 20 

Anaktuvuk River valley __________________________ 1 

Anhydrite _______ ------------------------------- 31 

description __________________________________ 31 

inclusions ________________________________ 31, 32 

interpretation ------------------------------ 31 

microdolomite ______________________________ 31 

nodules ____________________________________ 31 

nodules, formation ______________________ 31, 37 

poikilotopic __________________________________ 31 

sabkha-type _______________________________ 31 

Ankerite---------------------------------------- 26 

Arab-Darb Formation, Arabian Gulf _______________ 31 

Arabian Gulf ____________________________ 21, 23, 32 

Arabian Gulf sabkhas ________________________ 23, 31 

Aragonite __________________ 9, 16, 18, 22, 28, 32, 36 

coprecipitation ______________________________ 32 

coral________________________________________ 32 

inorganic____________________________________ 32 

low-Mg calcite ------------------------------ 19 

metastability-------------------------------- 32 

mud---------------------------------------- 32 

oolitic, biochemical origin ________________ 20, 27 

precipitation -------------------------------- 32 

reprecipitation ------------------------------ 32 

skeletal ------------------------------------ 32 

solution ____________________ 18, 19, 20, 21, 32, 37 

strontium content_ ___________________________ 32 

Aragonitic clasts ______________________ 18, 21, 36, 37 

Argillites -------------------------------------- 15 

Armstrong, Augustus, cited ________________________ 2 

Aston, E., cited __________________________________ 2 

Atlantic, North---------------------------------- 30 

Atlantic, South---------------------------------- 30 

INDEX 

[Italic page numbers indicate major references] 

Page 

Atlantic Richfield/Humble Prudhoe Bay 

State Well No. 1 ____________________ 15 

B 

Bahama Banks ------------------------------ 19, 22 

Barbados________________________________________ 32 

Barite -------------------------------------- 31,32 

porphyrotope -------------------------------- 32 

Barrow No. 3 well ------------------------------ 15 

Belmont Formation, Jamaica ____________________ 21 

Bermuda Rise ---------------------------------- 30 

Bibliography, selected ____________________________ 38 

Bioclastic debris ______________________ 6, 9, 18, 23, 26 

Bioclasts ---------------------------------------- 29 

aragonitic ------------------------ 18, 21, 36, 37 

pelecypod ---------------------------------- 19 

Biostratigraphic correlation ______________________ 12 

Birdseye structures------------------------------ 15 

Bitumen---------------------------------------- 38 Bonaire, Netherlands Antilles ____________________ 23 

Brachiopod fauna-------------------------------- 14 

Brooks Range, eastern, Paleozoic sequence __________ 2 

northeastern------------------------------ 1, 12 

Lisburne Group, outcrops ___________________ 1 

outcrops______________________________________ 1 

Bryozoa __________________________ 6, 8, 17, 18, 28, 37 

grain size ---------------------------------- 22 zooecia_ __ __ _ __ _____ ____ ____ _____ _______ ___ __ 18 

Bryozoan debris ______________ 4, 6, 7, 9, 18, 23, 26, 37 

Bryozoan fronds _____________________________ 18, 29 

c 

Calcite __________________ 6, 7, 8, 10, 16, 22, 24, 25, 33 

annealed __________________________ 10, 22, 33, 35 

cement______________________________________ 32 

cryptocrystalline ____________________________ 19 

crystallization ________________________ 32, 33, 34 

crystals _____________________ 22, 26, 27, 30, 31, 34 

deformation _____________________________ 34 

sparry __________________________ 20, 29, 31 

twinning ________________________________ 34 

dedolomitized_ __ ___ _______ _____ _____ __ ___ ___ _ 25 

drusy ------------------------------------- 21, 27 Fe2+ ___ ____________________________ _ 18, 21, 26 

fracture point ____________________ 10, 34, 35, 36 

grains, equidimensional ______________________ 33 

equidimensional, minute ________________ 33 

twinned ________________________________ 33 

high-Mg ________________ 16, 17, 18, 22, 27, 30,36 

intrazooecial -------------------------------- 18 

low-Mg __________ 16, 17, 18, 21, 22, 27, 30, 32, 36 

redeposition ____________________________ 37 

metamorphic recrystallization ____ 7, 10, 26, 33, 35 

replacement ______________________ 25, 28, 30, 37 

shearing stress __________________________ 35, 36 

sparry ______________ 4, 10, 18, 21, 24, 25, 26, 29, 

30, 31, 32, 33, 37, 38 

syntaxial over-growth ______ 18, 26, 27, 29, 36 

sponge spicules------------------------------ 30 

stress-strain curves __________________________ 36 

trace cations -------------------------------- 26 

Calcite cement, sparry ____________ 6, 8, 9, 11, 16, 18, 

19,21, 25, 37 

Calcite fabric____________________________________ 16 

Calcium carbonate -------------------------- 22, 30 

deposition ---------------------------------- 22 

lattice types -------------------------------- 22 

neomorphic processes ________________________ 22 

Page 

Calcium carbonate-Continued 

organic matrix ------------------------------ 20 

origin -------------------------------------- 22 

precipitation, inorganic ________________ 21, 22, 27 

recrystallization ---------------------------- 22 

replacement -------------------------------- 29 

source -------------------------------------- 21 

Calcium ions------------------------------------ 27 

Calcium sulfate solutions ------------------------ 25 

Calvert hypothesis ------------------------------ 30 

Canning sag -------------------------------- 14, 15 

Carbla Oolite ____________________________________ 18 

Carbonate, ions __________________________________ 27 

iron-calcium -------------------------------- 26 

lattice ---------------------------------- 26, 27 

Carbonate clasts, fibrous crystals ________________ 36 

Carbonate mud, Alapah Limestone ________________ 22 

aragonitic ---------------------------------- 22 

calcitic______________________________________ 22 

dolomitic -------------------------------- 7, 37 

iron-rich-------------------------------- 24 

intergranular -------------------- 18, 22, 33, 37 

lagoonal, alteration ---------------------- 10, 37 

oolite -------------------------------------- 19 

origin -------------------------------------- 22 original ______________________________ 28, 29, 37 

porosity ------------------------------------ 22 

recent -------------------------------------- 22 

porosity -------------------------------- 22 

replacement -------------------------------- 28 

Carbonate rock classification __________________ 3, 16 

Carbonate rocks, age ________________________ 14, 15 

Atokan ------------------------------------ 14 

Brooks Range, central ____________________ 2, 14 

eastern -------------------------------- 14 northeastern ____________________________ 1 

carboniferous, Sadlerochit Mountains, 

regional relations ____________________ 14 

celestite ------------------------------------ 32 

Chesterian age ------------------------------ 15 

correlation chart, regionaL ___________________ 14 

cross section -------------------------------- 15 

Devonian age ________________________________ 14 

diagenesis ---------------------------------- 16 

Dunham classification ____________________ 3, 16 

Endicott Mountains, petrographic studies ______ 2 

grain-contact fabric __________________________ 20 

iron distribution, environmental significance __ 27 

Lisburne Group __________________ 14, 16, 27, 37 

lithified ------------------------------------ 20 

Naval Petroleum Reserve No. 4 ______________ 15 

open water---------------------------------- 32 outcrop patterns ____________________________ 14 

petrographic studies -------------------------- 2 

sabkha______________________________________ 32 

Sadlerochit Mountains ____________________ 1, 14 

stylolites -------------------------------- 24, 37 

subsurface ---------------------------------- 15 

Carbonate sedimentation ________________________ 27 

Carboniferous carbonate rocks, regional relations __ 14 

Carboniferous marine transgression, 

cross sections ____________________ 14, 15 

Cathodoluminescence---------------------------- 26 

Celestite ---------------------------------------- 31 

anhedral ____________________________________ 32 

cement______________________________________ 32 

crystals ------------------------------------ 31 

description---------------------------------- 31 

formation ---------------------------------- 37 

intergranular __ ___ ____ ___ ___ __ ____ _ ___ __ ___ __ 32 

43 
44 

Page 

Celestite-Continued 

interpretation ------------------------------ 32 

microdolomite ------------------------------ 31 poikilotopic_ ____ ________ __ __________ ______ ___ 32 

pore-fill texture ______________________________ 32 

replacement -------------------------------- 32 

rosette-------------------------------------- 32 

Cement -------------~-------------------------- 20 

celestite ------------------------------------ 32 

sparry calcite ______ 6, 8, 9, 16, 18, 19, 21, 22, 24, 

25, 29, 33, 34, 37 

first stage_________ 17, 20, 21, 24, 26, 27, 36 

iron-poor ________ 18, 20, 26, 27, 29, 36, 37 

pore-fill texture __________________________ 32 

second stage __________ 20, 21, 27, 28, 29, 37 

iron-rich-------------- 9, 20, 21, 26, 27, 37 

origin -------------------------------- 21 

stages -------------------------------------- 27 

vadose zone -------------------------------- 21 

Cenomanian limestone, Lurestan, Iran ____________ 30 

Central Sadlerochit Mountains section, dolomite __ 31 

Chalk ------------------------------------------ 22 

Northern Ireland ---------------------------- 22 

permeability -------------------------------- 22 

porosity ------------------------------------ 22 

Chert -------------------- 8, 9, 17, 23, 24, 27, 28, 30 

banded______________________________________ 37 

biogenic origin---------------------------- 4, 29 

dolomite in ------------------------------ 24,30 

Eocene______________________________________ 30 

Atlantic -------------------------------- 30 

fabric -------------------------------------- 28 

intragranular ______ 6, 8, 17, 18, 28, 29, 30, 31, 37 

nucleation __________________ 6, 17, 29, 30, 36 

Lisburne Group ________________ 2, 28, 29, 30, 37 

macrodolomite ____________ -------------------- 4 

matrix------------------------ 4, 6, 8, 28, 30, 36 

origin ------------------------------ 29, 36 

microdolomite ------------------------------ 4, 6 

origin, mode ---------------------------- 29, 30 

time------------------------------------ 29 Paleozoic____________________________________ 30 

recrystallization ---------------------------- 36 

source of silica ------------------------------ 29 Clay horizons ____________________________________ 38 

Coal seams-------------------------------------- 15 

Coccolith debris -------------------------------- 22 

Colville River ---------------------'------------- 15 

Coorong Lagoon, South Australia ________________ 23 

Corals, Atokan age ------------------------------ 12 

Chesterian age------------------------------ 12 

Lisburne Group-------------------------- 12, 18 

lithostrotionoid ------------------------------ 12 Meramecian age ____________________________ 12 

Osagean age -------------------------------- 12 

rugose -------------------------------------- 12 

solitary ------------------------------------ 18 

stratigraphic range-------------------------- 12 Wahoo Limestone ________________________ 2, 12 

Correlation, biostratigraphic______________________ 12 

dedolomitization zones ____________________ 26, 27 

Lisburne Group ______________________________ 12 

sections __________________________________ 10, 12 

standard American type sections ______________ 12 

standard Eurasian type sections ______________ 12 

Crinoid debris ________ 3, 4, 6, 9, 10, 17, 23, 28, 34, 36 

Crinoid ossicles ------------------------------ 31, 33 

twinned -------------------------------- 33, 34 

Crinoid plates __________________ 6, 8, 9, 19, 23, 30, 36 

crystal size---------------------------------- 22 intragranular chert ________________________ 6, 8 

syntaxial overgrowths ________________________ 36 

Crinoid skeleton -------------------------------- 30 

Crinoids ---------------------------- 6, 8, 17, 28, 36 

chert________________________________________ 37 

Cristobalite ------------------------------------ 30 

Cross sections, Carboniferous marine 

transgression ____________________ 14, 15 

Crystal habits, anhydrite ________________________ 31 

barite -------------------------------------- 32 celestite ________________________________ 31, 32 

INDEX 

Page 

Crystals, micrite -------------------------------- 22 

sparry calcite ------------------------ 20, 29, 31 

first phase-------------------- 20, 26, 27, 29 second phase ______________ 21, 24, 26, 27, 37 

D 

Dedolomite-------------------------------- 4, 10,25 

types -------------------------------------- 25 Dedolomitization ____________ 10, 11, 21, 22, 25, 27, 37 

ancient ------------------------------------ 26 

causes -------------------------------- 6, 24,25 

unconformity surface ________________________ 26 

zones------------------------------------ 26, 27 

Deformation, elastic field ------------------------ 36 

plastic field------------------------------ 34, 36 

Deep Sea Drilling Project ------------------------ 30 De Long Mountains ______________________________ 15 

thrust sheets-------------------------------- 15 

Diagenesis ________________ 6, 7, 10, 15, 29, 36, 37, 38 

Diagenetic features, formation, 

relative ages ------------------------ 36 

Diagenetic history-------------------------------- 2 

Diagenetic processes------------------------------ 1 

Diatomite -------------------------------------- 30 

Diatoms ---------------------------------------- 29 

Dolomite ------------------------------ 4, 10, 22, 25 

aggrading process ____________________________ 22 

algal mat ---------------------------------- 31 

Arabian Gulf sabkhas ________________________ 23 

bitumen -------------------------------- 24, 38 

calcian ---------------------------------- 24, 26 

calcian-ferroan ------------------------------ 23 

composition -------------------------------- 28 

crystals ------------------------------ 8, 24, 32 

zoning---------------------------------- 24 

dedolomitization ---------------------------- 33 

detrital ------------------------------------ 24 

diagenetic ------------------------------ 23,24 

distribution -------------------------------- 35 

epigenetic ---------------------------------- 24 fabric ____________________________________ 22, 23 

Fe2 ____________________________ 4, 23, 24, 25,27 

fine-grained -------------------------------- 37 

first stage __________________________ 4, 27, 28, 37 

iron-rich ____________ 4, 24, 27, 28, 30, 31, 37 

formation ________________________________ 35, 37 

fracture point ________________________ 10, 35, 36 

hematite zones __________________________ 23, 25 

in chert ------------------------------------ 30 

intergranular -------------------------------- 6 

laminated, anhydrite nodules ________________ 31 

lattice ____________________________ 23, 26, 31, 37 

magnesium, source __________________________ 30 

Mahmal Formation, IsraeL ___________________ 26 

Old Man Creek section ____________________ 3, 23 

origin ---------------------------------- 23, 28 

Plunge Creek section ____________________ 3, 4, 23 

primary ------------------------------------ 24 

recent -------------------------------------- 23 recrystallization ____________________________ 23 

replacement -------------------------------- 31 

reprecipitation ------------------------------ 31 

rhombs ____________________ 6, 7, 9, 19, 23, 24, 25, 

27, 30, 31, 37 

distJ;ijn,ltion -------------------------- 31, 35 

iron-poor ---------------------------- 25, 27 

iron-rich __________________ 6, 7, 9, 23, 24, 27 

zoned ________________________ 24, 27, 28, 37 

sabkha ______________________________ 23, 31, 37 

second stage __________________________ 4, 27, 37 

iron-poor __________________ 4, 24, 25, 27, 28 

shearing stress __________________________ 35, 36 

silica, poikilotopic -------------------------- 31 

silicification process __________________________ 36 

sponge spicules------------------------------ 30 stress-strain curves __________________________ 36 

strontium content_ ___________________________ 32 

subdivision__________________________________ 23 

syngenetic ____________________________ 22, 23,24 

Dolomite-Continued Page 

third stage---------------------------------- 27 

trace cations -------------------------------- 26 

western Sadlerochit Mountains section ________ 23 

Dolomites, associated with marble ________________ 35 

associated with marble, description __________ 35 

mode of origin -------------------------- 35 

Lisburne Group ____________ 2, 23, 24, 27, 31, 37 

origin -------------------------------------- 23 

western Sadlerochit Mountains section ________ 7 

Dukhan Field, Qatar ---------------------------- 37 

Dunham, R. J., cited -------------------------- 3, 16 

Dunham classification, carbonate rocks ________ 3, 16 

Dunnington, H. V., cited ------------------------ 37 

E 

East Topagoruk well ---------------------------- 15 

Eastern Sadlerochit Mountains section __________ 3, 27 

Alapah Limestone -------------------- 12, 13, 23 

algal mats ------------------------------ 21, 23 

basal unit -------------------------------- 8, 10 

depositional environments ____________ 8, 9, 10, 11 

dolomite ------------------------------------ 23 

grainstone and packstone unit ________________ 8 

Kayak(?) Shale------------------------------ 12 macrodolomite unit_ _______________________ 8, 23 

microdolomite ------------------------------ 23 

microfossil list ------------------------------ 12 

oolitic grainstone unit ____________________ 9, 11 

pellet wackestone and packstone unit __________ 9 

68A-4N4B ---------------------------------- 3 Wahoo Limestone ____________________________ 14 

Echinoderm, trabeculae-------------------------- 30 

Echinoderm plates ____________________ 27, 28, 29, 30 

nucleation ------------------------------ 29, 30 

Echinoderms __________________ 17, 18, 21, 26, 27, 28 

Echooka Member, Sadlerochit Formation __________ 14 

Sadlerochit Formation, basal beds ____________ 14 

Endicott Group---------------------------------- 10 

Endicott Mountains ------------------------------ 2 

Environments, depositional ---------------- 1, 10, 21 

Epitaxis ---------------------------------------- 20 

Ernst hypothesis -------------------------------- 30 

Evamy, B. C., cited ------------------------------ 27 

F 

Fabric, annealed 35,36 

aragonite ---------------------------------- 37 

calcite ____________________________ 16, 33, 36, 37 

changes, Old Man Creek section ______________ 35 

chert------------------------------------ 28, 36 

dolomite -------------------------------- 22, 37 

grain------------------------------------ 10, 33 

granulation -------------------------------- 35 

limestone ________________________ 16, 21, 33, 35 

lineated ------------------------------------ 33 

Lisburne Group ______________________ 22, 36, 37 

marble______________________________________ 33 

metamorphic __________________________ 2, 7, 38 

neomorphic__________________________________ 22 

oolite skins __________________________________ 19 

recrystallized________________________________ 33 

thermal alteration __________________________ 35 

thrust ________________________ 10, 33, 34, 36, 38 

Faunal lists ------------------------------------ 12 

Fecal pellets ---------------------------------- 6, 20 

Ferric oxide ------------------------------------ 24 

Ferrous iron ________________________________ 26, 27 

Field descriptions, sections ________________________ 3 

Flint____________________________________________ 29 

Florida, limestone ------------------------------ 32 

Folk, R. L., cited -------------------------------- 16 

Foraminifera ______________________ 3, 18, 19, 20, 29 

Foraminiferal samples ____________________________ 2 

Foraminiferal zones __________________________ 2, 26 

Fossil debris ------------------------------------ 37 

Franklin Mountains __________________________ 15, 31 

Franklin Mountains section, dolomite ____________ 31 
Page 

G 

Gigas Beds, northwest Germany _________________ 32 

Glacial gravel, Pleistocene ________________________ 1 

Glaciers, Pleistocene ____________________________ 16 

Glaurus thrust ---------------------------------- 34 

Grain-contact rocks, sparry calcite cement ________ 21 

Grain fabric ______________________________ 10, 33, 35 

Grains _________________________________________ 17 

calcite -------------------------------------- 33 

dolomite -------------------------------- 23, 24 limestone ________________________________ 16,17 

Lisburne Group ______________________ 17, 22,24 

macrodolomite __________________________ 22, 23 

marble-------------------------------------_ 32 microdolomite ____________________________ 22, 23 

neomorphism________________________________ 22 

Grainstone ______________________ 3, 8, 11, 20, 21, 37 

bioclastic ________________________________ 11, 24 

cementation ________________________________ 21 

crinoid ______________________________________ 10 

bryozoan ____________________________ 4, 6, 7 

dolomitic ------------------------------------ 8 

pellet ---------------------------------- 10 

oolitic __________________________ 8, 9, 11, 19, 21 

oolite pellet, dolomitized ____________________ 32 

pellet ________________________________ 8, 20, 32 

crinoid _________________________________ 8 

Plunge Creek section_________________________ 6 

Wahoo Limestone ________________ 19, 21, 23, 24 

western Sadlerochit Mountain section ________ 21 

Graphic registry, sections ________________________ 15 

Greenstone _____________________________________ 9 

H, I,J 

Halimeda __________ _________________ 20 

Hatteras Abyssal Plain __________________________ 30 

Helvetic Alps, eastern Switzerland ________________ 34 

Hole SA, Deep Sea Drilling Project_ _______________ 30 

Ikiakpuk section, depositional environment_ _______ 10 

(68A-1 l ------------------------------------ 10 

Interstitial water _________________ 22, 24, 25, 29, 35 

Introduction-------------------------------------- 1 

Invertebrate skeletons, calcium carbonate, organic content ________________________________ 20 

Iron -------------------------------------- 9, 21, 37 distribution ________________________________ 26 

ferrous _________________________________ 26, 27 

Jura, French------------------------------------ 20 Jura, German ________________________ 26 

K 

Katakturuk Dolomite ______________________ 6, 10, 13 

Katz, A., cited ____________________________ 24, 25, 26 

Kayak Shale ------------------------------------ 1 

Kayak(?) Shale ________________________ 3, 6, 10, 14 

age _____________________________ _ 12 

coal seams __________________________________ 15 

corals -------------------------------------- 12 

depositional environment ____________________ 10 

eastern Sadlerochit Mountains section ________ 12 

microfossils ________________________________ 12 

Old Man Creek section __________________ 10, 12 

Plunge Creek section ________________________ 12 

thickness-------------------------------- 12, 13 

western Sadlerochit Mountains section __ 6, 12, 13 

Kayak(?) Shale-Alapah Limestone 

boundary---------------------------- 10 

Kazan age, brachiopod fauna ____________________ 14 

Kekiktuk Conglomerate ______________________ 3, 12 

thickness____________________________________ 12 

Killik River region ________________________________ 2 

Krynine, P. D.,cited ______________________________ 16 

Kuwait ______________________ _ _______________ 27 

L 

Land, L. S .. cited _______________________________ 21 

INDEX 

Page 

Limestone, annealed _________________________ 35, 36 

Arabian Gulf, porosity ______________________ 21 

aragonitic __________________________________ 16 

bioclastic____________________________________ 29 

calcitic ---------------------------------- 16, 32 

cement ---------------------------------- 16,20 

dolomitic ____________________________________ 3 

fabric modification ____________________ 33, 34, 35 

fabrics ___________________________ 16, 21, 33, 35 

Florida, Pleistocene _________________________ 32 

grains ---------------------------------- 16,17 

intragranular chert, origin __________________ 29 

lineated ------------------------------------ 33 matrix __________________________________ 16,22 

monomineralic ________________________ · ______ 16 

North America, porosity ______________________ 21 

pellet -------------------------------------- 31 

recrystallized________________________________ 32 

granulation ____________________________ 35 

origin __________________________________ 34 

rock types ---------------------------------- 16 

sedimentary ___________________________ 33, 35 

recrystallized____________________________ 32 

strontium content_ ___________________________ 32 

subdivisions ________________________________ 16 

Limestones, Arabian Gulf ________________________ 21 

classification _______________________________ 16 

deposition, cratonic __________________________ 21 

geologic history ______________________________ 16 

Jurassic, French Jura ________________________ 20 

Lisburne Group __________________________ 2, 37 

metamorphism ______________________________ 26 

New Mexico, Permian ________________________ 21 

nonrecent __________________________________ 16 

Old Man Creek section ______________________ 26 

recent ---------------------------------- 16, 21 

subdivision__________________________________ 16 

Lisburne Formation _____________________________ 1 

Anaktuvuk River valley ______________________ 1 

Lisburne Group ____________________________ 1, 2, 29 

age------------------------------------ 1, 2, 14 

Alapah Limestone ____________ 1, 2, 7, 10, 11, 15 

algal-mat dolomites __________________________ 31 

anhydrite __________________________________ 31 

annealed fabrics __________________________ 35, 36 

barite -------------------------------------- 32 

bioclastic debris __________________ 6, 9, 17, 18, 28 

biostratigraphy ______________________________ 12 

bryozoa __________________________________ 18, 37 

carbonate rocks __________________ 14, 16, 27, 37 

celestite ____________________________________ 31 

central Brooks Range ______________________ 2, 14 

chert __________________________ 2, 28, 29, 30, 37 

corals ---------------------------------- 12, 18 

correlation chart, regional ___________________ 12 

crinoids-------------------------------- 6, 8,17 

dedolomites ____________________________ 25, 26 

depositional environments ______________ 1, 10, 21 

dolomites _______________ 2, 23, 24, 27, 31, 37 

eastern Brooks Range _____________________ 2, 14 

Endicott Mountains __ _ ______________ 2 

fabric ________________________________ 22, 36, 37 

faunal lists _________________________________ 12 

Foraminifera _______________________ ___ 18, 19 

Franklin Mountains _______________________ 31 

geologic history ------------------------------ 1 grains _______________________________ 17, 22, 24 

grainstones __________________________ 21, 27, 37 

iron distribution ______________________ 26, 27, 28 

Killik River-Mount Bupto Region _______________ 2 

limestones-------------------------------- 2, 37 porosity ___________________________ 1, 28, 37 

macrodolomites __________________________ 24, 37 

microfossil assemblages _______________________ 2 

microfossil lists ______________________________ 12 

mineral accessories __________________________ 31 

mineralogy----------------------------------- 36 neomorphic fabrics __________________________ 22 

Old Man Creek section ______________________ 10 

oolites ------------------------------ _________ 19 

45 

Page 

Lisburne Group--Continued 

original mineralogy-------------------------- 21 

outcrops, Brooks Range ---------------------- 1 

outcrops, North Slope ------------------------ 1 

outcrops, Sadlerochit Mountains ____________ 1, 31 

Paleozoic sequence ____________________________ 2 

pellets ___________________ · ___________________ 20 

petrographic studies ________________________ 2, 3 

Plunge Creek section, basal unit ______________ 3 

postdepositional alteration __________________ 36 

primary pore space -------------------------- 21 

Sadlerochit Mountains __________ 2, 24, 25, 31, 36 

sedimentary breaks __________________________ 21 

Shainin Lake area---------------------------- 1 

silica, source -------------------------------- 30 

sparry calcite cement ________________ 21, 36, 38 

subsurface-------------------------------- 1, 31 

sulfates ------------------------------------ 31 

Sunset Pass section __________________________ 31 

thickness ------------------------------------ 3 

Wachsmuth Limestone_____________________ 1, 2 

Wahoo Limestone ________________ 2, 7, 11, 13, 14 

western Sadlerochit Mountains section _______ 26 

Lisburne Hills ---------------------------------- 15 thrust sheets ________________________________ 15 

Lithification __________________________ 15, 22, 23, 30 

Lithoclasts -------------------------------------- 15 

Lithologic samples-------------------------------- 2 

Lithostrotionoid corals __________________________ 12 

Locations, stratigraphic sections __________________ 15 

M 

Macrodolomite ______________ 3, 4, 6, 8, 10, 22, 23, 31 

Lisburne Group __________________________ 24, 37 

Old Man Creek section _________________ ---- 23 

origin __________________________ __ 24 

Plunge Creek section ______________________ 4, 23 

rhombs ---------------------------- ________ 23 

syngenetic _________________________________ 22 

zoning -------------------------------------- 24 Magnesium __________________________________ 16, 36 

source, dolomite ___________________________ 30 

Magnesium ions____________________ 26, 28 

Mahmal Formation, southern Israel ____ 23, 26 

Mamet, B. L., cited _ ______________ _ 2, 12, 26 

Maps, lithofacies ___________________________ 14, 15 

Marble ____________________________ 7, 10, 22,32, 38 

associated dolomites _____________________ 35 

calcite, pure -------------------------------- 32 

fabric types _________________ _ ________ 33 

granoblastic-polygonal ________ _____________ 33 

metamorphism _______________________ 7, 33, 34 

mode of origin ___ __________________ __ 33 

Old Man Creek section 32, 33 

recrystallized_______________________ ________ 10 

western Sadlerochit Mountains section ________ 32 

Matrix_----------------------------------------- 22 

Megafossils______________________________________ 12 

Meramecian transgression______________________ 10 

Metamorphic fabrics ________________________ 2, 7, 38 

Metamorphism, limestones ______________________ 26 

marble ________________________________ 7, 33, 34 

thrust movement ____________________ 22, 34, 35 

Meteoric waters ______________________________ 21, 26 

Micrite ---------------------------------- 22, 26, 27 ancient ____________________________________ 22 

porosity ________________________________ 22 

crystal size---------------------------------- 22 

ferrous iron -------------------------------- 27 inclusions __________________________________ 29 

permeability -------------------------------- 22 

porosity ------------------------------------ 22 

Micrite envelopes ______________________ 18, 21, 29, 36 

Microdolomite ________________________ 10, 22, 23, 31 

anhydrite ---------------------------------- 31 celestite ____________________________________ 31 

Old Man Creek section __________________ 10, 23 

Plunge Creek section ________________________ 23 
46 

Page 

Microdolomite-Continued 

Wahoo Limestone ______ _ ------ 23 

westem Sadlerochit Mountains section _______ 23 

Microfacies -------------------------------------- 2 

Microfossil, assemblages __________________________ 2 

lists _ ___ __ ___ __ __ _ _ _ _ __ __ __ _ ___ __ __ ___ ___ __ _ 12 

zones ------------------------------ 2, 3, 10, 12 

Microfossils ________ _ _____________________ 2, 12 

Meramecian age ________________________ 12, 13 

Minagish Oolite, Kuwait ________________________ 27 

Mineralogy, Lisburne Group ______________________ 36 

Mitterer, R. M., cited ____________________________ 20 

Mollusks---------------------------------------- 20 dominant amino acids _______________________ 20 

Monterey Formation, Califomia __________________ 30 

Monterey porcellanite ___________________________ 30 

Morlot, A., von, cited ________________________ 25 

Morrowan transgression __________________________ 11 

Morrowan-Atokan boundary ______________________ 11 

Mount Bupto region _____________________________ 2 

Mount Michelson_____________________________ 9, 33 

Mount Michelson pluton ______________________ 9, 10 

age ---------------------------------------- 35 

emplacement___ _ _________________ 26 

Mudstone __________________________________ 3, 8, 37 

lime ------------------------------------ 10, 30 

Mud-supported rocks, sparry calcite'cement_ _______ 21 

N 

Naval Petroleum Reserve No.4, aeromagnetic data 15 

carbonate rocks ______________________________ 15 

seismic data _______ 15 

Neomorphic fabrics_________________________ 22 

Neomorphic processes _______________________ 22, 37 

Neomorphic spar ________ _ ______ 22 

Neruokpuk Formation___ _ __________ 3, 8, 10, 12, 13 

age __ __ __________________ _______ 13 

clastic rocks ----------------------------- 14 

New Mexico, limestones__ _______________ 21 

Nodules, anhydrite _ 31 

North Slope ---------------------------------- 1, 15 

Northeastem Brooks Range sections _ _ __ 1 

0 

Old Man Creek, outcrops ___________________ 10 

Old Man Creek area ______________________ 10, 11, 14 

Old Man Creek section ________________ 3, 9, 33 

Alapah Limestone ________________________ 13, 23 

basal unit ______ ________________ 10 

crinoid wackestone unit ______________________ 10 

dedolomite ---------------------------------- 25 

depositional environment _ 10 11 

dolomite------------------~~~~~~~~~~~~~~~- 3: 23 

dolomitic pellet packstone and grainstone unit__10 

fabric changes ------------------------------ 35 

Kayak(?) Shale __________________________ 10, 12 

limestone, recrystallized, origin ______________ 34 

limestones ________________________________ 26 

Lisbume Group ______________________________ 10 

macrodolomite beds __________________________ 23 

marble _____ ___________ ____ 32 33 

microdolomite unit ______ --------~~~~--- 10: 23 

microfossil list ------------------------------ 12 

recrystallization ------------------------------ 3 

69A-4/4k __________________________ 3, 9, 23, 26 

stress anomaly ____________________________ 35 

Wahoo Limestone ________________________ 10, 14 

Oolite---------------- 4, 6, 8, 9, 17, 19, 26, 27, 36,37 

calcium carbonate, organic content_ ___________ 20 

carbonate mud ------------------------------ 19 

cementation _______________________________ 19 

core _ __ __ _ _ __ __ __ _ _ __ __ _ __ ___ __ __ __ _ ___ __ ___ 19 

dominant amino acids ________________________ 20 

fabric, origin -------------------------------- 19 

radial ---------------------------------- 19 formation __________ ____________________ 19 

classical hypothesis ______________________ 20 

INDEX 

Page 

Oolite, formation-Continued 

mechanism_______________ _ ______ 20 

Lisbume Group ______________________________ 19 

organic matrix ______________________________ 20 

skins _____________________________ 9, 19, 21, 32 

snowball mechanism ________________________ 20 

Wahoo Limestone_ 

Oolitic debris __ 

27 

26 

Oolitic packstone _______________________________ 9 

Organosilicic acids ____ _ ______________ 30, 31 

Osagia______________________________________ 9, 19 

Outcrops, Lisbume Group______ _ ______ 1, 31 

Old Man Creek__ _ ____ 10 

p 

Pacific, South ________ _ ---------------- 29 

subarctic__________ _ _______________ 29 

Packstone _________________________ 4, 6, 7, 8, 33, 37 

bryozoan crinoid ______________________________ 7 

pellet ------------------------------------ 9, 20 

bioclastic________________________________ 33 

bryozoan _______________________________ 7 

dolomitic________________________________ 10 

oolitic________________________________________ 9 

Plunge Creek section ________________________ 23 

western Sadlerochit Mountains section ________ 7 

Paleoecology, Wahoo Limestone ____________________ 2 

Paris Basin, limestone, comparable to Lisburne 

Group ______________________________ 21 

Pelecypod shells, aragonitic ______________________ 36 

Pelecypods ____________________ 18, 19, 20, 26, 29, 36 

fibrous ____________________________ 18, 28, 30, 37 

Pelletoid debris __________________________ 26, 27, 36 

Pellets ____________________________ 4, 6, 7, 8, 17,20 

Lisbume Group ______________________________ 20 

Wahoo Limestone___________________________ 20 

Pennsylvanian transgression ____________________ 11 

Petrographic studies ____________________________ 2, 3 

Petrography, carbonate _____________________________ 2 

sections-------------------------------------- 3 

Philip Smith Mountains ______________________ 14, 15 

Pleistocene limestone, Florida ____________________ 32 

Plunge Creek section __________________________ 3, 25 

Alapah Limestone ____________________ 13, 22, 23 

Alapah Limestone-Kayak(?) Shale boundary __ 10 

basal unit------------------------------------ 3 

bryozoan crinoid packstone unit_ _______________ 6 

crinoid bryozoan grainstone to packstone sequence_ 4 

dedolomitization zone ________________________ 26 

depositional environment _________ 4, 6, 10, 11, 23 

dedolomitization ____________________________ 11 

dolomite ________________________________ 3, 4, 23 

dolomite units ______________________________ 23 

dolomitic wackestone and packstone unit ______ 4 

grainstone unit ______________________________ 6 

Kayak(?) Shale ______________________________ 12 

Kekiktuk Conglomerate ______________________ 12 

Lisburne Group ------------------------------ 3 

macrodolomite unit_ _______________________ 4, 23 

microdolomite ______________________________ 23 

microfossil list ------------------------------ 12 

packstone ---------------------------------- 23 

70A-4/5 -------------------------------------- 3 

upper unit ---------------------------------- 23 

wackestone__________________________________ 23 

Wahoo Limestone ____________________________ 14 

westem Sadlerochit Mountains section correlative_ 3 

Point Barrow------------------------------------ 15 

Porcellanite ------------------------------------ 30 

Monterey ---------------------------------- 30 

Pore waters, chemistry __________________________ 28 

diagenetic ---------------------------------- 32 

silica------------------------------------ 29, 30 

strontium ---------------------------------- 32 

Porosity, limestone, Lisbume Group ________ 1, 28, 37 

limestone, North America ____________________ 21 

micrite______________________________________ 22 

Potassium ferricyanide stain ____________________ 26 

Previous work------------------------------------ 1 

Page 

Protodolomite __________________________________ 23 

Purdy, E. G., cited ------------------------------ 15 Pyrite____________________________________________ 9 

Pyroclastic rocks -------------------------------- 10 

Q,R 

Qatar, Arabian Gulf ____________________________ 23 

Quartz------------------------------------ 8, 24, 30 fine-grained ____________________________ 7, 8, 10 

polycrystalline_ _ ___ _____ _____ __ ___ ___ __ _____ _ _ 6 

Radiolaria ---------------------------------- 29, 30 Rock types, sections ______________________________ 3 

Rugose corals____________________________________ 12 

s 

Sabkha, Arabian Gulf__ _ _ ______________ 23, 31 

coastal ------------------------------- 21, 23, 32 

sedimentation ____________________________ 32, 37 

Trucial Coast_ _______________________________ 32 

Sadlerochit Formation ________________________ 10, 14 

brachiopod fauna ____________________________ 14 

Echooka Member ____________________________ 14 

unconformity-------------------------------- 14 

Sadlerochit high __________________________ 10, 14, 15 

Sadlerochit Mountains ________________________ 10, 14 

carbonate rocks, sections __________________ 1, 10 

Carboniferous carbonate rocks, regional relations ________________________________ 14 

eastem, Sunset Pass, 68A-4A/4B ______________ 8 

Lisbume Group ________________ 2, 24, 25, 31, 36 

outcrops ------------------------------ 1, 31 

sections ______ -------------------------------- 1 

Wahoo Limestone ---------------------------- 2 

westem, 69A-1 ____________________________ 3, 6 

Sea, epicontinental ------------------------------ 28 

Sea level, variation, Holocene ____________________ 15 

Sea water, Arabian Gulf ________________________ 21 

calcium carbonate ____________________ 20, 21, 27 

normaL_____________________________________ 29 

silica content_ _______________________________ 29 

Section, eastem Sadlerochit Mountains ________ 3, 27 

Old Man Creek ________________________ 3, 9, 33 

Plunge Creek ____________________________ 3, 25 

westem Sadlerochit Mountains ____________ 3, 32 

Sections, Brooks Range, northeastem ______________ 1 

correlation ______________________________ 10, 12 

depositional environments ____________________ 10 

depths -------------------------------------- 3 

description ---------------------------------- 3 

diagenetic processes __________________________ 1 

field descriptions ______________________________ 3 

graphic registry ____________________________ 15 

petrography---------------------------------- 3 

rock types------------------------------------ 3 Sadlerochit Mountains _______________________ _ 

sedimentation history ________________________ 1 

subdivisions---------------------------------- 3 

Sedimentation, calcareous, continuous ____________ 21 

clastic -------------------------------------- 20 

history -------------------------------------- 1 

Sediments, algal mat __________________________ 8, 32 

interstitial waters __________________________ 29 

sabkha---------------------------------- 32, 37 

siliceous ------------------------------------ 29 

Shainin Lake area-------------------------------- 1 

Shark Bay, Westem Australia ________________ 18, 22 

Shublik Mountains ------------------------------ 14 

Silica------------------------------------ 28, 29, 30 

cryptocrystalline ---------------------------- 31 

crystallites---------------------------------- 29 

fibrous-------------------------------------- 29 

gels ---------------------------------------- 29 Lisbume Group ______________________________ 30 

opaline______________________________________ 29 

poikilotopic_______ __________ ___ ___ __ _________ 31 

pore waters------------------------------ 29, 30 

recrystallization, rate------------------------ 30 

sea water ---------------------------------- 29 

source -------------------------------------- 29 
Page 

Silica-Continued 

sponge spicules ____________________________ 9, 30 

Siliceous oozes, Antarctic belt -------------------- 29 

Silicic acid-------------------------------------- 29 

Sinclair/British Petroleum Colville No. 1 well ____ 15 

Skeletons -------------------------------------- 37 

aragonitic ---------------------------------- 32 

calcitic______________________________________ 30 

crinoid______________________________________ 30 

siliceous -------------------------------- 29, 30 

South Pacific------------------------------------ 29 

Spar, neomorphic, operational criteria ____________ 22 

Sponge debris ---------------------------------- 30 

Sponge spicules ------------------------------ 9, 30 

ghosts ------------------------------------ 4, 6 

Sponges ---------------------------------------- 29 Spry, A., quoted ______________________________ 32, 33 

Stratigraphic sections, correlation ____________ 10, 12 

depositional environments ____________________ 10 

foraminiferal zones _________________________ 2, 26 

graphic registry ---------------------------- 15 

locations------------------------------------ 15 

maps -------------------------------------- 15 

sampling ------------------------------------ 2 Stress fields __________________________________ 35, 36 

Strontium, calcitic limestone ____________________ 32 

calcitic limestone, Florida ____________________ 32 

coprecipitation ------------------------------ 32 

dolomite ------------------------------------ 32 

Study method ------------------------------------ 2 Sulfates __________________________________ 24, 31, 32 

Sunset Pass, eastern Sadlerochit Mountains, 

68A-4A/4B __________________________ 8 

Sunset Pass section, Lisburne Group, dolomites ____ 31 

T,U 

Tectonic activity ________________________ 9, 21, 36, 38 

INDEX 

Page 

Thermal metamorphism ---------------- 9, 10, 34, 35 

Thrust fault ---------------------- 10, 33, 34, 36, 38 Thrust sheets ______________________________ 7, 10, 15 

Tillman, R. W., cited ---------------------------- 19 Topagoruk well __________________________________ 15 

Trucial Coast, Arabia ________________________ 19, 32 

Turnbull's blue pigment_ _________________________ 26 

Unconformity surface---------------------------- 26 

Union Oil Kookpuk No. 1 well ____________________ 15 

United States Navy wells ------------------------ 15 

W,Y 

Wachsmuth Limestone----------------------------

Lisburne Group ---------------------------- 1, 2 

Wackestone------------------------------ 3, 6, 7, 37 

bryozoan crinoid------------------------------ 7 

crinoid-------------------------------------- 10 

iron-rich------------------------------------ 32 

pellet ------------------------------------ 9, 20 

Plunge Creek section ------------------------ 23 

western Sadlerochit Mountains section ________ 7 

Wahoo Limestone ________________________ 2, 7, 10, 14 

age -------------------------------------- 2, 14 

basal unit ------------------------------ 7, 8, 9 

biostratigraphy ------------------------------ 2 

coral fauna ------------------------------ 2, 12 

eastern Sadlerochit Mountains section ________ 14 

grainstone units, dolomite ____________________ 23 

grainstones ------------------------------ 21, 24 

oolitic ------------------------------ 19, 21 

Lisburne Group __________________ 2, 7, 11, 13, 14 

lower unit ---------------------------------- 11 

microdolomite ------------------------------ 23 

Old Man Creek section __________________ 10, 14 

oolite units __________________________________ 27 

paleoecology---------------------------------- 2 

pellets -------------------------------------- 20 

47 

Page 

Wahoo Limestone--Continued 

Plunge Creek section ------------------------ 14 

Sadlerochit Mountains------------------------ 2 

unconformity-------------------------------- 14 upper unit_ ___________________________________ 7 

Wahoo Limestone-Alapah Limestone, boundary 11,34 

Walls, R., cited ---------------------------------- 2 

Water, connate---------------------------------- 30 pore, diagenetic ______________________________ 32 

Watson, Janet, Dr., cited ------------------------ 34 

Well, barite ------------------------------------ 32 

Wells, anhydrite -------------------------------- 31 

celestite ------------------------------------ 31 

exploration ------------------------------ 14, 15 

Western Sadlerochit Mountains __________________ 10 

69A-1 ------------------------------------ 3, 6 

Western Sadlerochit Mountains section ________ 3, 32 

Alapah Limestone -------------------------- 13 

basal unit -------------------------------- 6, 10 

bioclastic grainstone ------------------------ 24 

dedolomitization---------------------- 11, 25, 26 

depositional environments ________ 6, 7, 8, 10, 11 

dolomite ------------------------------------ 23 

fabric changes ------------------------------ 35 

grainstones _____________ ---------- ___________ 21 

Kayak(?) Shale------------------------ 6, 12, 13 

limestone, recrystallized, origin ______________ 34 

Lisburne Group ______________________________ 26 

lower limestone unit-------------------------- 6 marble ______________________________________ 32 

marble unit ------------------------------ 7, 10 

microdolomite ------------------------------ 23 

microfossil list ------------------------------ 12 

packstones ---------------------------------- 7 wackestones _________ ______ __________ ______ ___ 7 

Wahoo Limestone ------------------------ 7, 14 

Wood, George, cited ------------------------------ 2 

Yule Marble, recrystallization-------------------- 35 

--tf U.S. GOVERNMENT PRINTING OFFICE : 1975 0-573-516 

PLATES 1-12 
PLATE 1 

FIGURE 1. Oolitic bioclastic grainstone, 70A-5, 1,988 feet, x 65. Thin oolitic skins show both radial 

and concentric structure around bioclasts, some of which are crinoid debris. In 

contrast to figure 3, however, the less equant debris has no oolitic coating. Two 

phases of cement are present. 

2. Oolitic grainstone, 69A-1, 1,385 feet x65. Thin oolitic skins developed around bioclastic cores of diverse shapes. The cores range from equidimensional crinoid plates to 

bryozoan clasts to elongate pelecypod fragments. The intergranular space has been 

filled with sparry calcite. 

3. Oolitic grainstone, 69A-1, 340 feet, x65. The oolitic coatings developed around nucleii 

of either crinoid or bryozoan clasts. The foraminifer on the left of the field has no 

oolitic coating. Two generations of sparry calcite cement are shown. The first, a 

fibrous coating perpendicular to the edges of the oolite grains, is iron-free calcite; the 

second, occupies the intergranular pore space, is equant iron-rich calcite crystals. 

4. Oolitic packstone and grainstone, 68A-4A, 1,180 feet, x65. The skin of the central 

oolite is displaced from the original core. The outer part of the core was presumably 

dissolved, after which the iron-poor first-phase sparry calcite cement was deposited 

with a radial fabric on the inner surface of the oolitic coating. A fracture then 

transected the lower part of the oolite and caused the oolitic skin to be partly ripped 

away from the core. The remainder of the original core space and the new void caused 

by the movement of the oolite skin away from the core were then filled with iron-rich 

second-phase sparry calcite cement. 

5. Oolitic grainstone, 68A-4A, 1,090 feet, x 65. Developement of thin oolitic coatings with 

radial texture around irregular pellet and bioclastic debris. Two phases of sparry 

calcite cement are clearly distinguishable-first, an iron-free fringe around the 

grains, and second, an iron-rich phase filling the intergranular spaces. 

6. Bioclastic grainstone with pelecypods and bryozoans, 70A-5, 1,910 feet, x33. Fragment of pelecypod shell with internal divisions preserved by micritic partitions at 

right angles to the shell wall. The outline of the shell is preserved by a micrite 

envelope. Two generations of sparry calcite are observable. In the first phase, a thin 

layer of prismatic calcite probably grew to the outer shell wall that was originally 

aragonite; the calcite and the micrite envelope gave the shell sufficient rigidity to 

withstand compaction when the original aragonite wall dissolved. 

The second-phase cement may have entered the cast by the upper break in the 

skeleton wall (boring?) and, in the left hand part of the skeleton, appears to have 

displaced the partitions from the upper shell wall. The second-phase cement has 

equant crystals that transect the shell partitions. 

7. Bryozoan crinoid grainstone, 70A-5, 2,450 feet, X33. Hexagonal syntaxial overgrowth 

of sparry calcite on crinoid plate. Lines of inclusions show the progressive development of the overgrowth. 

8. Bryozoan crinoid grainstone, 70A-5, 2,430 feet, x33. Echinoderm spine set in a sparry 

calcite cement. Probable micrite envelope. The microstructure of the spine has been 

preserved (see left of field). 
GEOLOGICAL SURVEY 

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t.f.'t 

~ 

PROFESSIONAL PAPER 857 

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:·....:r.., "'" -

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6 

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,'1 ~ I' • . 

"' 

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OOLITE BIOCLASTIC GRAINSTONE, OOLITIC GRAINSTONES, OOLITIC PACKSTONE/GRAINSTONE, BIOCLASTIC 

GRAINSTONE, AND BRYOZOAN CRINOID GRAINSTONES 
PLATE 2 

FIGURE L Bryozoan grainstone, 70A- 5, 2,465 feet, x33. The zooecia (cavities) of bryozoan fronds 

are completely filled with sparry calcite. 

2. Bryozoan grainstone, 70A-5, 2,070 feet, x33. Well-packed assemblage of elongate 

bryozoan fronds whose zooecia are filled with sparry calcite cement. 

3. Dolomitic bryozoan grainstone, 68A-4A, 1,260 feet, x65. The bryozoan zooecia are 

filled with carbonate mud in which dolomite rhombs are developed. A pelecypod cast 

(lower right) has been enclosed by a micrite envelope and adjacent to the shell wall 

the internal texture of the sparry calcite is prismatic and becomes equant in the 

center. This texture is typical of deposition from solution. 

4. Bryozoan grainstone, 69A-1, 1,182 feet, x65. Large fragment of a bryozoan frond in 

which the acanthopores (interwall spaces) are filled with sparry calcite cement but 

the zooecia are lined with carbonate mud with a central development of sparry 

calcite, probably of neomorphic origin. The fabric of the sparry calcite in the zooecia 

has possibly been affected by the organic matter originally occupying this space. 

5. Microdolomite, 70A- 5, 2,090 feet, x 65. Bryozoan fragment set in a microdolomite host. 

The zooecia are filled with sparry calcite. The microdolomite is probably of very early 

diagenetic origin but has not replaced the bryozoan fragment to any extent. 

6. Bioclastic microdolomite, 68A-4A, 1,100 feet, x65. Individual rhombs of dolomite are 

stained by iron oxide. The dolomite almost certainly replaces original calcite mud but 

also fills bryozoan zooecia and marginally replaces the bioclastic skeletons. 

7. Dolomitic crinoid bryozoan packstone, 68A- 4A, 940 feet, x33. Rhombs of dolomite 

(=100JLm) restricted to the carbonate mud matrix and outlined by iron oxides. 

8. Dolomitic bryozoan packstone, 69A- 1, 797 feet, x 100. Bryozoan fronds filled with 

carbonate mud in which dolomite rhombs are developed. Individual rhombs contain 

an iron-oxide zone toward the outer margin parallel to the rhomb faces. The dolomite 

is iron poor. 
GEOLOGICAL SURVEY 

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BRYOZOAN GRAINSTONES, DOLOMITIC BRYOZOAN GRAINSTONES, MICRODOLOMITE, BIOCLASTIC MICRODOLOMITE, DOLOMITIC CRINOID BRYOZOAN PACKSTONE, AND DOLOMITIC BRYOZOAN PACKSTONE 
PLATE 3 

FIGURE 1. Bioclastic grainstone, 69A- 4, 1160 ft, x65. Bryozoan fragments set in sparry calcite. 

Original dolomite partly replaced by calcite in rhombs outlined by iron oxides. 

2. Macrodolomite, 69A-4, 940 ft, x65. Macrodolomite with yellow (phosphatic?) cores, 

and compound vein with coarsely crystalline dolomite at the center and quartz on the 

edges. This sample suggests that a fracture first was filled with quartz and upon later 

dilation was filled with dolomite. 

3. Macrodolomite, 70A- 4, 15 ft, x65. Anhedral macrodolomite with intergranular 

hematitic clay. 

4. Macrodolomite, crossed nicols, 69A-4K, 145ft beneath base ofLisbume Group, x80. 

Anhedral grains of macrodolomite with no intergranular porosity. 

5. Microdolomite, subsurface, x 50. A bryozoan (stained by Alizarin RedS) set in a matrix 

ofmicrodolomite. The woecia of the bryozoan are largely filled with dolomite and the 

extemal margins are partly replaced. Traces of unreplaced bryozoa that are scattered throughout the dolomite demonstrate large-scale replacement of skeletal matter. 

6. Macrodolomite, 70A-4, 720 feet, x65. Anhedral macrodolomite with iron-rich cores 

(stained by potassium ferricyanide) and later iron-free rims. 

7. Macrodolomite, 70A-4, 125 feet, x65. Macrodolomite rhombs with cloudy cores and 

clear rims. The cores tend to be iron rich and the rims iron poor. 

8. Microdolomite with clot of iron oxide, 69A- 1, 593 feet, x65. In the bulk of the rock 

individual rhombs are wned with a cloudy iron-rich core and an iron-poor outer zone. 

In contrast, the rhombs within the clot have an intemal zone of iron oxide parallel to 

the rhombic faces, and the dolomite is iron poor. The iron oxides in the clot may have 

originated from an original unstable iron-rich dolomite, whereas outside the clot the 

iron-rich dolomite core has remained stable and iron oxides are absent. The outer 

iron-free dolomite appears to be a ubiquitous later phase in both the clot and the host 

rock. 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 857 PLATE 3 

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BIOCLASTIC GRAINSTONE, MACRODOLOMITE, MICRODOLOMITE, MICRODOLOMITE WITH CLOT OF IRON OXIDE 
PLATE 4 

FIGURE 1. Macrodolomite, 69A- 1, 375ft, x65. Zoned rhombs ofmacrodolomite with interrhombic 

iron oxide. 

2. Iron-rich dolomite, 69A-1, 60 feet, x33. Typical view illustrating crosscutting relation 

between sparry calcite cement (above) and earlier dolomite. In the center of the field 

is a dolomite rhomb with a dedolomitized zone of calcite parallel to the rhomb faces, 

and immediately below is an iron-rich dolomite with no apparent zonation. This 

whole zone of early dolomite is rich in iron oxide. 

3, 6. Dolomitic bioclastic grainstone, 69A- 1, 455 feet, x65. Rhombs of iron-poor dolomite 

edged with iron oxide. A thin zone of calcite is developed toward the outer edges of the 

rhombs and parallel to the rhomb faces. Inner parts of rhombs are commonly void, 

probably because of postdedolomitization solution. 

4. Bioclastic grainstone, 69A- 1, 330 feet, x65. The bioclasts have a thin patina (replacive?) of dolomite (shown as a white rim) formed before the sparry calcite cement. 

5. Dolomitic bioclastic grainstone, 69A-1, 465 feet, x65. Scattered intergranular dolomite rhombs, each of which is rimmed by iron oxide. Calcite zones near the outer 

edges and parallel to the rhomb faces were produced by dedolomitization. Centers of 

rhombs are either void or contain partly dissolved dolomite. 

7. Dedolomite, 69A-4, 330 feet, x80. Corroded macrodolomite rhomb with outer dark 

zone replaced by sparry calcite. A calcite-filled veinlet partly transects the rhomb. 

8. Early dolomite, 69A-1, 60 feet, x33. Iron-rich dolomite and partly dedolomitized 

rhombs surrounded by later sparry calcite cement. The margins of the dolomite are 

surrounded by pyrite that probably formed as a residue after the replacement of 

iron-rich dolomite by calcite. 
GEOLOGICAL SURVEY PROf-ESSIONAL PAPER 857 PLATE 4 

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MACRODOLOMITE, IRON-RICH DOLOMITE, DOLOMITIC BIOCLASTIC GRAINSTONE, DEDOLOMITE, EARLY 

DOLOMITE 
PLATE 5 

[All samples from 69A- l , 60ft] 

Frc URE 1. x 32, plane-polarized light. Stained by Alizarin RedS. Rhombs of dolomite set in sparry 

calcite cement. The white zones parallel to the original rhomb faces are calcite 

(dedolomite). Overgrowths of homogeneous dolomite occur in two stages parallel to 

the line of intersection of the rhomb faces. Hematite is developed in patches, some at 

the edge of the original rhomb and included within the overgrowth, and others on the 

outer tdges of the overgrowths. 

2. x 32, crossed nicols. Stained by Alizarin RedS. Same field as above. The original rhomb 

extinguishes in quadrants in continuity with the adjacent dolomite overgrowth. The 

dedolomitized calcite zones are of different optical orientation than the surrounding 

dolomite. 

3. Interpretation of the field represented by 1 and 2 above. The optical continuity of the 

dolomite overgrowth with the adjacent quadrant of the original dolomite rhomb but 

which is independent of the orientation of the dedolomitized zones of calcite is 

considered evidence that dedolomitization took place prior to the overgrowth. 
GEOLOGICAL SURVEY 

DOLOMITE 

OVERGROWTH 

OUTLINE OF 

ORIGINAL RHOMB 

E/Il\(;;;hG] CALCITE WITHIN DOLOMITE RHOMB 

'. 'illl . ,, ') ' ' 

3 

OVERGROWTH IN OPTICAL 

-It---- +- CONT INUITY WITH ADJACENT QUADRANT OF ORIGINAL DOLOMITE 

HEMATITE 

OPTICAL CONTINUITY 

WITH ADJACENT QUADRANl OF ORIGINAL 

DOLOM ITE 

500,um 

DEDOLOMITE WITH ANNOTATED DIAGRAM 

2 
PLATE 6 

FIGURE 1. Bioclastic mudstone, 69A-1, 390 feet, x 65. Crinoid plate set in fine-grained matrix of 

calcite microspar. In the center of the field a crinoid plate has undergone grain 

diminution, especially the original outline and in a central "channel." Adjacent to 

the right side of the original crinoid plate is clear sparry calcite that probably 

represents a relic of the original syntaxial overgrowth. 

2. Pellet intraclast grainstone, 70A-5, 2,045 feet, x 65. A high proportion of the grains 

show heterogeneous internal texture, and at first glance they might be interpreted as 

either reworked carbonate mud or pellets of fecal origin. In the center of the field , 

however, a crinoid plate shows marginal grain diminution, which may account for 

the origin of other grains (for example, the pellets or intraclasts) where the process of 

grain diminution has gone to completion. Two phases of sparry calcite can be observed. 

3. Sheared limestone, 69A- 4, 1,200 feet, x 65. Strong parallel lineation of sparry calcite 

pods and micrite. This structure almost certainly originated from shearing, but 

evidence of annealing is absent. Stylolites in this rock are superimposed on the shear 

fabric. Sparry calcite veinlets transect the shear fabric at 70°. 

4. Shear fabric, marble, 69A- 4, 1,190 feet, x 65. Shear fabric interrupted by a series of 

transverse displacements, in a sparry calrite crystal (probably originally a crinoid 

plate). 

5. Sheared limestone, 69A-4K, 90 feet below base of Lisburne Group, x 65. Sheared 

limestone with argillaceous laminae and scattered coarse pods of sparry calcite. 

6. Marble, 69A- 1, 1,015 feet, x 65. Large dusty twinned calcite crystals replaced by a later 

stage undeformed clear calcite crystal. The margins of individual crystals are crenulated. The clear crystal is probably a product of annealing metamorphism. 

7. Marble, 69A- l , 1,090 feet, x 33. Early twinned calcite, later untwinned calcite probably formed by annealing, and minor grain diminution along the crystal boundaries. 

8. Marble, 69A-1, + 1,130 feet, x33. Large untwinned crystals of calcite of probable 

annealed origin with extensive interpenetration of grain margins and grain diminution concentrated along the major grain boundaries. 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 857 PLATE 6 

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BIOCLASTIC MUDSTONE, PELLET INTRACLAST GRAINSTONE, SHEARED LIMESTONE, SHEAR FABRIC, MARBLE 
PLATE 7 

FIGURES 1- 3. Sequence of diagenetic events x50 subsurface. 1, Plane-polarized light; 2, Crossed 

nicols; 3, Interpretation. For discussion see section on "Time of Origin." 
GEOLOGICAL SURVEY 

3 

PROFESSIONAL PAPER 857 PLATE 7 

FRACTURED BRYOZOAN 

FROND 

RADIAXIAL AND EQUANT 

SPARRY CALCITE PORE FILL 

2 

'c---+-- SYNTAXIAL CALCITE 

I mm 

SEQUENCE OF DIAGENETIC EVENTS 

OVERGROWTH 

LIMIT OF ECHINODERM 

FRAGMENT 

FIBROUS CHALCEDONY 
PLATE 8 

FIGURE 1. Chert, 69A- 4, 340 ft, x80. Chert with ghosts after sponge spicules. 

2. Siliceous lime-mudstone, 69A- 1, 15 feet below base ofLisbume Group crossed nicols, 

x65. Casts after pelecypods infilled with chert showing early radial and final equant 

fabric that probably indicate deposition from solution. 

3. Microdolomite, 70A-4, 1,130 feet, x33. Sponge spicules preserved in chert set in a 

matrix of microdolomite. 

4. Bryozoan crinoid packstone and grainstone, 68A- 4A, 990 feet, x33. The bryozoan 

zooecia (cavities) are patchily filled with and replaced by chert. The sparry calcite 

that also fills parts of the cavities is enriched in iron probably scavenged from the 

replaced calcite. 

5. Calcareous chert, 69A-1, 350 feet, x 33. Bioclasts ofbryozoan and crinoid debris set in a 

matrix of chert. Marginal replacement of the bioclasts is evident but no intragranular chert was recorded in this specimen. 

6. Matrix chert, 68A-4B, 90 feet, x33. Matrix chert with intense marginal corrosion of the 

included bioclasts. 

7. Chert, 70A-4, 1,340 feet, x80. Euhedral and partly corroded dolomite rhombs set in 

chert that is cut by a series of subparallel cracks. 

8. Chert, 70A- 4, 1,185 feet, x33. Chert containing euhedral and corroded macrodolomite. 
GEOLOGICAL SURVEY 

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PROFESSIONAL PAPER 857 PLATE 8 

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CHERT, SILICEOUS LIME-MUDSTONE, MICRODOLOMITE, BRYOZOAN CRINOID PACKSTONE/GRAINSTONE, 

CALCAREOUS CHERT, MATRIX CHERT, CHERT 
PLATE 9 

FIGURE 1. Bioclastic wackestone, 69A- 1, 1,305 feet, x65. Chert developed within a twinned 

crinoid plate and its overgrowth, both set in a carbonate mud matrix. 

2. Crinoid bryozoan grainstone, 68A- 4A, 950 feet, x33. Chert nucleus that developed 

within crinoid ossicle and obliterated the pore pattern. The central canal of the 

ossicle is still visible (just above center of right edge of field). The sparry calcite 

surrounding the ossicle is a good example of a syntaxial overgrowth. 

3. Bioclastic microdolomite, 68A-4A, 1,100 feet, x65. Crinoid plate with intragranular 

development of chert set in microdolomite. Iron-rich macrodolomite rhombs developed at the chert-calcite interface. 

4. Bryozoan crinoid packstone, 68A-4A, 1,625 feet, x33. Crinoid plate with syntaxial 

overgrowth of sparry calcite and a patch of intragranular chert. A reaction rim of 

iron-rich dolomite occurs within the chert at the chert-calcite interface. 

5. Bioclastic packstone,.69A-1 , 352 feet, x65. Pelecypod fragment now almost completely 

internally replaced by intragranular chert. The original curved growth-pattern of 

the pelecypod is preserved in the chert. The crack on the right side of the photograph 

is restricted to the chert and is probably a result of dehydration of porcellanite. 

6. Bioclastic packstone, 69A- 1, 1,320 feet, x65. Intragranular chert developed in crinoid 

plate with well-preserved pore pattern. Carbonate mud matrix. 

7. Dedolomite, 70A- 4, 1,080 feet, x 100. Intergranular rhombs in a crinoid packstone. The 

large central rhomb is only marginally replaced by calcite, but the rhomb to the right 

and the corroded grain above center have been completely replaced by fine-grained 

calcite. 

8. Bioclastic grainstone, subsurface, x50. Crinoid plate with well-developed micrite envelope. Foraminifera (left) and Bryozoa (right) also present. First- and second-stage 

sparry calcite cement are well developed. Within the crinoid plate are chert patches 

surrounded by pin-point aureoles of chert in calcite (only noticeable under crossed 

nicols). 
GEOLOGICAL SURVEY 

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BIOCLASTIC WACKESTONE, CRINOID BRYOZOAN GRAINSTONE, BIOCLASTIC MICRODOLOMITE, BRYOZOAN 

CRINOID PACKSTONE, BIOCLASTIC PACKSTONE, DEDOLOMITE, BIOCLASTIC GRAINSTONE 
PLATE 10 

FIGURE 1. Chert and dolomite, subsurface, x50. Ghost structures of crinoid fragments in chert set 

in a matrix of microdolomite. Preservation of traces of original pores of crinoid plates 

is particularly noteworthy. 

2. Chert and dolomite, subsurface, x50. Ghost structures of mollusk and crinoid fragments developed in chert and set in a matrix of microdolomite. The rock fabric 

suggests that this rock was originally a bioclastic packstone in which the bioclasts 

have been largely replaced by chert while the intergranular calcite mud has been 

replaced by dolomite. 

3. "Osagia" grainstone, 68A-4A, 1,570 feet, x65. Crinoid plate forms nucleus for 

"Osagia." Individual cusplike growth forms now preserved in chert. 

4. "Osagia" grainstone, 68A-4A, 1,580 feet, x 65. Bryozoan fragment forms nucleus for an 

"Osagia" grain. Cusplike growth forms of"Osagia" now largely preserved in chert. 

5. "Osagia" grainstone, subsurface, x65. Compound grains of"Osagia" developed around 

a bioclastic core and set in a sparry calcite cement. The cement has an iron-poor 

fringe and a later iron-rich pore fill. 

6. Argillaceous limestone, subsurface. A variegated bioturbated wackestone and 

packstone. Crinoid debris is abundant, preserved in chert at the top of the specimen 

and preserved in calcite at the base. Except for replacing crinoids, chert is absent from 

the matrix. 
GEOLOGICAL SURVEY PROFESSIONALPAPER857 PLATE 10 

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5 

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CHERT/DOLOMITE, "OSAGIA "GRAINSTONE, ARGILLACEOUS LIMESTONE 
PLATE 11 

FIGURE 1. Barite, subsurface, x33. Euhedral prisms of barite (b) developed as intergranular 

cement in pellet grainstone. 

2. Celestite, subsurface, x33 crossed nicols. Poikilotopic celestite (white) occupying the 

intergranularpore space of a pellet grainstone. The dark intergranular space is void. 

3. Macrodolomite, 70A-5, +1,880 feet, x33. Zoned dolomite rhombs and poikilotopic 

polycrystalline quartz (center). The external morphology of the quartz is analogous 

to that of the original anhydrite nodule. 

4. Anhydrite, subsurface, x33. Anhydrite nodule (set in microdolomite) with curvilinear 

orientation of individual laths. 

5. Laminated dolomite, subsurface. Nodules in laminated dolomite. These nodules probably were originally composed of anhydrite and formed prior to I ithification. They are 

lined with a 1-mm layer of"cherty" silica and later filled with sparry calcite cement. 

The sparry calcite does not completely fill the nodule space, and preservation of good 

crystal terminations on the calcite suggests that the nodule was at one time a void 

subsequently infilled by both silica and calcite. A large stylolite transects the sample. 

The laminations are probably of algal origin (algal mats) and, together with the 

"anhydrite" nodules, a product of sabkha sedimentation. 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 857 PLATE ll 

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5 

BARITE, CELESTITE, MACRODOLOMITE, ANHYDRITE, LAMINATED DOLOMITE 
PLATE 12 

FIGURE 1. Stylolites,69A- 4, 285 feet, x65. Network of bitumen-filled stylolites, each of which 

tends to follow the outlines of the crinoid debris. Dolomite rhombs are concentrated 

along the stylolites. 

2. Stylolite, 68A-4B, +20 feet, x65. Bitumen-filled stylolite in pellet packstone. 

Anhedral dolomite is present within the stylolite but absent from the adjacent host 

rock. 

3. Bioclastic packstone, 69A-1, base of Kayak Shale, x65. Sparry-calcite-filled fracture, F, 

(subvertical) displaced by a later stylolite, S, zone (vertical). The pelecypod clast 

(right) is preserved in sparry calcite with a radial drusy fabric at its margins passing 

into an equant fabric . This fabric almost certainly formed by the infilling of a cast by 

sparry calcite cement. 

4. Fractures, 68A- 4B, + 160 feet, x 33. Parallel hairline fractures filled with sparry 

calcite cement in a bioclastic pellet wackestone. 

5. Bryozoan grainstone, 70A-5, 2,010 feet, x 200. The quartz crystal with well-developed 

prismatic sides and a tendency to pyramidal termination occurs within a bryozoan 

fragment. No detrital core is apparent to this crystal, which is probably authigenic. 

6. Argillaceous wackestone, 70A- 4, 190 feet, x33. Subparallel lamination of the matrix 

tends to be interrupted by larger bioclasts. Probably sheared. 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 857 PLATE 12 

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STYLOLITES, BIOCLASTIC PACKSTONE, FRACTURES, BRYOZOAN GRAINSTONE , ARGILLACEOUS WACKESTONE