Horses in Fensters of the Pulaski Thrust Sheet, Southwestern Virginia: 

Structure, Kinematics, and Implications for Hydrocarbon Potential of the 

Eastern Overthrust Belt

Fluvial Deposition in the Central Appalachians During the Early 

Pennsylvanian

Disturbed Zones: Indicators of Subsurface Faults and Possible Hydrocarbon 

Traps in the Valley and Ridge and Appalachian Plateau Provinces of 

Pennsylvania, Maryland, Virginia, and West Virginia

Reevaluation of Conodont Color Alteration Patterns in Ordovician Rocks, 

East-Central Valley and Ridge and Western Blue Ridge Provinces, Tennessee

U.S. GEOLOGICAL SURVEY BULLETIN 1839-A-D

Horses in Fensters of the Pulaski Thrust Sheet, Southwestern Virginia: 

Structure, Kinematics, and Implications for Hydrocarbon Potential of the 

Eastern Overthrust Belt

By ARTHUR P. SCHULTZ

Fluvial Deposition in the Central Appalachians During the Early 

Pennsylvanian

By CHARLES L. RICE and JOSEPH F. SCHWIETERING

Disturbed Zones: Indicators of Subsurface Faults and Possible Hydrocarbon 

Traps in the Valley and Ridge and Appalachian Plateau Provinces of 

Pennsylvania, Maryland, Virginia, and West Virginia

By HOWARD A. POHN and TERRI L. PURDY

Reevaluation of Conodont Color Alteration Patterns in Ordovician Rocks, 

East-Central Valley and Ridge and Western Blue Ridge Provinces, Tennessee

By RANDALL C. ORNDORFF, ANITA G. HARRIS, and ARTHUR P. SCHULTZ

U.S. GEOLOGICAL SURVEY BULLETIN 1839-A-D 

EVOLUTION OF SEDIMENTARY BASINS-APPALACHIAN BASIN
DEPARTMENT OF THE INTERIOR 

DONALD PAUL MODEL, Secretary

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director

UNITED STATES GOVERNMENT PRINTING OFFICE: 1988

For sale by the Books and Open-File Reports Section, 

U.S. Geological Survey, Federal Center, 

Box 25425, Denver, CO 80225

Library of Congress Cataloging in Publication Data

Schultz, Arthur P.

Evolution of sedimentary basins Appalachian basin.

(U.S. Geological Survey bulletin ; 1839 A-D)

Supt. of Docs. no. : I 19.3:1839A-D

Bibliography: p.

1. Sedimentation and deposition. 2. Geology Appalachian Region. I.

Title. II. Series. 

QE75.B9 no. 1839A-D [QE571] 557.3 s 88-600224 [557.4]
Chapter A

Horses in Fensters of the Pulaski Thrust Sheet, 

Southwestern Virginia: Structure, 

Kinematics, and Implications for Hydrocarbon 

Potential of the Eastern Overthrust Belt

By ARTHUR P. SCHULTZ

A multidisciplinary approach to research studies of sedimentary 

rocks and their constituents and the evolution of sedimentary 

basins, both ancient and modern

U.S. GEOLOGICAL SURVEY BULLETIN 1839 

EVOLUTION OF SEDIMENTARY BASINS-APPALACHIAN BASIN

CONTENTS

Abstract Al

Introduction Al

Geologic setting A3

Horses and fensters A3

Implications for hydrocarbon potential A6

Conclusions A7

References cited A10

FIGURES

1,2. Maps showing:

1. Major thrust faults of southern Appalachian Valley and Ridge province, 

Kentucky, Tennessee, West Virginia, Virginia, and North Carolina Al

2. Major thrust faults of southern Appalachian Valley and Ridge province, 

horses of Pulaski thrust sheet, and distribution of Mississippian rocks 

discussed in report A2

3. Cross section A-A' showing major frontal tectonic ramp of Pulaski thrust 

sheet A2

4. Map showing western edge of Price Mountain fenster, including distribution 

of rooted Mississippian rocks and complexly deformed horses that lie below 

Cambrian rocks of Pulaski thrust sheet and above Mississippian rocks A4

5. Cross section Z-Z' showing structural relationships between Mississippian 

rocks exposed in Price Mountain fenster, horses around edge of fenster, and 

Cambrian rocks of base of Pulaski thrust sheet A5

6. Sketch of outcrop along edge of Price Mountain fenster A5

7. Photomicrographs of undeformed and cataclasized Silurian sandstones A5

8. Cumulative frequency diagram showing grain size of Silurian sandstones in 

horses around Price Mountain fenster A6

9. Photomicrograph of dolomite microbreccia from Ordovician horse A6

10. Histograms showing stages of intracrystalline deformation of Silurian sandstones resulting from increased amounts of cataclastic deformation A6

11. Flinn diagram of lensoid double boudinage showing distribution of strain in 

thinly bedded Ordovician rocks that are horses of Pulaski thrust sheet A7

12. Structural plots for folds in thinly bedded Ordovician rocks in horses of 

Pulaski thrust sheet A7

13. Map showing horses exposed in fensters of Pulaski thrust sheet A8

14. Cross section X-X' showing structural relationships between Devonian and 

Mississippian rocks of rooted footwall, horse duplexes, and Cambrian rocks 

of Pulaski thrust sheet A8

15. Sketch of outcrop section W-W showing overturned, faulted core of antiform composed of Ordovician and Silurian rocks A9

16. Schematic drawings showing simple kinematic model for horse derivation at 

frontal tectonic ramp of thrust sheet A9

Contents III
17, 18.

Maps showing:

17. Location of geochemical samples and coal-bed methane test wells A10

18. Thermal maturation level of rocks in study area based on conodont color 

alteration values A12

TABLE

1. Results of Rock-Eval pyrolysis of potential source rocks of Devonian and 

Ordovican age, Pulaski thrust sheet, southwestern Virginia All

CONVERSION FACTORS FOR SOME SI METRIC AND U.S. UNITS OF MEASURE

To convert from To Multiply by

Feet (ft) Meters (m) 0.3048

Miles (mi) Kilometers (km) 1.609

Pounds (Ib) Kilograms (kg) .4536

Degrees Fahrenheit (°F) Degrees Celsius (°C) Temp °C=(temp °F-32)/l.

IV Contents
EVOLUTION OF SEDIMENTARY BASINS-APPALACHIAN BASIN

Horses in Fensters of the Pulaski Thrust Sheet, 

Southwestern Virginia: Structure, Kinematics, and 

Implications for Hydrocarbon Potential of the Eastern 

Overthrust Belt

By Arthur P. Schultz

Abstract

Highly deformed rocks of Cambrian through Devonian age are exposed in fensters of the Pulaski thrust sheet 

near the northern terminus of the southern Appalachian 

Valley and Ridge province. Detailed mapping of these 

outcrops shows a consistency of structural style namely, 

faulted antiformal synclines having duplex geometry. 

Examination of strain data and cross sections suggests that 

the fensters expose rootless tectonic slices, or horses. 

Structural analysis of the rocks shows that cataclasis was 

the dominant deformation mechanism in thickly bedded 

carbonate rocks and sandstones. By contrast, isoclinal 

folding, cleavage, and boudinage were the dominant 

mechanisms in thinly bedded shales, sandstones, and 

limestones. Both the amount of tectonic thinning and the 

intensity of strain in the horses are dependent on lithotectonic units and the distance of transport from the root 

zone, which is perhaps a frontal tectonic ramp in the 

trailing part of the subjacent Saltville thrust sheet. Seismic 

studies indicate that this ramp is east of and below thrust 

sheets of the Valley and Ridge and western Blue Ridge 

provinces, an interpretation supported by structural studies of rocks in the fensters. Thermal maturation and 

geochemical data suggest that coal-bed methane in rocks 

of Mississippian age may exist below thermally overmature thrust sheets of the eastern Valley and Ridge and 

western Blue Ridge provinces. Rocks of Ordovician and 

Devonian ages in this area may have been source rocks 

but do not contain hydrocarbons.

INTRODUCTION

Regional-scale seismic studies of the Eastern Overthrust Belt have resulted in speculation about this frontier 

hydrocarbon province (Cook and others, 1979; Harris and 

Bayer, 1979; Milici and others, 1979; Harris and others, 

1981, 1982). Hydrocarbon-bearing Paleozoic sedimentary

rocks probably extend from surface exposures in the Valley 

and Ridge province of the Appalachian foreland eastward 

below thrust sheets of metamorphic rocks of the Blue Ridge 

and Piedmont provinces, but the hydrocarbon potential of 

these sedimentary rocks is very poorly known because 

drilling is nonexistent in the area and fensters are few.

This report describes certain complex structures associated with the Pulaski thrust sheet in southwestern Virginia 

(figs. 1, 2). These structures are tectonic slices or horses, 

many of which are exposed in fensters, and they have been 

termed "windows of dislodged slices" or schurflingsfensters 

(Tollman, 1968; Boyer and Elliot, 1982; Schultz and 

Anders, 1985). The tectonic rootless slices of sedimentary 

rocks of Cambrian through Devonian age are interpreted to 

have been derived from below the easternmost exposed 

rocks of the Valley and Ridge province and perhaps from 

below rocks of the Blue Ridge province.

Acknowledgments. The author thanks Donald E. 

Anders of the U.S. Geological Survey (USGS) for geochemical analyses, Anita G. Harris and Randall Orndorff

/ West Virginia

100 KILOMETERS

Figure 1. Major thrust faults of southern Appalachian 

Valley and Ridge province, Kentucky, Tennessee, West 

Virginia, Virginia, and North Carolina. Location of study 

area (fig. 2) also shown.

Manuscript approved for publication, 5/16/88 Horses in Fensters of Pulaski Thrust Sheet, Southwestern Virginia A1
81W 80°00'

37°30' -

37°00' -

APPALACHIAN PLATEAU PROVINCE 

A

\':'-\ Mississippian rocks

EXPLANATION 

^fc Horse Thrust fault

dashed where location uncertain

Figure 2. Major thrust faults of southern Appalachian Valley and Ridge province, horses of 

Pulaski thrust sheet, and distribution of Mississippian rocks discussed in report. Line of section 

A-A' (fig. 3) and locations of areas of figures 4 and 13 also shown. Modified from Bartholomew 

and others (1982).

APPALACHIAN PLATEAU 

PROVINCE

VALLEY AND RIDGE PROVINCE BLUE RIDGE 

PROVINCE

PRICE MOUNTAIN

FENSTER 

Horse I

Middle Cambrian through Mississippian 

rocks on Pulaski frontal ramp

10 KILOMETERS

Horse derived from 

Pulaski frontal ramp

NO VERTICAL EXAGGERATION

	EXPLANATION 

I'--. M ?.| Mississippian rocks 

| PS | Silurian and Devonian rocks

| O | Lower Cambrian Rome Formation through Ordovician rocks

| L | Lower Cambrian rocks

|L /p<3 Precambrian and Lower Cambrian rocks

| p | Precambrian rocks

Thrust fault arrow showing sense of movement; 

dashed where inferred

Figure 3. Cross section A-A' showing major frontal tectonic ramp of Pulaski thrust sheet, the proposed source of horses 

exposed in fensters. Modified from Gresko (1985) and Woodward (1985).

A2 Evolution of Sedimentary Basins Appalachian Basin
(USGS) for unpublished conodont data, and C. Scott 

Southworth (USGS), Robert C. McDowell (USGS), and 

Judith W. Stoeser (MESU Associates) for manuscript 

reviews.

GEOLOGIC SETTING

The Pulaski thrust fault (fig. 1) is one of several 

major, southeast-dipping thrust faults of the central and 

southern Valley and Ridge province and has been traced 

along strike for approximately 500 km (Cooper, 1970; 

Rodgers, 1970) from a terminus in central Virginia southwestward into Tennessee, where it is overridden by rocks of 

the Blue Ridge thrust sheet. Estimates of the displacement 

of the Pulaski thrust near the study area range from 15 

(Cooper, 1970) to 50 km (Bartholomew, 1979). Near 

Pulaski, Va., the preserved thickness of the Pulaski thrust 

sheet is about 1,500 m, and the decollement of the Pulaski 

thrust is within shales and dolomites of the Lower Cambrian 

Rome Formation (fig. 3) and the Middle and Upper Cambrian Elbrook Formation. Rocks of Mississippian age are in 

the footwall of the Pulaski thrust sheet along its leading 

edge, in the Price Mountain fenster, and in the core of the 

Salem synclinorium (fig. 3).

Unique to the Pulaski thrust are thick, broken formations near the base of the thrust sheet (Cooper, 1970; 

Bartholomew and Lowry, 1979; Schultz, 1983), the 

unusual and widespread Max Meadows tectonic breccia 

(Cooper, 1970), and, in an area from near Pulaski to 

Roanoke, Va., a series of fensters and horses (fig. 2) (Butts, 

1933, 1940; Cooper, 1939; Marshall, 1959; Bartholomew 

and Lowry, 1979; Schultz, 1979a, b; Bartholomew, 1981; 

Henika, 1981; Decker and others, 1985). Except for the 

Price Mountain fenster, the fensters expose thin, rootless 

tectonic slices or horses. Horses are also exposed along the 

leading edge of the Pulaski fault. Detailed structural and 

strain analysis (Schultz, 1979a,b, 1981) shows that deformation style and intensity in these horses are in striking 

contrast to those in footwall rocks below the Pulaski thrust 

sheet. Rocks of the horses are some of the most highly 

strained in the Appalachian Valley and Ridge province 

(Schultz, 1979a, b, 1981).

HORSES AND FENSTERS

The Price Mountain fenster (fig. 3) exposes a doubly 

plunging, fault-modified anticline of Mississippian rocks 

below Cambrian rocks of the Pulaski thrust sheet. Drilling 

of this structure (Bartholomew and Lowry, 1979; Stanley 

and Schultz, 1983) (fig. 3) shows a continuous, 3,000-mthick section of rocks ranging from Middle Ordovician to 

Lower Mississippian in age. Stratigraphic thickening in the 

Ordovician and Devonian shales has been attributed to 

minor faulting within these Stratigraphic sections (Harris

and Milici, 1977). Structural interpretations based on seismic data (Gresko, 1985) collected across the Price Mountain anticline place basement rocks at a depth of 7,000 m, a 

depth consistent with projected thicknesses of rocks of Late 

Cambrian through Middle Ordovician age below available 

drill-hole data (Bartholomew and Lowry, 1979). The Price 

Mountain sequence is part of the Saltville thrust sheet 

(Bartholomew and Lowry, 1979; Gresko, 1985) (figs. 2, 3).

Complexly deformed horses ranging in age from Late 

Ordovician to Middle Devonian are located along the 

Pulaski fault between Cambrian rocks of the hanging wall 

and Mississippian rocks of the footwall. Many of these 

horses are exposed along the leading edge of the thrust and 

in fensters in the Pulaski and Roanoke areas (fig. 2). Horses 

along the southwestern edge of the Price Mountain fenster 

are discontinuous, faulted lensoid rock masses having 

duplex geometry (Schultz, 1979a, b) in which folded 

Cambrian rocks of the Pulaski thrust sheet form the roof 

thrust (figs. 4, 5). Irregular fault contacts separate individual horses in the duplexes, and much of the original 

Stratigraphic sequence is missing. Inverted Stratigraphic 

sequences predominate (Schultz, 1979a, b). Mesoscopic 

deformation in the horses increases in intensity with transport distance (Schultz, 1981). The smaller horses consist of 

Ordovician dolomite and Silurian sandstone clasts supported in a matrix of Ordovician and Devonian shales and 

siltstones (fig. 6). The more competent sandstone clasts of 

the fault zone have been internally deformed by a pervasive 

mesoscopic and microscopic brittle fracture or cataclasis, 

such that the original sedimentary fabric of the rock is 

obliterated (fig. 7). Cataclasis of transported sandstone 

clasts resulted in an extremely poorly sorted fabric of 

angular grains that have little to no preferred long-axis 

orientation and reduced mean grain size (Schultz, 1979a, b) 

(fig. 8). Cataclasis in Ordovician dolomite clasts (fig. 9) 

disrupted the original crystalline fabric and produced microbreccias. Intracrystalline deformation of the cataclastic 

rocks is minor and is similar to that of rocks away from the 

fault zone (fig. 10).

Penetrative, tectonically induced, mesoscopic 

melangelike deformation fabrics are in horses consisting of 

thinly bedded, alternating sequences of Ordovician and 

Devonian shales, sandstones, and limestones. These deformation fabrics consist of isolated, fractured, and flattened 

inclusions of more competent rock in a cleaved matrix of 

less competent shale. The melangelike inclusions are lensoid double boudinage and are 1 cm to 3 m long. In all 

cases, the boudin and matrix are of the same Stratigraphic 

formation. Variably oriented extension fractures in the 

boudin suggest that the bedding from which the boudin 

were derived was extended in several directions. This 

conclusion is consistent with strain data (fig. 11), which 

show that tectonic flattening was the dominant deformation 

mechanism during formation of the melangelike fabric in 

the horses. The sequence in fabric development consists of

Horses in Fensters of Pulaski Thrust Sheet, Southwestern Virginia A3
80°30'

	EXPLANATION 

I M I Mississippian rocks 

I D | Devonian rocks 

I S I Silurian rocks 

I UP | Upper Ordovician rocks 

| MO | Middle Ordovician rocks 

I LO I Lower Ordovician rocks

|::':.y.'-.1 Middle Cambrian rocks of 

Pulaski thrust sheet

^ Pulaski roof thrust, sawteeth on

 upper plate

A Pulaski floor thrust, sawteeth on

upper plate 

Faulted horse contact, hachures

on upper block

Thrust fault sawteeth on 

upper plate

Location of outcrop ' .'. '.' ;' ': section V" ---" 

A- PULASKI : ; ; v:

 THRUST :;; : 

Strike and dip of beds '.:'££&: :$.'-vr ^iV^-'-^'X-JI 

Strike and dip of overturned beds '-^:- ://-:.V- :^V:A':^V-:'{:V-:.: :V':Vji>

37°10'

^PULASKI THRUST SHEET %£&£*

Figure 4. Western edge of Price Mountain fenster, including distribution of rooted Mississippian 

rocks and complexly deformed horses that lie below Cambrian rocks of Pulaski thrust sheet and 

above Mississippian rocks. Line of section Z-Z' (fig. 5) and location of outcrop section Y-Y' (solid 

circle) (fig. 6) also shown.

rotation (fig. 12), followed by transposition of early isoclinally folded rocks and formation of penetrative cleavage 

(Schultz, 1981). The southeasternmost fensters of the 

Pulaski thrust sheet in the Price Mountain area (fig. 3) 

expose rocks of similar structural complexity characterized 

by rootless and fault-bounded, stratigraphically attenuated 

slices (figs. 13, 14). In this area, lithologic variations are 

minimal, and the individual slices that compose the horses 

are more internally coherent; that is, mesoscopic deformation is limited to mesoscopic brittle faults (fig. 15).

Cross sections (figs. 3, 5, 14) drawn on the basis of 

existing drill-hole data and thickness constraints and available seismic interpretations (Stanley and Schultz, 1983; 

Gresko, 1985) suggest that rocks of Middle Cambrian

through Devonian age in fensters in the study area lie 

structurally above a footwall of rocks of Mississippian age. 

This footwall may be continuous in the subsurface with 

southeast-dipping rocks on the southeastern limb of the 

Price Mountain anticline (figs. 3, 5). Interpretations of all 

other fensters of the Pulaski thrust sheet (Cooper, 1939; 

Marshall, 1959; Bartholomew, 1981;Henika, 1981; Decker 

and others, 1985) (fig. 2) are similar to those described near 

Pulaski (Schultz, 1979a, b). In all cases, highly deformed, 

rootless slices of stratigraphically older rocks are thought to 

lie above relatively less deformed younger footwalls.

A simple kinematic model for the origin and emplacement of horses (fig. 16) involves the interaction of an 

overriding thrust sheet with a subthrust syncline on or near a

A4 Evolution of Sedimentary Basins Appalachian Basin
PRICE MOUNTAIN FENSTER

Horse duplex in schurflingsfenster

PULASKI ROOF THRUST

SW

^PULASKI FLOOR THRUST

Mississippian rock

EXPLANATION 

p | Devonian rocks

| S | Silurian rocks

| UQ | Upper Ordovician rocks

I MO | Middle Ordovidan rocks

fr.':':':'-] Middle Cambrian rocks of 

Pulaski thrust sheet

' T- ^ Bedding surface showing 

facing direction

NO VERTICAL EXAGGERATION

Thrust fault, arrow showing 

sense of movement; 

dashed where inferred

Figure 5. Cross section Z-Z' showing structural relationships between Mississippian rocks exposed in Price Mountain 

fenster, horses around edge of fenster, and Cambrian rocks of base of Pulaski thrust sheet. Horses below ground surface 

shown schematically.

H-

 Horse duplex

NE PRICE

Y MOUNTAIN

-| FENSTER /PULASKI FLOOR 

N. / THRUST

PULASKI ROOF THRUST

EXPLANATION

Mississippian rocks Cj~ I Upper Ordovician rocks. showing cleavage 

tHZ-EJrr] Devonian rocks [^J=J Lower Ordovician rocks 

|-' ' ' I Silurian rocks l^yy'-! Cambrian rocks

_ *- _ Thrust fault, arrow showing sense of movement; 

dashed where inferred

0 10 METERS 

NO VERTICAL EXAGGERATION

Figure 6. Outcrop along edge of Price Mountain fenster (line of section Y-Y', fig. 4) showing relatively small horse 

duplex between Mississippian rocks of Price Mountain fenster and Cambrian rocks of Pulaski sheet. Rocks in duplex have 

undergone substantial amount of tectonic mixing and deformation during transport from their root zone. Drawn from 

photograph presented by Schultz (1979a).

Figure 7. Photomicrographs of Silurian sandstones. A, Quartzite believed to be similar to undeformed protolith of 

cataclasites in horses of Pulaski thrust sheet. Sample collected on Saltville thrust sheet (fig. 2), about 10 km northwest of 

outcrop sketched in figure 6. B, Well-developed cataclastic fabric in Silurian sandstone from a horse of Pulaski thrust 

sheet. Development of poorly sorted fabric and angular grains indicates complete disruption of original sedimentary 

fabric. Sample collected at outcrop location Y-Y' (figs. 4, 6).

Horses in Fensters of Pulaski Thrust Sheet, Southwestern Virginia A5
99r

95 Z

HI

U 

CC 85

UJ

°- 70 

UJ

p

6 12 25 50 100 200 

GRAIN SIZE, IN MICRONS

400

Figure 8. Cumulative frequency diagram showing grain 

size of Silurian sandstones in horses around Price Mountain fenster. Each curve based on 300 measurements of 

longest diameter of grains observed in thin section. 

Curves A, B, and C are based on counts from three 

mutually perpendicular thin sections of the same cataclastically deformed sandstone and indicate little or no 

preferred orientation of grains, an expected result of 

cataclasis. Curve 1 for undeformed sandstone shown in 

figure 7A. Method from Engelder (1974)

tectonic frontal ramp. The first stage of horse development 

is footwall imbrication in a subthrust synclinal hinge and 

(or) in either the overturned limb or the normal limb of the 

syncline. The location of footwall thrusts determines the 

eventual facing of the horses. Detachment of the pieces 

(horse) from the footwall and their transport up the frontal 

ramp onto a decollement complete the early stages of horse 

development. Subsequent transport of the horses along the 

upper level decollement intensifies internal deformation 

fabrics and thins and tectonically mixes stratigraphic units.

10CH

UNDULOSE 

EXTINCTION

A B

STRAIN RECOVERY 

RECRYSTALLIZED GRAINS 

35-,

30-

25-

20-

10-

DEFORMATION BANDS 

AND (OR) LAMELLAE

z 10-

5-

\\\Y \\\Y

\\\\ 

\\\\ 

\\\\

\\\\

SILURIAN SANDSTONES

A Undeformed rocks northwest of thrust belt 

B Protocataclasites of the Pulaski decollement 

C Cataclasites of the Pulaski decollement 

D Ultracataclasites of the Pulaski decollement

E jjj

Figure 10. Histograms showing stages of intracrystalline 

deformation of Silurian sandstones resulting from 

increased amounts of cataclastic deformation. Percentage 

of detrital grains showing deformation is used as measure 

of deformation; 300 grains observed in each group of 

sandstones. Histograms show that no appreciable change 

occurred in amount of intracrystalline deformation as 

cataclasis intensified. Classification of stages of deformation from Sibson (1977).

Figure 9. Photomicrograph of dolomite microbreccia 

from Ordovician horse. Angular fragments of dolomite 

have been plucked from the original crystalline fabric 

along cataclastic shears. Collected at outcrop location 

Y-Y' (figs. 4, 6).

IMPLICATIONS FOR HYDROCARBON 

POTENTIAL

The kinematic model for the evolution of horses in 

fensters of the Pulaski thrust sheet has important implications for hydrocarbon potential. If rocks of Devonian and 

(or) Mississippian age are below rocks in the fensters, they 

may also extend below the easternmost exposed Pulaski and 

Max Meadows thrust sheets of the Valley and Ridge 

province and perhaps below the westernmost part of the 

Blue Ridge province (fig. 3). This interpretation agrees well 

with regional seismic interpretations near this area that 

postulate undeformed foreland Paleozoic sedimentary rocks 

to the east of and below Precambrian metamorphic rocks of 

the Blue Ridge province (Milici and others, 1979; Harris 

and others, 1982).

In the study area, coals of Mississippian age below 

the Pulaski thrust sheet have proven coal-bed methane

A6 Evolution of Sedimentary Basins Appalachian Basin
k=x UNIAXIAL CIGARS

1+e, 

1+e3

k=- b-1

 1<ks» 

CONSTRICTED 

 ELLIPSOIDS

1>k>0 FLATTENED ELLIPSOIDS

_l k=0 UNIAXIAL 

4 PANCAKES

 =b (n = 100)

Figure 11. Flinn diagram of lensoid double boudinage 

showing distribution of strain in thinly bedded Ordovician 

rocks that are horses of Pulaski thrust sheet in area of 

study. Seventy-three percent of boudin fall within flattened ellipsoid field of diagram, e-,, e2 , and e3/ axes of 

principal extensions; a, ratio of elongations in e-, and e2 

directions; b, ratio of elongations in e2 and e3 directions; 

k, slope of line defining strain types. Method from Cowan 

(1978).

potential (Stanley and Schultz, 1983). If rootless horses in 

the fensters southeast of the Price Mountain fenster overlie 

Mississippian rocks in the footwall. as the model presented 

herein suggests, then the area of coal-bed methane potential 

can be increased and may extend below the metamorphic 

rocks of the Blue Ridge province (fig. 3).

Results of Rock-Eval pyrolysis (fig. 17, table 1) of 

samples from Ordovician and Devonian horses of the 

Pulaski thrust sheet suggest that these rocks may have been 

potential source rocks of hydrocarbons. For a rock to be 

considered a potential source rock, the total organic carbon 

value must exceed 0.5 to 1.0 percent carbon (Tissot and 

Welte, 1984); 10 of the samples tested contain enough 

carbon to qualify. Hydrocarbon-generating capacity (or 

genetic potential) is expressed as the total hydrocarbon 

content (HC = SI + S2) (table 1), and rocks containing 

more than 6 mg HC per gram of rock are considered to have 

good resource potential (Tissot and Welte, 1984). None of 

the samples analyzed, however, had a total hydrocarbon 

content above this value. Thermal maturation of the rocks, 

as measured by conodont color alteration index (CAI), is 

slightly higher (CAI 4) (fig. 18) than that of Mississippian 

coals in the Price Mountain fenster (CAI 3.5) (fig. 18) but 

is well within the upper limits of the dry gas window (Tissot 

and Welte, 1984). If coal-bearing Mississippian rocks 

extend to the east below thermally overmature thrust sheets 

(fig. 3), a viable coal-bed methane potential may exist 

below these rocks.

DIP OF AXIAL SURFACE, IN DEGREES 

.90 80 60 _____30_____10

Figure 12. Structural plots for folds in thinly bedded 

Ordovician rocks in horses of Pulaski thrust sheet. A, 

Schmidt equal-area stereographic plot of pole to axial 

surface (solid circles) and fold axes (solid squares) in thinly 

bedded Ordovician rocks in horses of Pulaski thrust sheet. 

Variability of orientation reflects rotation of folds during 

formation of melangelike deformation fabric. Number of 

observations n=34. B, Fleuty diagram for folds in A shows 

that a wide range of fold styles is characteristic of 

melangelike deformation in horses. Method after Fleuty 

(1964).

CONCLUSIONS

Fensters of the Pulaski thrust sheet in southwestern 

Virginia expose both rooted and rootless rocks. A simple 

kinematic model for the formation of horses in these 

fensters involves detachment and transport of thrust slices 

from footwall subthrust synclines. These subthrust synclines developed in a footwall composed of rocks of

Horses in Fensters of Pulaski Thrust Sheet, Southwestern Virginia A7
37°05' -

EXPLANATION 

Devonian rocks 

Silurian rocks 

Upper Ordivician rocks 

Middle Ordovician rocks 

Lower Ordovician rocks 

Upper Cambrian rocks

Middle Cambrian rocks of

Pulaski thrust sheet 

Pulaski fault, sawteeth on

upper plate 

Fault between horses.

hachures on upper block 

Strike and dip of bedding 

Strike and dip of overturned

bedding

Syncline 

Anticline 

Antiform showing plunge

Figure 13. Horses exposed in fensters of Pulaski thrust sheet. Note juxtaposition of horses within each duplex along 

thrust faults contained within fensters. Location of map shown in figure 2; lines of section X-X' (fig. 14) and VV-VV' (fig. 

15) also shown.

PULASKI ROOF THRUST

	EXPLANATION

| M | Mississippian rocks £

I D | Devonian rocks

| S | Silurian rocks

| UP | Upper Ordovician rocks

| MO | Middle Ordovician rocks

| LO | Lower Ordovician rocks

| U | Upper Cambrian rocks

|MCj Middle Cambrian rock

0 1 KILOMETER 

NO VERTICAL EXAGGERATION fn^T] Middle Cambrian rocks of 

k* Pulaski thrust sheet

 - !_ Bedding surface showing 

facing direction

__^. Thrust fault arrow showing sense of movement; 

dashed where inferred

 Contact

Figure 14. Cross section X-X' showing structural relationships 

between Devonian and Mississippian rocks of rooted footwall, horse 

duplexes, and Cambrian rocks of Pulaski thrust sheet. Line of section 

shown on figure 13.

A8 Evolution of Sedimentary Basins Appalachian Basin
NW SE 

IV'

25 METERS

NO VERTICAL EXAGGERATION

Road level

[ | Middle Silurian rocks

|-i:.';./V;| Lower Silurian rocks

r^d Upper Ordovician rocks

^^ Fault, arrow shows 

**^ relative movement

Figure 15. Sketch of outcrop section VV-VV showing overturned, faulted core of antiform composed of 

Ordovician and Silurian rocks. Antiform is part of larger horse complex shown in figures 13 and 14. Line 

of section shown in figure 13.

W

Flattening, stretching, and tectonic thinning 

of horse during transport along decollement

Present-day erosion 

surface

STAGE THREE

Detachment and transport of horse 

off ramp and onto decollement; 

anticlinal folding of overriding sheet

STAGE TWO

Footwall imbrication on the 

frontal thrust ramp in 

core of subthrust syncline

STAGE ONE 

Figure 16. Simple kinematic model for horse derivation at frontal tectonic ramp of thrust sheet.

Horses in Fensters of Pulaski Thrust Sheet, Southwestern Virginia A9
37°30'

37°00'

STOP'_____________ 

I

APPALACHIAN PLATEAU 

PROVINCE

SOW

c > VALLEY

AND 

'"' RIDGE

.' PROVINCE

West Virginia

20 KILOMETERS 

I

EXPLANATION

0 Geochemical sample locality; nunr her refers to table 1.

Circled number indicates sample has source-rock potential 

- t Thrust fault; dashed where location uncertain

^B Horse

[' .V'.'.'^l Mississippian rocks

Figure 17. Location of geochemical samples and coal-bed methane test wells (Stanley and Schultz, 

1983). Geochemical data for samples shown in table 1.

Cambrian through Mississippian age on the frontal tectonic 

ramp of the Pulaski thrust. This frontal ramp may extend 

eastward below the Blue Ridge province. This interpretation agrees well with regional-scale models for the evolution of the Eastern Overthrust Belt derived from seismic 

studies. Studies of the thermal maturity of horses in fensters 

in the Pulaski thrust sheet seem to indicate that rocks of 

similar age below thrust sheets of the Valley and Ridge and 

Blue Ridge provinces probably are in the upper part of the 

dry gas window. In addition, methane in Mississippian 

coals extending into this frontier hydrocarbon province may 

have an economic potential. Hydrocarbons probably are not 

in Ordovician and Devonian source rocks but may be 

elsewhere in this structurally complex area and may have 

been derived from the Ordovician and Devonian black 

shales.

REFERENCES CITED

Bartholomew, M.J., 1979, Thrusting component of shortening 

and a model for thrust fault development at the central 

southern Appalachian junction [abs.]: Geological Society of 

America Abstracts with Programs, v. 11, p. 384-385.

 1981, Geology of the Roanoke and Stewartsville quadrangles, Va.: Virginia Division of Mineral Resources Publication 34, 23 p.

Bartholomew, M.J., and Lowry, W.D., 1979, Geology of the 

Blacksburg quadrangle, Va.: Virginia Division of Mineral 

Resources Publication 14, 1 sheet, scale 1:24,000.

Bartholomew, M.J., Schultz, A.P., Henika, W.S., and Gathright, 

T.M., II, 1982, Geology of the Blue Ridge and Valley and 

Ridge at the junction of the central and southern Appalachians, in Lyttle, P.T., ed., Central Appalachian geology: 

Falls Church, Va., American Geological Institute, p. 

121-170.

Boyer, S.E., and Elliott, D., 1982, Thrust systems: American 

Association of Petroleum Geologists Bulletin, v. 66, no. 9, p. 

1196-1230.

Butts, C., 1933, Geologic map of the Appalachian Valley of 

Virginia: Virginia Geological Survey Bulletin 42, 56 p.

 1940, Geology of the Appalachian Valley in Virginia, pt. 

I: Virginia Geological Survey Bulletin 52, 568 p.

Campbell, M.R., 1925, The Valley coal fields of Virginia: 

Virginia Geological Survey Bulletin 25, 300 p.

Cook, F.A., Albaugh, D.S., Brown, L.D., Oliver, I.E., and 

Hatcher, R.D., Jr., 1979, Thin-skinned tectonics in the 

crystalline southern Appalachians; COCORP seismicreflection profiling of the Blue Ridge and Piedmont: Geology, v. 7, no. 12, p. 563-567.

Cooper, B.N., 1939, Geology of the Draper Mountain area, Va.: 

Virginia Geological Survey Bulletin 55, 98 p.

A10 Evolution of Sedimentary Basins Appalachian Basin
Table 1. Results of Rock-Eval pyrolysis of potential source rocks of 

Devonian and Ordovician age, Pulaski thrust sheet, southwestern 

Virginia

Total organic Free hydrocarbons Pyrolyzed

Sample carbon S1 1 hydrocarbons S22

number (in percent) (mg/g of rock) (mg/g of rock)

Devonian black shales

6................ 2.59 0.01

14............... 1.37 .01

17............... 2.12 .02

18............... 2.59 .01

24............... 1.01 0 ___

Ordovican black and gray shales

2................ 0.22 0

3................ .18 0

4A .............. .15 .01

4B .............. .23 0

5................ .26 0

7................ .13 0

11............... 1.27 .02

13A ............. .31 .01

13B ............. .11 0

15............... .26 0

19A ............. .38 .02

19B ............. .24 .03

20A ............. .78 .Ql

20B ............. .43 .02

20C ............. .06 .01

21A ............. .70 .02

21B ............. 1.04 .03

22A ............. .68 .04

22B ............. .36 .02

23............... .14 .01

0.16 

.05 

.07 

.03 

.02

.02

.03

0

.04 

.02

) 

.02

)

.01 

.02 

.11 

.04 

.12

SI, Quantity of organic matter existing in rock as free or adsorbed hydrocarbons.

S2, Quantity of hydrocarbons.

 1970, The Max Meadows breccias; a reply, in Fisher, 

G.W., and others, eds., Studies of Appalachian geology, 

central and southern: New York, Wiley-Interscience, p. 

179-191.

Cowan, D.S., 1978, Origin of blueschist-bearing chaotic rocks in 

the Franciscan Complex, San Simeon, Calif.: Geological 

Society of America Bulletin, v. 89, no. 9, p. 1415-1423.

Decker, E.W., Campbell, K.D., Waller, E.B., Orndorff, R.C., 

and Venkatakrishnan, R., 1985, Structures between thrust 

sheets, Glade Creek Window, Va. [abs.]: Geological Society 

of America Abstracts with Program, v. 17, no. 2, p. 87.

Engelder, J.T., 1974, Cataclasis and the generation of fault gouge: 

Geological Society of America Bulletin, v. 85, no. 10, p. 

1515-1522.

Epstein, A.G., Epstein, J.B., and Harris, L.D., 1977, Conodont 

color alteration; an index to organic metamorphism: U.S. 

Geological Survey Professional Paper 995, 27 p.

Fleuty, M.J., 1964, The description of folds: Geological Association Proceedings, v. 75, p. 461-492.

Gresko, M.J., 1985, Analysis and interpretation of compressional 

(P-wave) and shear (5/f-wave) reflection seismic and geologic data over the Bane dome, Giles County, Va.: Blacksburg, Va., Virginia Polytechnic Institute, unpublished 

M.Sci. thesis, 74 p.

Harris, L.D., and Bayer, K.C., 1979, Sequential development of 

the Appalachian orogen above a master decollement; a 

hypothesis: Geology, v. 7, no. 12, p. 568-572.

Harris, L.D., and Milici, R.C., 1977, Characteristics of thinskinned style of deformation in the southern Appalachians, 

and potential hydrocarbon traps: U.S. Geological Survey 

Professional Paper 1018, 40 p.

Harris, L.D., Harris, A.G., deWitt, W., Jr., and Bayer, K.C., 

1981, Evaluation of southern Eastern Overthrust Belt beneath 

Blue Ridge-Piedmont thrust: American Association of Petroleum Geologists Bulletin, v. 65, no. 12, p. 2497-2505.

Harris, L.D., deWitt, W., Jr. and Bayer, K.C., 1982, Interpretive 

seismic profile along Interstate 1-64 from the Valley and 

Ridge to the coastal plain in central Virginia: United States 

Geological Survey Oil and Gas Investigations Chart OC-123, 

1 sheet.

Henika, W.S., 1981, Geology of the Villamont and Montvale 

quadrangles, Va.: Virginia Division of Mineral Resources 

Publication 35, 18 p.

A11
37°30'

37°00'

81°00'___________ 

I

APPALACHIAN PLATEAU 

PROVINCE

West Virginia

SOW

VALLEY 

AND 

RIDGE 

PROVINCE

20 KILOMETERS 

1

Regional conodont color alteration values

2-3 Hill 4-5

3-4 fr^TJ 5 + 

3.5

EXPLANATION

 4.0 Conondont index locality and color alteration value

 SA Semianthracite Mississippian coal

 SA (M) Coal-bed methane test well

._ Thrust fault; dashed where location uncertain 

Mississippian rocks 

Horse

Figure 18. Thermal maturation level of rocks in study area based on conodont color alteration values 

of Epstein and others (1977) and A.G. Harris (unpublished data, 1985). Semianthracite coal localities 

from Stanley and Schultz (1983), Simon and Englund (1983), and Campbell (1925).

Marshall, F.C., 1959, Geology of the Kent window, Wythe 

County, Va.: Blacksburg, Va., Virginia Polytechnic Institute 

and State University, unpublished M.Sci. thesis, 21 p.

Milici, R.C., Harris, L.D., and Statler, A.T., 1979, An interpretation of seismic cross sections in the Valley and Ridge of 

eastern Tennessee: Tennessee Division of Geology Oil and 

Gas Chart 6, 2 sheets.

Rodgers, J., 1970, The Pulaski fault, and the extent of Cambrian 

evaporites in the central and southern Appalachians, in 

Fisher, G.W. and others, eds., Studies of Appalachian 

geology, central and southern: New York, 

Wiley-Interscience, p. 175-178.

Schultz, A.P., 1979a, Deformation associated with Pulaski overthrusting in the Price Mountain and East Radford windows, 

Montgomery Co., southwest Va.: Blacksburg, Va., Virginia 

Polytechnic Institute and State University, unpublished 

M.Sci. thesis, 134 p.

 1979b, Fault breccia, fault chaos, tectonic melange and 

deformed parautochthonous rocks in the Price Mountain and 

East Radford windows of the Pulaski overthrust, Montgomery County, southwestern Va.: Geological Society of America Southeastern Section Meeting, 1979, Blacksburg, Va., 

Guides to Field Trips 1-3, p. 112-133.

 1981, Progressive development of melange fabrics in 

allochthons of the Pulaski thrust, southwest Va. [abs.]: 

Geological Society of America Abstracts with Program, v, 

13, no. 7, p. 28.

 1983, Broken-formations of the Pulaski thrust sheet near

Pulaski, Va.: Blacksburg, Va., Virginia Polytechnic Institute 

and State University, unpublished Ph.D. thesis, 111 p.

Schultz, A.P., and Anders, D.E., 1985, Schurflingsfensters in the 

Pulaski thrust sheet and their implications for hydrocarbon 

potential [abs.]: American Association of Petroleum Geologists Bulletin, v. 69, no. 9, p. 1447.

Sibson, R.H., 1977, Fault rocks and fault mechanisms: Journal of 

the Geological Society of London, v. 133, pt. 3, p. 191-213.

Simon, P.O., and Englund, K.J., 1983, Test drilling for coal in 

1982-1983 in the Jefferson National Forest, Va., pt. 4, 

Analyses of coal cores from the Valley coal fields: U.S. 

Geological Survey Open-File Report 83-626, 16 p.

Stanley, C.B., and Schultz, A.P., 1983, Coal-bed methane 

resource evaluation, Montgomery County, Va.: Virginia 

Division of Mineral Resources Publication 46, 59 p.

Tissot, B.P., and Welte, D.H., 1984, Petroleum formation and 

occurrence (2d ed.): New York, Springer-Verlag, 699 p.

A12 Evolution of Sedimentary Basins Appalachian Basin
Tollmann, A., 1968, Die Grundbegriffe der deckentektonischen Woodward, N.B., 1985, Valley and Ridge thrust belt; balanced 

Nomenklatur [Basic principles of tectonic thrusting nomen- structural sections, Pennsylvania to Alabama: University of 

clature]: Geotektonische Forschungen, v. 29, p. 26-59. Tennessee Department of Geological Sciences Studies in

Geology 12, 64 p.

References Cited A13

Chapter B

Fluvial Deposition in the Central Appalachians 

During the Early Pennsylvanian

By CHARLES L. RICE and JOSEPH F. SCHWIETERING

A multidisciplinary approach to research studies of sedimentary 

rocks and their constituents and the evolution of sedimentary 

basins, both ancient and modern

U.S. GEOLOGICAL SURVEY BULLETIN 1839 

EVOLUTION OF SEDIMENTARY BASINS-APPALACHIAN BASIN

CONTENTS

Abstract Bl

Introduction Bl

Geologic setting Bl

Sediment dispersal patterns for the Pennsylvanian B3

Drainage systems B3

Depositional models B5

Conclusions B8

References cited B8

FIGURES

1. Paleogeographic map showing distribution of Upper Mississippian rocks and 

inferred Late Mississippian-Early Pennsylvanian drainage system, Kentucky, 

Ohio, West Virginia, and parts of adjacent States B2

2. Correlation chart for Lower and Middle Pennsylvanian and Upper Mississippian stratigraphic units used in report B3 

3, 4. Photographs showing:

3. Crossbedded sets of Pennsylvanian quartz-pebble conglomerate and pebbly quartz arenite on Pilot Knob, Levee Wi-minute quadrangle, eastcentral Kentucky B3

4. Detail of Pennsylvanian crossbedded quartz-pebble conglomerate on Pilot 

Knob, Levee VVi-minute quadrangle, east-central Kentucky B4

5. Isopach map of Mississippian Greenbrier Limestone in West Virginia showing traces and directions of flow of inferred paleochannels B4

6. Geologic sections showing westward onlap and pinchout of Pennsylvanian 

Lee Formation in eastern Kentucky B5

7. Schematic drawing showing two interpretations of Early Pennsylvanian 

paleogeography in the Appalachian basin B6

8. Photograph showing southeast-inclined tabular sets of crossbedded pebbly 

quartz arenite of basal part of Lee Formation, eastern Kentucky B7

CONVERSION FACTORS FOR SOME SI METRIC AND U.S. UNITS OF MEASURE

To convert from To Multiply by

Feet (ft) Meters (m) 0.3048

Miles (mi) Kilometers (km) 1.609

Pounds (Ib) Kilograms (kg) .4536

Degrees Fahrenheit (°F) Degrees Celsius (°C) Temp °C=(temp °F-32)/l.

Contents III

EVOLUTION OF SEDIMENTARY BASINS-APPALACHIAN BASIN

Fluvial Deposition in the Central Appalachians During the 

Early Pennsylvanian

By Charles L. Rice1 and Joseph F. Schwietering2

Abstract

Development of a Pennsylvanian fluvial system in 

eastern North America following emergence of the craton 

in Late Mississippian time was controlled by a southwestdipping paleoslope. Tectonism during the Late Mississippian and Early Pennsylvanian caused streams draining the 

Cincinnati arch toward the southwest to be captured and 

diverted to the south and southeast into the subsiding 

Appalachian basin. These drainage modifications resulted 

in a significant contribution of sediment to the Appalachian basin from source areas to the north and northwest.

INTRODUCTION

Arguments about the existence of a MississippianPennsylvanian unconformity in individual outcrops or small 

areas in the central Appalachian basin have tended to 

overshadow accumulated data that indicate the existence of 

a well-developed fluvial drainage system in much of the 

area by latest Mississippian and earliest Pennsylvanian 

time. Numerous geologic reports, some of which date from 

the early part of the 20th century, describe the basal 

Pennsylvanian channels and rocks that crop out mostly 

along the northwestern border of the Appalachian basin. 

Although the varied nature of the MississippianPennsylvanian contact and the lack of reliable data have 

generally precluded definitive subsurface interpretations for 

much of the Appalachian basin, a few local and regional 

subsurface studies of Carboniferous strata also support a 

fluvial interpretation for the basal Pennsylvanian. This 

report discusses these data and suggests a model of fluvial 

deposition for the Early Pennsylvanian of the Appalachian 

basin that is regionally consistent with that for the related 

Eastern Interior (Illinois) basin to the west.

Concepts of the shape and history of the Appalachian 

basin and of the character of deposition during PennsylvaU.S. Geological Survey, Reston, VA 22092. 

2 West Virginia Geological and Economic Survey, Morgantown, 

WV 26507.

nian time are influenced by a widely held perception that a 

sea existed northwest of the Appalachian orogenic belt and 

its northwest-facing deltas (Englund, 1974). Thick 

sequences of quartz arenites in the Lower Pennsylvanian of 

the Appalachian basin commonly are cited as evidence of 

that sea and of beach or barrier-bar deposition. We propose, 

however, that the quartz arenites, which commonly occur in 

channel deposits, are fluviatile. We also suggest that their 

distribution reveals a drainage pattern showing a significant 

contribution of sediment to the Appalachian basin during 

Early Pennsylvanian time, first from the northern flank of 

the basin and later, by means of stream capture, from 

cratonic sources north and northwest of the basin.

GEOLOGIC SETTING

Late Mississippian deposition in the Appalachian and 

Eastern Interior basins began with formation of shallowwater shelf carbonates (Greenbrier Limestone and equivalent strata), which, in northern Kentucky and adjacent 

areas, contain numerous exposure features and diastems 

indicative of frequent subaerial exposure (Rice and others, 

1979). Predominantly terrigenous strata (Mauch Chunk 

Group and equivalents) subsequently were deposited by 

south- and west-prograding deltas. Subsidence in the Appalachian basin during Late Mississippian time resulted in 

deposition of a wedge of sediments that thickens southeastward and is as thick as 5,000 ft in southeastern West 

Virginia (Arkle, 1974). Thickness projections of Upper 

Mississippian rocks suggest, however, that the Cincinnati 

arch was emergent during the Late Mississippian in most of 

western Ohio, north-central Kentucky, and eastern Indiana 

(Pryor and Sable, 1974).

During Late Mississippian or Early Pennsylvanian 

time, a eustatic lowering of sea level resulted in the 

emergence of most, if not all, of the craton in eastern North 

America. The sea retreated from the craton toward the 

southwest (Swann, 1964), and southwest-flowing rivers cut 

valleys as deep as 450 ft in both the Eastern Interior basin 

(Siever, 1951) and the Appalachian basin (Mrakovich,

Manuscript approved for publication, 5/16/88 Fluvial Deposition in Central Appalachians during Early Pennsylvanian B1
86'

 I 

EXPLANATION

Mauch Chunk Group (Upper 

Mississippian) and equivalent 

strata

Greenbrier Limestone (Upper 

Mississippian) and equivalent 

strata

I I

Area of karst topography

Edge of structural platform

Northwestern margin of J 

depocenter

Escarpment

Older rocks (includes minor Upper 

Mississippian strata in area of 

folded Appalachians)

JESSAMINE 

DOME

38'

Figure 1. Distribution of Upper Mississippian rocks and inferred Late Mississippian-Early Pennsylvanian drainage 

system, Kentucky, Ohio, West Virginia, and parts of adjacent States. Locations of areas A and B depicted in figure 7 also 

shown.

1969). Erosion truncated progressively older strata northward, so that Pennsylvanian rocks directly overlie Ordovician strata in northern Illinois and Devonian strata in New 

York. Upwarping of the Cincinnati arch and erosion of less 

competent shales and siltstones above and below the more 

competent Mississippian carbonate rocks (Greenbrier Limestone and its equivalents) resulted in the formation of a low 

north-facing escarpment that defined the open shape of the 

south-plunging arch and, in particular, the northwestern 

edge of the Appalachian basin (fig. 1). Remnants of that 

escarpment are buried beneath Pennsylvanian rocks in 

southwestern Pennsylvania and southeastern Ohio (Wanless, 1975). The escarpment locally has been exhumed by 

erosion and is represented today, in part, by the Cumberland Escarpment and by Muldraughs Hill (a northeastfacing escarpment) in central Kentucky (Lobeck, 1929) and 

its extension in Indiana.

Emergence of the craton and upwarping of the Cincinnati arch during Late Mississippian and Early Pennsylvanian time were accompanied by relative downwarping of 

the Appalachian basin. Although Rice (1985) has suggested 

that an unconformity between Mississippian and Pennsylvanian strata extends throughout the central Appalachian 

basin, subsidence and sedimentation apparently continued 

in southeasternmost West Virginia and adjoining parts of 

Virginia, areas in which Englund (1974, 1979) reported that 

strata of the Pocahontas Formation (basal Pennsylvanian) 

(fig. 2) conformably overlie Mississippian strata.

B2 Evolution of Sedimentary Basins Appalachian Basin
OHIO

NORTHEASTERN

and

SOUTH-CENTRAL 

KENTUCKY

SOUTHEASTERN 

KENTUCKY

Livingston 

Conglomerate: 

Mbr. of Lee Fm

Mauch

Chunk Group 

and equivalent strata

Greenbrier Limestone and equivalent stratc

SOUTHEASTERN 

WEST VIRGINIA

and 

VIRGINIA

Figure 2. Lower and Middle Pennsylvanian and Upper 

Mississippian stratigraphic units used in report. Pattern 

indicates missing strata; M, horizon containing restricted 

marine fauna; B, horizon containing brackish-water fauna. 

Data from Arkle (1974), Englund (1974), Rice (1984), and 

Wanless (1975).

Figure 3. Crossbedded sets of Pennsylvanian quartzpebble conglomerate and pebbly quartz arenite on Pilot 

Knob, Levee 7 1/2-minute quadrangle, east-central Kentucky. These deposits and those of adjacent Rotten Point 

are west of carbonate escarpment shown in figure 1 and 

comprise a channel fill as thick as 165 ft that rests on Lower 

Mississippian rocks (McDowell, 1978). Current direction is 

southwest. Location of Pilot Knob shown in figure 6. 

Brunton compass shown for scale.

SEDIMENT DISPERSAL PATTERNS FOR THE

PENNSYLVANIAN

In a detailed analysis of the paleogeography of 

Pennsylvanian rocks in the Appalachian basin in Pennsylvania and adjacent States, Meckel (1967) identified two 

distinct source areas for detritus in the Appalachian basin: 

(1) a "tectonic" source area along the southeastern margin 

of the basin in an area of rapid uplift and erosion and (2) a 

stable "cratonic" source area in southern Canada and 

northern New York. Detritus from the tectonic source is 

characterized by sedimentary and metamorphic rock fragments and generally angular to subrounded polycrystalline 

quartz grains, whereas detritus from the cratonic source is 

composed predominantly of well-rounded monocrystalline 

quartz grains, best typified by the quartz arenite of the 

Sharon (conglomerate) Member of the Pottsville Formation 

(fig. 2). Meckel's model suggests that sediment-dispersal 

patterns were controlled in part by a "thalweg," or linear 

topographic low, that extended south westward from the 

general area of southwestern Pennsylvania. Clastic materials from the two source areas were carried by tributaries to 

the topographic low and ultimately toward a sea that, 

whenever subsidence exceeded deposition, extended northeastward into Pennsylvania from areas in West Virginia and 

Ohio.

Although Meckel's depositional model fits the general pattern of Pennsylvanian sedimentation, especially with 

regard to the two source areas, it neither conforms to nor 

explains major aspects of Early Pennsylvanian deposition. 

For example, marine incursions did not extend into western 

Pennsylvania until the middle part of Middle Pennsylvanian 

time, and marine fauna, generally of a restricted nature,

have been identified only in one to three thin stratigraphic 

zones (generally only inches thick) in Lower Pennsylvanian 

rocks of Ohio, West Virginia, Virginia, and Kentucky 

(Rice, 1984) (fig. 2). In the general area of Meckel's 

topographic low, Middle Pennsylvanian rocks commonly 

overlie Lower Mississippian rocks. During the Early Pennsylvanian, these areas probably were uplands and more 

subject to erosion than to deposition (Wanless, 1975).

DRAINAGE SYSTEMS

Most studies of current directions in basal Pennsylvanian strata in eastern North America indicate a southwesterly transport direction (see, for example, Siever and Potter, 

1956). Along the northwestern margin of the Appalachian 

basin, sub-Pennsylvanian valleys and channels have been 

described in northern Ohio (Lamb, 1911), in western 

Pennsylvania (Ingham and others, 1956), in southern Ohio 

(Fuller, 1955; Couchot, 1972), in northeastern Kentucky 

(Englund and Windolph, 1971), in south-central Kentucky 

(Wixted, 1977; Rice, 1984), and in the Eastern Interior 

basin (Bristol and Howard, 1971). The studies cited 

describe the valley- and channel-fill deposits as Pennsylvanian stream deposits, many of which are composed of 

pebbly or conglomeratic quartz arenite that indicates southerly current directions parallel with the valleys or channels 

(see, for example, figs. 3, 4). The basal quartz arenite 

deposits, although widely separated, are postulated by Rice 

(1984) to derive from the same southwest-flowing river 

system that included the basal Pennsylvanian deposits of the 

Brownsville paleovalley in the Eastern Interior basin (Pryor 

and Potter, 1979). In south-central Kentucky, an area of

Fluvial Deposition in Central Appalachians during Early Pennsylvanian B3
Figure 4. Detail of Pennsylvanian crossbedded quartzpebble conglomerate on Pilot Knob, Levee 7 1/2-minute 

quadrangle, east-central Kentucky, shown in figure 3. 

Brunton compass shown for scale.

extensive Pennsylvanian lag gravels (Miller, 1910) indicates where that river, herein called the Sharon-Brownsville 

river system (fig. 1), breached the Cincinnati arch. The 

stream pattern shown in figure 1 in the area of the Jessamine 

dome suggests that the southwest-dipping paleoslope was 

modified locally by upwarping of the Cincinnati arch in 

Late Mississippian time (Rice and Haney, 1980) and that 

the escarpment southeast of the Sharon-Brownsville river 

system was the drainage divide between the Appalachian 

and Eastern Interior basins at that time.

Paleocurrent directions and thickness contours show 

that the major Pennsylvanian depocenters were along the 

margin of the craton in the Appalachian basin in southeastern West Virginia and southwestern Virginia, in the Black 

Warrior basin of Mississippi and Alabama, and in the 

Arkoma basin of Oklahoma and Arkansas. Thus, in West 

Virginia and parts of Virginia along the eastern margin of 

the Appalachian basin, paleocurrent directions of basal 

Pennsylvanian strata are westerly or northwesterly from the 

evolving Appalachian erogenic belt (see, for example, 

Englund, 1974). In northeastern Kentucky, southeastflowing streams at the base of the Pennsylvanian, such as 

the drainage system mapped by Englund and Windolph 

(1971), also carried detritus to the depocenter from the 

emergent southeastern flank of the Cincinnati arch. In 

southwestern Virginia, much of the depocenter is eroded 

away, and Early Pennsylvanian current directions shift from 

westerly to southwesterly and follow the margin of the 

craton in eastern Kentucky and Tennessee toward the 

southwest (Donaldson and others, 1979).

Although small channels cannot be traced in the 

subsurface by using available drill-hole data, several large 

paleovalleys have been distinguished at the base of the 

Pennsylvanian in West Virginia and easternmost Kentucky. 

Figure 5 is a modification of a map by Flowers (1956) 

showing the thickness of the Greenbrier Limestone in the

38°- 

Figure 5. Isopach map of Mississippian Greenbrier Limestone in West Virginia showing traces and directions of 

flow of inferred paleochannels (indicated by arrows). 

Contour interval 25 ft. Modified from Flowers (1956, pi. 2).

subsurface of West Virginia. The configuration of thickness 

contours indicates that the upper surface of the limestone in 

northwestern West Virginia was beveled and locally deeply 

scoured by subaerial erosion. Depression contours indicate 

a huge sink hole and, together with Flowers' description of 

the systemic boundary, suggest development of a karst 

topography on the Greenbrier in that area in Late Mississippian and Early Pennsylvanian time. Flowers identified 

the large trough outlined by the 100-ft contour in the central 

part of the map as a river paleochannel and, because 

northwest-trending hanging valleys are tributary to the main 

channel, postulated that the channel and its fill of Pennsylvanian quartzose sandstone and conglomerate are the product of a northwest-flowing river. We believe, however, that 

the paleovalley was cut by a south-flowing river for several 

reasons: (1) the regional paleocurrent direction in Early 

Pennsylvanian time was southerly; (2) the paleovalley is 

large and is filled by quartzose sandstone and conglomerate; 

and (3) the paleovalley is cut in bedrock and was situated 

between a continental source of detritus and the rapidly 

subsiding Appalachian basin. Several other scours suggesB4 Evolution of Sedimentary Basins Appalachian Basin
Elkhorn City quadrangle 

USGS Map GQ-9S1

Figure 6. Westward onlap and pinchout of Pennsylvanian Lee Formation in eastern Kentucky. 

Generalized columnar sections from U.S. Geological Survey Geologic Quadrangle Maps GQ-951 

(Alvord and Miller, 1972) and GQ-1126 (Rice, 1973). Subsurface data from core holes drilled for coal 

resource evaluation of Lower Pennsylvanian rocks (Bergeron and others, 1983). The Rockcastle 

Conglomerate Member of the Lee Formation was correlated with the upper sandstone member of the 

Lee Formation by Englund (1968) and by Rice and Smith (1980). c, coal bed; L, linguloid brachiopod; 

P, productoid brachiopod.

live of paleochannels are indicated on the sub-Pennsylvanian surface in figure 5. Because the Greenbrier dips to 

the southeast (see fig. 1), the south-flowing streams cut 

progressively higher stratigraphic levels, and, south of their 

terminations shown in figure 5, the paleochannels are 

entirely in strata of the overlying Mauch Chunk Group.

A southwest-trending linear depression was identified 

in the subsurface at the base of the Pennsylvanian in eastern 

Kentucky (Coskren and Rice, 1979) and is shown in area A 

on figure 1 as a paleovalley. The extension of this paleovalley into southwestern Virginia was described by Rice 

(1985, 1986). The paleovalley is 10 mi wide and more than 

300 ft deep and filled with pebbly and conglomeratic quartz 

arenite of the Lee Formation (fig. 2). The basal Pennsylvanian quartz arenites that occupy a portion of this paleovalley 

are locally brought to the surface by the Pine Mountain 

overthrust fault along part of the Kentucky-Virginia State 

line. Figure 6 contrasts a simplified geologic section for the 

Lee Formation in the central part of the paleovalley (Elkhorn City 7 1/2-minute quadrangle) (Alvord and Miller, 

1972) with one for an upland area west of the paleovalley

(Jenkins West 7V2-minute quadrangle) (Rice, 1973). The 

presence of a paleovalley at the base of the Pennsylvanian in 

the Elkhorn City quadrangle is corroborated by the difference in the thickness of the interval between the Mississippian Little Stone Gap Member of the Pennington Formation 

and the base of the Lee Formation in the two areas. In 

addition, a distinctive 200-ft-thick high-silica (>99.9 percent) conglomeratic sandstone unit at the base of the Lee 

Formation in the central part of the paleovalley in the 

Elkhorn City quadrangle is not in the upland area in the 

Jenkins West quadrangle.

DEPOSITIONS. MODELS

Depositional models for Lower Pennsylvanian rocks 

in the central Appalachian basin must explain the contrast 

between what might be called the "northwestern" and 

"southeastern" facies of the New River Formation (or 

equivalent strata of the Lee Formation) (fig. 2). The

Fluvial Deposition in Central Appalachians during Early Pennsylvanian B5
B

Mojor capture point 

of Sharon River

METAMORPHIC ROCKS

Figure 7. Two interpretations of Early Pennsylvanian paleogeography in the Appalachian basin. A, Area A in figure 1. 

Beach and barrier island model of Miller (1974, fig. 59) in parts of Kentucky, Virginia, and West Virginia. B, Area B in figure 

1. Fluvial model presented in this report. Arrows indicate general location and paleocurrent directions of known deposits 

of basal Pennsylvanian quartz arenite; paleocurrent direction inferred for subsurface data (dashed) (Flowers, 1956; 

Hansen, 1984) Details of streams altered; vertical scale exaggerated for sake of perspective.

northwestern facies is dominated by quartz arenite units, 

which are broadly linear, trend southwest, and locally are 

more than 400 ft thick and 50 mi wide. The quartz arenite 

facies wedges out to the southeast or locally grades into the 

southeastern facies, which is dominated by subgraywacke, 

siltstone, and shale. Figure 1A (Miller, 1974) shows a 

model of the paleogeography during deposition of Lower

Pennsylvanian strata in adjacent areas of Kentucky, Virginia, and West Virginia that is supported by the studies of 

Donaldson (1974, fig. 1), Englund (1974, 1979), Englund 

and others (1979, 1985, 1986), Perm (1974a, b), Perm and 

others (1971), Home (1979), and Home and others (1974). 

In this model, the two facies are genetically related: the 

northwestern facies is represented by the beach and barrier

B6 Evolution of Sedimentary Basins Appalachian Basin
island complex and the southeastern facies by the backbarrier and alluvial complexes. However, marine units 

predicted by the model to represent the foreshore and 

offshore environments in Kentucky and West Virginia have 

never been identified in either State. Proponents of the 

model argue either that the Pennsylvanian quartz arenite is 

a facies of Mississippian marine shale and carbonate units 

(Perm, 1974b; Home and others, 1974) or that the northwestern marine equivalents of the quartz arenite have been 

eroded away (Englund, 1974). We believe that these 

hypotheses are untenable. Available data indicate that the 

Pennsylvanian quartz arenite units onlap the southeastern 

flank of the Cincinnati arch and either fill south- or 

southwest-trending channels in the Mississippian surface 

(such as the Livingston Conglomerate Member of the Lee 

Formation) or, as figure 6 shows, overlie or wedge out to 

the northwest (similar to the Rockcastle Conglomerate 

Member of the Lee Formation) into coal-bearing sequences 

of Pennsylvanian shale and siltstone of the Breathitt Formation. Depositional thinning of the lower part of the Lee 

Formation increases with westward onlap (fig. 6). Core 

hole D2 (fig. 6) was drilled on the western rim of the 

Livingston paleochannel, the base of which is at least 150 ft 

below the base of the Pennsylvanian section in the core hole 

(Brown and Osolnik, 1974). The Livingston channel is 

about 4 mi wide and is filled with interstratified and 

intergraded quartz sandstone and conglomerate deposited 

by a south- to southeast-flowing stream (Rice, 1984). Thus, 

data from the outcrop belts at both ends of the section 

shown in figure 6 suggest that the pre-Pennsylvanian 

surface was terrestrial and had local relief of at least 150 ft. 

A continental environment of deposition for the basal 

Pennsylvanian strata is also indicated by Alvord and Miller 

(1972), who characterized quartz arenites of the Elkhorn 

City area as conspicuously cross stratified in large-scale sets 

and forming persistent channel-in-channel units that contain 

thin, lenticular bodies of interstratified clayey and silty 

sandstone and thin coal beds. Sedimentologic and paleohydrologic studies by BeMent (1976) of outcropping Lower 

Pennsylvanian quartz arenites in areas including area A (fig. 

1) indicate that the arenites were deposited by a southwestflowing braided river. A study by Miller (1974, p. 118) 

suggests that the abundant current and crossbedding structures of those strata are characteristically composed of 

tabular sets of uniformly dipping, planar crossbeds that 

mostly dip 15° to 25° south and southwest (fig. 8). Miller 

noted, however, that "a significant number of low-angle 

laminar and festoon cross-bedding features have a dip to the 

southeast or northwest." Although he attributed these latter 

structures to deposition in a marine beach or barrier-bar 

environment and explained their scarcity as resulting from 

destruction by southwest-migrating tidal channels, he was 

unable to explain the absence of shelly fossils in the arenites 

or associated strata. Confronted with data similar to the 

foregoing, Donaldson and others (1979) reevaluated the

Figure 8. Southeast-inclined tabular sets of crossbedded 

pebbly quartz arenite of basal part of Lee Formation, 

eastern Kentucky. U.S. Highway 119 at crest of Pine 

Mountain, about 3.2 mi south of Whitesburg, Ky. Crossbedding is unidirectional toward southwest. Location of 

photograph shown in figure 6.

paleogeography of Lower Pennsylvanian strata and suggested that plant fossils, textural sequences, and sedimentary structures of the quartz arenites of the New River 

Formation in West Virginia indicate deposition in braided 

rivers.

Our fluvial model for Early Pennsylvanian deposition 

in the Appalachian basin, shown in figure IB, indicates 

inferred drainage configurations and the locations and 

current directions of identified deposits of quartz arenite in 

paleovalleys at the base of the Pennsylvanian. We envision 

the following scenario for Early Pennsylvanian time. Deposition began in the central part of the basin (depocenter) 

and consisted of sequences of sand, silt, clay, and peat, 

which became the Pocahontas Formation (see fig. 2). 

Increased erosion of the uplifted cratonic source area in 

Canada and New York resulted in transport of great

Fluvial Deposition in Central Appalachians during Early Pennsylvanian B7
quantities of quartz sand and gravel into the SharonBrownsville valley and its alluviation. Head ward erosion of 

streams along the southeastern margin of the carbonate 

escarpment flanking the Cincinnati arch led to the capture 

and diversion of the headwaters of the Sharon-Brownsville 

river into the Appalachian basin. The major capture was by 

way of the great valley cut into the Greenbrier Limestone 

described by Flowers (1956) and by us (fig. 5). Thick 

sequences of quartz arenite of the New River and Lee 

Formations represent clastic material transported from 

northern cratonic areas across West Virginia; these 

sequences truncate or disconformably overlie the Pocahontas in the northwestern part of its extent (Englund, 

1974). Braided streams deposited coarse quartzose sediments on delta plains in the subsiding Appalachian basin, 

and the rapid aggradation resulted in construction of extensive sand sheets in the southern and western parts of the 

basin. Detritus in the central part of the basin came mostly 

from source areas to the southeast (Englund, 1974). The 

braided rivers were bordered mostly by freshwater lakes and 

swamps in which clay, silt, and peat were deposited. 

Several transgressive events during the Early Pennsylvanian 

are interpreted to represent the encroachment of seas into 

areas of rapid subsidence in the central part of the basin and 

the local extension of shallow marine or brackish water into 

certain river valleys (Rice, 1984). As regional subsidence 

continued in the Appalachian basin, south-trending Sharon 

channels were alluviated and abandoned. West-flowing 

streams built deltas into the basin, and the delta plain 

extended progressively west from the rising Appalachians. 

These deltaic deposits did not completely displace the 

Sharon system and bury the remnants of the carbonate 

escarpment in northeastern Kentucky until Middle Pennsylvanian time.

CONCLUSIONS

Integration of stratigraphic and sedimentologic information within the Early Pennsylvanian tectonic framework 

for eastern North America suggests that, at the beginning of 

the Pennsylvanian, much of the area was emergent and had 

a southwest-dipping paleoslope. Earliest Pennsylvanian 

deposition in southeastern West Virginia and southwestern 

Virginia was accompanied by headward erosion of streams 

draining the southeastern flank of the developing Cincinnati 

arch and by the capture of major rivers originating in the 

southeastern part of the Canadian Shield and their diversion 

into the subsiding Appalachian basin. A reevaluation of 

Flowers' (1956) subsurface study of the Greenbrier Limestone in West Virginia, including his identification of a 

large south-trending paleovalley at the base of the Pennsylvanian that is filled with pebbly and conglomeratic quartz 

arenite, provides the necessary link between cratonic source 

areas in the Sharon drainage system and vast deposits of

Lower Pennsylvanian pebbly quartz arenite in the Appalachian basin. The channel identified by Flowers is the largest 

of those that diverted streams from the Eastern Interior 

basin into the Appalachian basin, and it greatly affected 

both depositional patterns and facies distribution in the 

Appalachian basin during Early Pennsylvanian time. Our 

fluvial model and the sedimentation history for the Appalachian and Eastern Interior basins furnish a new basis for 

intraregional and interregional correlation of Lower Pennsylvanian strata and for analysis of large and small tectonic 

events in eastern North America during the Early Pennsylvanian.

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the Pennsylvanian System, eastern Ky.: U.S. Geological 

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B8 Evolution of Sedimentary Basins Appalachian Basin
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model for the Mississippian-Pennsylvanian boundary in 

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east-central Ky.: U.S. Geological Survey Geologic Quadrangle Map GQ-1478, scale 1:24,000.

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coal fields were once connected across central Kentucky: 

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Wayne Counties: Kent, Ohio, Kent State University, unpublished M.Sci. thesis, 92 p.

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and Hart Counties, Ky., in Palmer, J.E., and Dutcher, R.R., 

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GQ-1126, scale 1:24,000.

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strata in eastern Kentucky: U.S. Geological Survey Professional Paper 1151-G, 53 p.

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B10 Evolution of Sedimentary Basins Appalachian Basin
Chapter C

Disturbed Zones: Indicators of Subsurface Faults 

and Possible Hydrocarbon Traps in the Valley and 

Ridge and Appalachian Plateau Provinces of 

Pennsylvania, Maryland, Virginia, and West Virginia

By HOWARD A. POHN and TERRI L. PURDY

A multidisciplinary approach to research studies of sedimentary 

rocks and their constituents and the evolution of sedimentary 

basins, both ancient and modern

U.S. GEOLOGICAL SURVEY BULLETIN 1839 

EVOLUTION OF SEDIMENTARY BASINS-APPALACHIAN BASIN

CONTENTS

Abstract Cl

Introduction Cl

Characteristics and morphology Cl

Regional implications C3

Magnitude of displacement C4

Lithotectonic associations C5

Association of disturbed zones and hydrocarbon occurrences C6

Conclusions C6

References cited CIO

FIGURES

1. Map showing location of study area in Valley and Ridge and Appalachian 

Plateau provinces of Appalachian Mountains, Pennsylvania, Maryland, Virginia, and West Virginia C2 

2, 3. Schematic drawings showing:

2. Structural elements in thrust system C3

3. Formation of disturbed zones in various structural settings C3

4. Photograph showing disturbed zone in Devonian Lock Haven (Chemung) 

Formation at Towanda, Pa. C3

5. Schematic drawings showing evolution of disturbed zone at Towanda,

Pa. C4 

6, 7. Simplified structural maps showing:

6. Distribution of faults in part of Hyndman TVz-minute quadrangle, Pennsylvania C4

7. Locations of disturbed zones along extensions of mapped faults in part

of Allegheny County, Maryland. C5

8. Map showing structure of Oriskany Sandstone along part of Deer Park anticline, Preston County, West Virginia C5 

9, 10. Geologic maps showing:

9. Disharmonic fold patterns of formations and relationship between formational contacts and disturbed zones in part of Huntingdon County, 

Pennsylvania C6

10. Relationship between formational flexures and disturbed zone in part of 

Hyndman TVi-minute quadrangle, Pennsylvania C7

11. Block diagrams showing stacked anticlines that have identical surface configurations but considerably different displacements on intervening faults C7

12. Photograph showing zone of wedge faults in Upper Devonian Catskill Formation of Pennsylvania C7 

13, 14. Maps showing:

13. Locations of surface exposures of disturbed zones, structure contours of 

top of Onondaga Formation or equivalent, and locations of subsurface 

thrust fault and oil and gas wells C8

14. Relationship between disturbed zones and gas fields, West Virginia

panhandle C9

15. Schematic cross section showing relationship between concentrations of disturbed zones and areas of high fracture porosity in Oriskany Sandstone and 

reservoir seals in Marcellus and Needmore Shales CIO

Contents III
CONVERSION FACTORS FOR SOME SI METRIC AND U.S. UNITS OF MEASURE

To convert from To Multiply by

Feet (ft) Meters (m) 0.3048

Miles (mi) Kilometers (km) 1.609

Pounds (Ib) Kilograms (kg) .4536

Degrees Fahrenheit (°F) Degrees Celsius (°C) Temp °C=(temp °F-32)/l.

IV Contents
EVOLUTION OF SEDIMENTARY BASINS-APPALACHIAN BASIN

Disturbed Zones: Indicators of Subsurface Faults and 

Possible Hydrocarbon Traps in the Valley and Ridge and 

Appalachian Plateau Provinces of Pennsylvania, Maryland, 

Virginia, and West Virginia

By Howard A. Pohn andTerri L. Purdy

Abstract

Disturbed zones are sequences of severely thrust 

faulted and folded rocks either in the hanging walls or 

footwalls adjacent to thrust faults or between closely 

spaced pairs of thrust faults. They are common in the 

central Appalachian Valley and Ridge province and are 

surface manifestations of imbricate thrust faults that are 

rooted to detachments at depth. The zones are tens to 

hundreds of meters thick and a few kilometers to tens of 

kilometers long. Although they commonly form in units 

composed of alternating siltstone and shale, some are in 

more competent units. The intense folding and faulting in 

disturbed zones may localize domains of high fracture 

porosity in the subsurface, which, when sealed from the 

surface, may produce potential hydrocarbon traps.

INTRODUCTION

The gross aspects of the structural geology of folded 

and faulted Paleozoic rocks of the central Appalachian 

Mountains have been fairly well described by using seismic 

analyses and geologic mapping (Rodgers, 1963; Gwinn, 

1964, 1970; Harris and Milici, 1977; Perry, 1978). One 

type of structural feature, herein referred to as a "disturbed 

zone," has been frequently described (Rickard, 1952, p. 

517), but the relationship between these zones and the 

regional tectonic framework has been given little attention. 

This report discusses the occurrence, morphology, and 

sequential development of these zones.

The disturbed zones described in this paper are in the 

Valley and Ridge and Appalachian Plateau provinces of the 

Appalachian Mountains from central Pennsylvania to northern West Virginia (fig. 1). In this area, a series of folded 

and thrust-faulted Paleozoic rocks trend east-northeast to 

northeast. The sedimentary sequence comprises predominantly carbonate rocks of Cambrian through Ordovician age

and clastic rocks of Ordovician through Pennsylvanian age 

and is 7,800 to 10,200 m thick.

Seismic profiles and drilling data indicate that both 

the Valley and Ridge province and a large part of the 

Appalachian Plateau province are underlain by large thrust 

sheets that have been translated westward along a thrust 

system consisting of extensive bed-parallel flats (decollements), ramps, and imbricate splay faults (fig. 2). This type 

of structural architecture is indicative of thin-skinned tectonic systems in which the deformation is concentrated 

above the basal detachment and the basement is virtually 

undeformed (Rodgers, 1963; Gwinn, 1964; Dahlstrom, 

1970; Boyer and Elliott, 1982; Butler, 1982). Disturbed 

zones are common throughout the study area, and we 

believe that such structures are characteristic of thrust belts 

worldwide.

Acknowledgments. The authors are grateful to 

Robert C. Milici (Virginia Division of Mineral Resources) 

and William M. Dunn (Department of Geology, West 

Virginia University) for their insightful reviews and helpful 

comments during the writing of this paper. Field data 

collected by C. Scott Southworth of the U.S. Geological 

Survey aided the study.

CHARACTERISTICS AND MORPHOLOGY

The term "disturbed zone" was first used by Rickard 

(1952, p. 517) to describe precisely the structures discussed 

below. Disturbed zones consist of intensely folded and 

thrust-faulted beds either in the hanging wall or footwall 

adjacent to a thrust fault or in a zone between a closely 

spaced pair or within a series of approximately parallel 

thrust faults (fig. 3). Beds within a disturbed zone are 

intensely deformed, whereas beds adjacent to the zone are 

relatively undeformed. Disturbed zones are tens to hundreds

Manuscript approved for publication, 5/16/88 Disturbed Zones: Indicators of Subsurface Faults and Possible Hydrocarbon Traps C1
80

38

PENNSYLVANIA

WEST 

VIRGINIA r^'

Figure 1. Location of study area in Valley and Ridge and Appalachian Plateau provinces of Appalachian 

Mountains, Pennsylvania, Maryland, Virginia, and West Virginia. Boundaries of Great Valley (east) and 

Appalachian structural front (west) indicated by dotted lines.

of meters thick and commonly can be traced for a few 

kilometers to tens of kilometers along strike. They can be 

distinguished from horse blocks or duplexes (fig. 2) because 

horse blocks and duplexes are not necessarily intensely 

folded or faulted in the fault-bounded block.

The thrust faults that bound disturbed zones can be 

either bed parallel or bed oblique. Although bed-parallel 

disturbed zones are similar in appearance to drag folds, they 

are different from drag folds in that disturbed zones are not 

restricted to the limbs of a host fold, generally contain more 

intensely deformed rocks, and may show opposite senses of 

rotation of axial planes of folds within the fault blocks.

Field mapping in the study area demonstrates an 

abundance of disturbed zones. At several locations, the 

entire width of a zone is exposed, and the morphology of 

the zone can be described in detail. An excellent example of 

a well-exposed disturbed zone occurs at Towanda, Pa., 80 

km north of the study area (fig. 4). This bed-oblique 

disturbed zone is bounded by a pair of thrust faults, and the 

total displacement to the south along the faults is greater 

than 15 m. The antithetic or back-thrusted disturbed zone, 

in the siltstone and shale of the Devonian Lock Haven 

(Chemung) Formation, evolved from a series of horse 

blocks that imbricated successively in a piggyback fashion

C2 Evolution of Sedimentary Basins Appalachian Basin
Figure 2. Structural elements in thrust system.

(fig. 5). Individual horse blocks were internally deformed 

by compression and drag, and concomitant thickening 

occurred. Many folds within individual horse blocks are 

asymmetric, and one limb commonly is vertical to overturned. These folds may themselves be cut by thrust or 

extension faults. Shaly beds generally have been deformed 

in response to disharmonic folding between resistant units.

fl

Figure 3. Formation of disturbed zones. A, In hanging 

wall of thrust fault. B, Between pair of thrust faults. C, In 

footwall of thrust fault.

REGIONAL IMPLICATIONS

Disturbed zones have been noted by many field 

geologists and identified as "crumpled" (Root, 1977), 

"tightly folded or otherwise contorted on a small scale" 

(Miller, 1959; Conlin and Hoskins, 1962; Dyson, 1963; 

deWitt, 1974), or "contorted" (Hoskins, 1976). These 

structures have never before been interpreted as being the 

surface expressions of regional fault systems, but, in our 

opinion, they are precisely that for the following reasons. 

First, many disturbed zones are associated with mapped 

faults. Figure 6 shows a map of surface thrust faults in part 

of the Hyndman 7V2-minute quadrangle, Pennsylvania 

(deWitt, 1974). Most of the disturbed zones that we mapped 

in this area occur along faults mapped by deWitt (1974). 

Second, many disturbed zones are found along extensions 

of mapped faults (fig. 7). Third, disturbed zones commonly 

occur along upward extensions of faults that were mapped 

in the subsurface on the basis of well control or seismic 

interpretation. Gwinn (1964, p. 872), for example, showed 

that thrust faults in the subsurface, as determined from 

seismic and drill-hole data, are found on both sides of the 

Deer Park anticline in Preston County, W. Va., and we 

mapped disturbed zones along the surface projections of 

these faults (fig. 8). Fourth, disturbed zones commonly 

occur along contacts of disharmonically folded stratigraphic 

units. Figure 9 shows an area in Huntingdon County, 

Pennsylvania, in which numerous disturbed zones are in 

Silurian rocks along the contacts between the Clinton Group 

and the Mifflintown Formation and between the Bloomsburg Formation and the Wills Creek Formation. The same 

formational contacts show disharmony throughout much of 

Pennsylvania, Virginia, and West Virginia, and extensive 

disharmonic fold patterns strongly suggest the presence of 

decollements (James Parley, oral communication, 1980;

Figure 4. Disturbed zone in Devonian Lock Haven (Chemung) Formation at Towanda, Pa., about 80 km north of 

the study area. Details of geometry of this bed-oblique 

disturbed zone that formed between a pair of thrust faults 

are shown in figure 5.

Disturbed Zones: Indicators of Subsurface Faults and Possible Hydrocarbon Traps C3
39P50'

78°45'

Figure 5. Evolution of disturbed zone at Towanda, Pa. 

Zone is shown in figure 4.

Pohn and Purdy, 1982). In the example shown in figure 9, 

the decollements (bed-parallel disturbed zones) have been 

folded.

These examples are evidence that disturbed zones are 

surface expressions of thrust faults rooted in the subsurface. 

We believe that, in areas where disturbed zones and mapped 

flexures are coincident, these flexures represent duplication 

of the stratigraphic sequence by faulting. An example of the 

association of flexures and disturbed zones occurs in the 

Hyndman TW-minute quadrangle, Pennsylvania (de Witt, 

1974) (fig. 10). If a line is drawn between the two flexures 

in the Keyser Limestone (locations A and B, fig. 10), it will

39P461

KILOMETERS

Figure 6. Distribution of faults in part of Hyndman 71/2- 

minute quadrangle, Pennsylvania. Asterisks, disturbed 

zones; solid lines, faults (barbs on upper plate); dashed 

lines, inferred faults; dotted lines, concealed faults. Modified from deWitt (1974).

pass directly through the disturbed zone at location C; we 

believe that the presence of the disturbed zone indicates that 

the flexures result from duplication by a thrust fault denoted 

by the disturbed zone. This conclusion is supported by 

Wallace deWitt, Jr. (oral communication, 1982), who 

originally mapped the zone as "tightly folded rocks."

MAGNITUDE OF DISPLACEMENT

Many disturbed zones are intraformational in that 

rocks in the hanging wall and footwall belong to the same 

stratigraphic unit and therefore appear to have only small 

displacement; however, intraformational faults may have 

large displacements. Stacked anticlines in the Valley and 

Ridge province (fig. 11) are similar to those in the Canadian

C4 Evolution of Sedimentary Basins Appalachian Basin
79°00'

39°30'

Miss-Penn 

undifferentiated

Dhn

WEST 

VIRGINIA

Do

DShk

79°45' 

39°20'

79°30'

KILOMETERS

Figure 7. Locations of disturbed zones along extensions 

of mapped faults in part of Allegheny County, Maryland. 

Solid circles, disturbed zones; heavy lines, faults. Dh, 

Hampshire Formation; Dch, Chemung Formation 

(including Parkhead Sandstone, Brallier Formation, and 

Harrell Shale); Dhn, Hamilton Group; Do, Ridgeley Sandstone and Shriver Chert; DShk, Helderburg Formation 

and Keyser Limestone; Stl, Tonoloway Limestone; Swb, 

Wills Creek Shale and Bloomsburg Formation. Compiled 

from geologic maps of West Virginia (Cardwell and others, 

1968) and Maryland (Cleaves and others, 1968; used with 

permission of Maryland Geological Survey). Fault extending toward three disturbed zones in West Virginia is not 

shown on West Virginia geologic map.

Rocky Mountains that have been described as adjacent 

anticlines juxtaposed by thrust faulting (Dahlstrom, 1970). 

In the study area, we identified numerous examples 

of stacked anticlines in which the apparent intervening 

syncline is occupied by faults or by disturbed zones. Figure 

11 shows two examples of stacked anticlines that have 

virtually identical map patterns but considerably different 

displacements along the intervening faults. Seismic reflection surveys or closely spaced drill holes may be required to 

determine the amount of displacement on these faults.

39°05

012345 .... I . .' MILES

0135 7 KILOMETERS

Figure 8. Structure of Oriskany Sandstone along part of 

Deer Park anticline, Preston County, West Virginia. Contours are of depth to top of Oriskany Sandstone; contour 

interval, 1,000 ft. Dotted lines, uplimb thrusts mapped by 

Gwinn (1964) from seismic reflection and drill-hole data; 

solid circles, disturbed zones; dashed lines, surface representation of faults as inferred from locations of disturbed zones. Modified from Gwinn (1964).

LITHOTECTONIC ASSOCIATIONS

Disturbed zones in the study area generally are in 

incompetent, thick sequences of shale and thin-bedded 

siltstone, including the Lock Haven (Chemung), Brallier, 

and Marcellus Formations of Devonian age. In more competent units, such as the thick-bedded sandstone of the 

Catskill Formation of Late Devonian age, clusters of wedge 

faults (fig. 12) are in extensive exposures that otherwise 

contain unfaulted beds. The subjacent Lock Haven (Chemung) Formation contains many more disturbed zones than 

any other formation in the study area. Although some of 

these faults most likely continue upward, relatively few 

disturbed zones are in the Catskill Formation. We believe 

that disturbed zones in the incompetent units manifest 

themselves as large (meters to tens of meters displacement) 

wedge faults in competent units.

Disturbed Zones: Indicators of Subsurface Faults and Possible Hydrocarbon Traps C5
4Cf37'30"

Swc

I

KILOMETERS

Figure 9. Disharmonic fold patterns of formations and relationship between formational contacts and disturbed zones 

in parts of Pine Grove Mills, McAlevy's Fort, Donation, and Allensville quadrangles, Huntingdon County, Pennsylvania. 

Asterisks, disturbed zones; heavy lines, faults. Dh, Hamilton Croup; Doo, Onondaga and Old Port Formations, 

undivided; Dor, Ridgely Member of the Old Port Formation; DSkt, Keyser and Tonoloway Formations, undivided; Swc, 

Wills Creek Formation; Sbm, Bloomsburg and Mifflintown Formations, undivided; Sc, Clinton Croup; St, Tuscarora 

Formation; Oj, Juniata Formation; Obe, Bald Eagle Formation. Geology modified from Berg and Dodge (1981).

ASSOCIATION OF DISTURBED ZONES AND 

HYDROCARBON OCCURRENCES

disturbed zones and the relationship between these zones 

and certain hydrocarbon traps.

Field mapping shows the coincidence of concentrations of disturbed zones and lines of gas wells, which are 

slightly offset from and parallel with the concentrations of 

disturbed zones (figs. 13, 14). This association can be 

understood by examining a schematic cross section of such 

a concentration (fig. 15). Folding and extreme wedge 

faulting in a competent formation such as the Oriskany 

Sandstone considerably increase the fracture porosity of the 

formation. The same faults that fracture competent formations are taken up by flowage and concomitant disharmonic 

folding in superjacent incompetent shale beds, such as the 

Needmore and Marcellus Formations, and produce disturbed zones that serve to seal the reservoir. Detailed 

mapping of disturbed zones in overthrust belts will result in 

a better understanding of both the structural setting of

CONCLUSIONS

Disturbed zones are intensely folded and thrustfaulted beds in the hanging wall or footwall of thrust faults 

or in zones between closely spaced pairs or series of 

approximately parallel thrust faults. They are surface 

expressions of thrust faults rooted in the subsurface to 

detachments or ramps. The zones are tens to hundred of 

meters thick and kilometers to tens of kilometers long.

Disturbed zones are common throughout the central 

Appalachian Valley and Ridge and Appalachian Plateau 

provinces, and we believe that such structures are characteristic of thrust belts worldwide. They are more abundant 

in incompetent units and are manifested as wedge faults in 

competent units. Although concentrations of disturbed

C6 Evolution of Sedimentary Basins Appalachian Basin
78°43'OO" 

39° 51'

78° 41 "30"

39°50'

-B

Ridgeley Sandstone 

Shriver Formation

| Dm* I

New Creek and Corriganville Limestone 

and Mandate Formation

Keyser Limestone

| SH | 

Tonoloway Limestone

| Sv»T"|

Wills Creek Formation

| Sb 1

Bloomsburg Red Beds

.5

KILOMETERS

Fault 

Sawteeth on upper plate

Figure 10. Relationship between formational flexures (A, B) and disturbed zone (C) in part of 

Hyndman 7 1/2-minute quadrangle, Pennsylvania (deWitt, 1974). Symbol at letter C is deWitt's symbol for 

"tightly folded rocks."

Figure 11. Stacked anticlines that have identical surface 

configurations but considerably different displacements 

on intervening faults.

zones are commonly associated with hydrocarbon occurrences, the converse is not necessarily true, and careful 

mapping of disturbed zones may be used to augment 

hydrocarbon exploration techniques in thrust belts.

Figure 12. Zone of wedge faults in Upper Devonian 

Catskill Formation of Pennsylvania. Wedge faults in competent units probably are structural equivalents of disturbed zones in incompetent units. Note open wedge 

fractures, higher joint density, and shattered sandstone in 

region of wedge faults, all of which lead to increases in 

fracture porosity.

Disturbed Zones: Indicators of Subsurface Faults and Possible Hydrocarbon Traps C7
78P37'30"

39°30'

39°15'

EXPLANATION

THRUST FAULT IN SUBSURFACE v 

DISTURBED ZONE AT SURFACE - 

PRODUCING WELL -# 

SHOW OF GAS -^ 

DRY HOLE -$ 

KILOMETERS

<

Figure 13. Locations of surface exposures of disturbed zones, structure contours (interval 

1,000 ft) of top of Onondaga Formation or equivalent, and locations of subsurface thrust 

fault and oil and gas wells. Modified from Cardwell (I982).

C8 Evolution of Sedimentary Basins Appalachian Basin
79POO' 78°30'

39P30

39POO'

MARYLAND '-

<

K

V

WEST VIRGINIA

 r- VIRGINIA

10 is 20

i MILES 

KILOMETERS

/

Figure 14. Relationship between disturbed zones (solid circles and dashed lines) and gas 

fields (patterned areas), West Virginia panhandle. Numerals indicate number of disturbed

zones.

Disturbed Zones: Indicators of Subsurface Faults and Possible Hydrocarbon Traps C9
w

CONCENTRATION

OF 

DISTURBED ZONES

MARCELLUS SHALE

NEEDMORE SHALE 

RISKANY SANDSTONE

FRACTURES

MARCELLUS SHALE

NEEDMORE SHALE 

i3V)RISKANY SANDSTONE

DECOLLEMENT

Figure 15. Relationship between concentrations of disturbed zones and areas of high fracture porosity in Oriskany 

Sandstone and reservoir seals in Marcellus and Needmore Shales.

REFERENCES CITED

Berg, T.M., and Dodge, C.M., compilers, 1981, Preliminary 

geologic quadrangle maps of Pennsylvania: Pennsylvania 

Geological Survey Map 61, 636 p., scale 1:62,500.

Boyer, S.E., and Elliott, D., 1982, Thrust systems: American 

Association of Petroleum Geologists Bulletin, v. 66, no. 9, p. 

1196-1230.

Butler, R.W.H., 1982, The terminology of structures in thrust 

belts: Journal of Structural Geology, v. 4, no. 3, p. 239-245.

Cardwell, D.H., 1982, Oriskany and Huntersville gas fields of 

West Virginia: West Virginia Geological and Economic 

Survey Mineral Resource Series MRS-5 A, p. 43.

Cardwell, D.H., Erwin, R.B., and Woodward, H.P., compilers, 

1968, Geologic map of West Virginia: Morgantown, W. Va., 

West Virginia Geologic and Economic Survey, 2 sheets, 

scale 1:250,000.

Cleaves, E.T., Edwards, J., Jr., and Glaser, J.D., compilers, 

1968, Geologic map of Maryland: Baltimore, Maryland 

Geological Survey, scale 1:250,000.

Conlin, R.R., and Hoskins, D.M., 1962, Geology and mineral 

resources of the Mifflintown quadrangle, Pa.: Pennsylvania 

Geological Survey Topographic and Geologic Atlas of Pennsylvania 126, 46 p.

Dahlstrom, C.D.A., 1970, Structural geology in the eastern 

margin of the Canadian Rocky Mountains: Canadian Petroleum Geology Bulletin, v. 18, no. 3, p. 332-406.

deWitt, W., Jr., 1974, Geologic map of the Beans Cove and 

Hyndman quadrangles and part of the Fairhope quadrangle, 

Bedford County, Pa.: U.S. Geological Survey Miscellaneous 

Investigations Map 1-801, 6 p., scale 1:24,000.

Dyson, J.L., 1963, Geology and mineral resources of the northern 

half of the New Bloomfield quadrangle: Pennsylvania Geological Survey Topographic and Geologic Atlas of Pennsylvania 137ab, 4th ser., 63 p.

Gwinn, V.E., 1964, Thin-skinned tectonics in the Plateau and 

northwestern Valley and Ridge provinces of the central 

Appalachians: Geological Society of America Bulletin, v. 75, 

no. 9, p. 863-900.

 1970, Kinematic pattern and estimates of lateral shortening, Valley and Ridge and Great Valley provinces, central 

Appalachians, south-central Pa., in Fischer, G.W., Pettijohn, 

F.J., Reed, J.C., Jr., and Weaver, K.N., eds., Studies of 

Appalachian geology, central and southern: New York, 

Wiley-Interscience, p. 127-146.

Harris, L.D., and Milici, R.C., 1977, Characteristics of thinskinned style of deformation in the southern Appalachians, 

and potential hydrocarbon traps: U.S. Geological Survey 

Professional Paper 1018, 40 p.

Hoskins, D.M., 1976, Geology and mineral resources of the 

Millersburg 15-minute quadrangle, Dauphin, Juniata, Northumberland, Perry, and Synder Counties, Pa.: Pennsylvania 

Geological Survey Topographic and Geologic Atlas of Pennsylvania 146, 4th ser.

C10 Evolution of Sedimentary Basins Appalachian Basin
Miller, J.T., 1959, Geology and mineral resources of the Loysville quadrangle: Pennsylvania Geological Survey Topographic and Geologic Atlas of Pennsylvania 127, 4th ser.

Perry, W.J., Jr., 1978, Sequential deformation in the eastern 

Appalachians: American Journal of Science, v. 278, p. 

518-542.

Pohn, H.A., and Purdy, T.L., 1982, Disturbed zones: Indicators 

of deep-seated subsurface faults in the Valley and Ridge and 

Appalachian structural front of Pennsylvania: U.S. Geological Survey Open-File Report 82-967, 42 p.

Rickard, L.V., 1952, The Middle Devonian Cherry Valley limestone of eastern New York: American Journal of Science, v. 

250, p. 511-522.

Rodgers, J., 1963, Mechanics of Appalachian foreland folding in 

Pennsylvania and West Virginia: American Association of 

Petroleum Geologists Bulletin, v. 47, no. 8, p. 1527-1536.

Root, S.I., 1977, Geology and mineral resources of the Harrisburg 

West area, Cumberland and York Counties, Pa.: Pennsylvania Geological Survey Topographic and Geologic Atlas of 

Pennsylvania 148ab, 4th ser.

References Cited C11

CHAPTER D

Reevaluation of Conodont Color Alteration Patterns 

in Ordovician Rocks, East-Central Valley and Ridge 

and Western Blue Ridge Provinces, Tennessee

By RANDALL C. ORNDORFF, ANITA G. HARRIS, and 

ARTHUR P. SCHULTZ

A multidisciplinary approach to research studies of sedimentary 

rocks and their constituents and the evolution of sedimentary 

basins, both ancient and modern

U.S. GEOLOGICAL SURVEY BULLETIN 1839 

EVOLUTION OF SEDIMENTARY BASINS-APPALACHIAN BASIN

CONTENTS

Abstract Dl

Introduction Dl

Evaluation of color alteration index data D4

Geologic interpretation D6

Conclusions D9

References cited D9

FIGURES

1. Generalized geologic map of central eastern Tennessee showing conodont 

color alteration index sample localities D2

2. Map showing conodont color alteration index localities and isograds for 

Ordovician carbonate rocks east of the Saltville fault, central eastern 

Tennessee D3

3. Generalized cross section from the Dumplin Valley fault through the Tuckaleechee Cove window D4 

4, 5. Maps showing:

4. Conodont color alteration index localities and revised isograds for 

Ordovician carbonate rocks east of the Saltville fault, central eastern 

Tennessee D7

5. Unrestored thickness of Ordovician rocks younger than the Lenoir

Limestone in the Saltville and Dumplin Valley thrust belts, central eastern Tennessee D8

TABLE

1. Ordovician conodont color alteration index localities used in this report D5

CONVERSION FACTORS FOR SOME SI METRIC AND U.S. UNITS OF MEASURE

To convert from To Multiply by

Feet (ft) Meters (m) 0.3048

Miles (mi) Kilometers (km) 1.609

Pounds (Ib) Kilograms (kg) .4536

Degrees Fahrenheit (°F) Degrees Celsius (°C) Temp °C=(temp °F-32)/1.8

Contents III

EVOLUTION OF SEDIMENTARY BASINS-APPALACHIAN BASIN

Reevaluation of Conodont Color Alteration Patterns in 

Ordovician Rocks, East-Central Valley and Ridge and 

Western Blue Ridge Provinces, Tennessee

By Randall C. Orndorff, Anita G. Harris, and Arthur P. Schultz

Abstract

An anomalously low conodont color alteration index 

(CAI) has been reported for Ordovician rocks in the 

Tuckaleechee Cove window of the Blue Ridge province in 

previous investigations. These data encouraged hydrocarbon explorationists to consider the eastward extension of 

Valley and Ridge rocks beneath thrust sheets of the Blue 

Ridge as a potential hydrocarbon province. Reevaluation 

of old and new CAI data in the easternmost thrust belt of 

the Valley and Ridge province and in windows through the 

Blue Ridge in central eastern Tennessee shows that, 

although the CAI anomaly in the Tuckaleechee Cove 

window is of less magnitude than first reported, CAI 

values for rocks in the window are still lower than those in 

correlative rocks northward and northwestward at the 

eastern limit of the Valley and Ridge province. CAI patterns in Lower and lower Middle Ordovician rocks in 

central eastern Tennessee are more complex than those 

shown by earlier investigations, and the patterns may be 

related to primary depositional and burial trends in Middle and Upper Ordovician chiefly clastic rocks. CAI values 

in Ordovician rocks of the Tuckaleechee Cove window are 

slightly lower than those in correlative rocks in nearby 

windows; a similar pattern exists in the Dumplin Valley 

thrust belt opposite the windows and may reflect thickness patterns of Middle and Upper Ordovician rocks. The 

area of hydrocarbon potential for Valley and Ridge rocks 

beneath the crystalline rocks of the Blue Ridge is somewhat less than previous estimates; these rocks, however, 

still have thermal potential for natural gas but are probably 

beyond the thermal limit for liquid hydrocarbons.

INTRODUCTION

Maps showing thermal maturation patterns in Paleozoic rocks in the Appalachian basin based on conodont 

color alteration indices (CAI) were first presented by 

Epstein and others (1977). Subsequently, Harris and others 

(1978) published more detailed maps of the same area.

These early studies showed that, in most of the Valley and 

Ridge province, thermal maturation patterns in Paleozoic 

rocks are generally related to overburden thickness established before Alleghanian thrusting. In general, CAI values 

increase eastward and reflect the eastward increase in 

thickness of Paleozoic rocks. Some exceptions that are 

structurally controlled are in Lower and Middle Ordovician 

rocks along the eastern limit of the Valley and Ridge 

province. CAI values in the westernmost thrust sheet of the 

Taconic allochthon in New York, in the Jutland klippe in 

New Jersey, and in the Hamburg klippe in Pennsylvania 

(Harris and others, 1978; Harris, 1979) are all significantly 

lower than those in parautochthonous rocks with which they 

are juxtaposed. Thus far, the only other noteworthy reversal 

in thermal maturation patterns near the eastern limit of the 

Valley and Ridge province has been found in the western 

Blue Ridge province, in windows through the Great Smoky 

thrust sheet in central eastern Tennessee (figs. 1, 2). An 

anomalously low CAI value of 2 reported from Ordovician 

rocks of the Tuckaleechee Cove window (Epstein and 

others, 1977; Harris and others, 1978) indicates thermal 

potential for hydrocarbons in sedimentary rocks that underlie crystalline rocks of the Blue Ridge thrust sheets (fig. 3). 

The CAI of rocks in this window was reported to be two 

indices lower than values in correlative rocks 15 to 20 km to 

the west at the eastern limit of the Valley and Ridge 

province. Regional structural interpretations (Woodward, 

1985) show that rocks in the windows are thrust slices 

having duplex geometry (fig. 3). The slices were derived 

from a tectonic ramp below the western part of the Blue 

Ridge province. A similar interpretation was put forth for 

rocks in the windows of southwestern Virginia (Schultz and 

Anders, 1985; Schultz, this volume), but, in that area, CAI 

values and geochemical data (Schultz, this volume) indicate 

that little to no hydrocarbon potential exists east of the 

western edge of the Blue Ridge province. Thus far, the 

Tuckaleechee Cove thermal low has not been explained 

either structurally or sedimentologically. The apparent

Manuscript approved for publication, 5/16/88 Reevaluation of Conodont Color Alteration Patterns, Ordovician of Tennessee D1
MISSISSIPPIAN AND 

UPPER DEVONIAN ROCKS

UPPER AND MIDDLE ORDOVICIAN 

CHIEFLY CLASTIC ROCKS

MIDDLE ORDOVICIAN TO MIDDLE CAMBRIAN 

CHIEFLY CARBONATE ROCKS

LOWER CAMBRIAN AND 

PRECAMBRIAN ROCKS

THRUST FAULT

SAWTEETH ON UPPER PLATE

CONODONT SAMPLE LOCALITY

o

PRODUCTIVE BARREN

iXv-'r-' x '';TE-> l1 r! "!< 5r'' -'-'\~iii- 'rUA ' Li^bUHu.y,-;/-^ ^',~:.'i\-<i\i- uj \o

TUCKALEECHEE 

COVE WINDOW

Figure 1. Generalized geologic map of central eastern Tennessee showing conodont color alteration index 

and strat.graphic data are shown for each numbered sample locality in table 1. Line of section A-A' (fig. 3) 

rial CIGlTlciri \ I _/OQJ *
n

o

I

TUCKALEECHEE 

COVE WINDOW

CALDERWOOD 

\S WINDOW

~l I r i "n r

0 51015 20 25 30 KILOMETERS

 3 

 

Figure 2. Conodont color alteration index localities and isograds for Ordovician carbonate rocks ea

Tennessee. Slightly modified from Harris and others (1978).
NW 

A

SE 

A'

DUMPLIN

VALLEY

FAULT

GUESS

TUCKALEECHEE

WILDWOOD FAULT GREAT SMOKY COVE 

FAULT ^ .-FAULT

0

1 

0

1

5

5 

1

1 

10

I

15

10 MILES 

I

KILOMETERS

NO VERTICAL EXAGGERATION

Figure 3. Generalized cross section from the Dumplin Valley fault through the Tuckaleechee Cove window. p , 

Precambrian and Lower Cambrian rocks; , Cambrian rocks of the Rome Formation through the Conococheague 

Limestone; O k, Upper Cambrian and Lower Ordovician rocks of the Knox Group; Oum, Middle and Upper Ordovician 

rocks. Line of section is shown in figure 1. Modified from Roeder and others (1978) and Woodward (1985).

thermal anomaly may be the result of rapid eastward 

thinning of overburden above the Ordovician rocks exposed 

in the window. Alternatively, geochemical and (or) physical factors may have kept these rocks from reaching the 

same thermal maturity as correlative rocks both along strike 

to the north or across strike to the west at the eastern limit 

of the Valley and Ridge province. The Canning basin in 

Australia, for example, contains as much as 6,500 m of 

post-Precambrian sedimentary rocks that are flat lying to 

gently deformed. In a study of the geothermal history of this 

basin, Nicoll and Goiter (1984) showed that differences in 

CAI values at equivalent depths in bore holes having similar 

stratigraphy are not related to overburden but rather to 

differences in thermal conductivity of basin sediments, 

hydrology, and heat flow patterns. Similar factors could 

have produced local variations in CAI patterns early in the 

evolution of the Appalachian basin. 

The relatively low organic maturation levels reported from 

Ordovician rocks that structurally underlie the chiefly crystalline rocks of the western Blue Ridge in central eastern 

Tennesee have encouraged hydrocarbon explorationists to 

consider this area a potential natural gas province (Harris 

and others, 1981). In addition, seismic interpretations of 

this region (Cook and others, 1979, 1983; Harris and Bayer, 

1979; Milici and others, 1979) have encouraged further 

speculations concerning this frontier hydrocarbon province. 

Hydrocarbon-bearing Paleozoic sedimentary rocks appear 

to extend from surface exposures in the Valley and Ridge 

province of the Appalachian foreland eastward below thrust 

sheets of metamorphic rocks of the Blue Ridge and Piedmont provinces. Palinspastic reconstructions of the eastern 

thrust belt in Tennessee (Harris and others, 1981) show that 

the area of hydrocarbon potential in the subsurface may equal that of known production to the west. A less 

optimistic view was presented by Hatcher (1982), who 

summarized a variety of geologic data and concluded that 

the area of hydrocarbon potential was limited to a relatively 

narrow zone in the westernmost Blue Ridge province in the 

southern half of Tennessee, western North Carolina, and 

northern Georgia. Despite this view, others (Cook and 

others, 1983) have continued to speculate that a sizable part 

of the subsurface beneath the Blue Ridge and Piedmont 

provinces has commercial potential for natural gas. The 

purpose of this investigation was to verify and explain the 

anomalously low CAI of Ordovician rocks of the Tuckaleechee Cove window. This anomalously low value has 

important implications for understanding the geologic 

framework of the area and its implications for hydrocarbon 

potential.

Acknowledgments. -We wish to thank R.D. Hatcher 

Jr., (Department of Geological Sciences, University of 

Tennessee) and R.C. Milici (Virginia Division of Mineral 

Resources) for technical review of the manuscript. We also 

wish to thank the U.S. Park Service for access to Cades 

Cove.

EVALUATION OF COLOR ALTERATION INDEX 

DATA

Examination of the CAI data base used by Harris and 

others (1978) shows that conodonts from rocks in only two 

windows through the Great Smoky thrust sheet were 

indexed (fig. 2); of these, only rocks in the Tuckaleechee 

Cove window produced an anomalously low CAI value in 

comparison with values in the adjacent Valley and Ridge 

province. Moreover, correlative rocks in the easternmost

D4 Evolution of Sedimentary Basins Appalachian Basin
Table 1. Ordovician conodont color alteration index (CAI) localities used in this report

[Sample localities and geologic information shown in fig. 1. Localities without U.S. Geological Survey (USGS) collection numbers are from the collections 

of S.M. Bergstrom and are reposited in the Department of Geology and Mineralogy, Ohio State University, Columbus, Ohio. Asterisk indicates sample 

was collected for this study; all others are from Harris and others (1978). Dolostone was sampled at localities 7, 15, 16, and 34; all other samples are from 

limestone]

Locality 

no.

1 ........

2 ........

3 ........

4 ........

5 ........

6 ........

7 ........

8 ........

9 ........

10 .......

11 .......

12 .......

13 .......

14 .......

15 .......

16 .......

17 .......

18 .......

19 .......

20 .......

21 .......

22 .......

23 .......

24 .......

25 .......

26 .......

27 .......

28 .......

29 .......

30 .......

31 .......

32 .......

33 .......

34 .......

35 .......

36 .......

37 .......

38 .......

39 .......

40 .......

41 .......

42 .......

43 .......

44 .......

45 .......

46 .......

Field no. 

(USCS colln. no.)

. . .*SOCW-30 (10451-CO)

...T-O-77(10576-CO)

. . .T-O-76 (10575-CO)

. . .*SOVO-50 (10549-CO)

*SOCC-26 (10449-CO)

. . .*SOVO^9 (10548-CO)

...*SOCC-25 (10448-CO)

...*SOTA-51 (10550-CO)

. . .70B9^

...*SOTC-23 (10447-CO)

...*SOTC-16(10444-CO)

. . .*SOTC-53 (10552-CO)

...70B11-2

...*SOTC-18(10445^CO)

. . .*SOBH^8 (10547-CO)

...*SOBH-52 (10551-CO)

...*SOLR-34(10453^CO)

. . .70B29-2

. . .64B6-2

...71B8

...74B36-3

...70B10-5

. . .*SOWW^5 (10546-CO)

. . .*SOWW^W (10545-CO)

. . .T-O-79 (10577-CO)

. . .T-CMO (10574-CO)

...*SONE-60(10559-CO)

...T-O-11 (10573^CO)

...*SOWP-59(10558^CO)

. . .*SOCH-62 (10560^CO)

. . .73B8-2

. . .T-O-81 (10578^CO)

...*SODD-57(10556-CO)

...*SOSG-58(10557-CO)

. . .74B38-1

. . .70B8-2

...*SOWC-38(10455^CO)

...*SOWC-10(10443^CO)

...*SOPF-43(10544-CO)

...*SOFG^t(10440^CO)

. ..*SOFG-5 (10441-CO)

...*SOPF-42(10543-CO)

...*SOBC-55 (10554-CO)

...*SOBC-56(10555^CO)

...*SOSG-63(10561-CO)

...*SOBC-54(10553^CO)

County

Blount

do.

do.

do.

do.

do.

do.

do.

do.

do.

do.

do.

do.

do.

do.

do.

do.

do.

do.

do.

do.

do.

do.

do.

do.

do.

do.

do.

do.

do.

do.

Monroe

Sevier

do.

do.

do.

do.

do.

do.

do.

do.

do.

7-minute 

quadrangle

Calderwood

do.

do.

Vonore

Cades Cove

Vonore

Binfield

Wear Cove

Blockhouse

Kinzel Springs

Blockhouse

do.

do.

Concord

do.

do.

do.

Hartford

do.

White Pine

Chestnut Hill

Douglas Dam

do.

do.

do.

Gatlinburg

Wear Cove

Pigeon Forge

Richardson Cove

do.

Pigeon Forge

Boyds Creek

do.

Shady Grove

Boyds Creek

Latitude/longitude

(N./W.)

35°30.6'/83°59.4'

35°30.7'/83°59.9'

35°30.4'/83°59.6'

35°35.7'/84°11.3'

35°36.1'/83°49.1'

35°36.4'/84°07.7'

35°36.7783°48.r

35°36.9'/84°06.7'

35°37.4'/84°06.7'

35°38.8'/83°48.3'

35°40.2'/83°43.r

35°40.2'/83°46.9'

35°41.0'/83°57.0'

35°41.5'/83°45.8'

35°42.1'/83°56.6'

35°44 f)'/83°53 7'

35°44 2'/83°49 4'

35°45.0'/84°01.0'

35°45.8'/84°07.3'

35°46.2'/84°07.8'

35°47.0783°59.0'

35°48.r/83°45.3'

35°48.8'/83°46.3'

35°49.5783°46.8'

35°52.4'/83°13.5'

35°52.7'/83°13.3'

35°53.0'/83°13.1'

36°10.9'/82°58.9'

35°04.0'/83°19.0'

35°55.7783°20.3'

35°58.0783°20.3'

35°58.3783°30.1'

35°58.3783°31.5'

35°58.4783°29.9'

35°58.5783°44.0'

35°34.3784°08.0'

35°43.5783°37.5'

35°43.8783°39.3'

35°49.5783°33.5'

35°49.7783°29.8'

35°50.0783°28.7'

35°50.7783°34.7'

35°53.5783°43.5'

35°53.9783°42.4'

35°54.5783°24.6'

35°55.0783°40.3'

Series

Lower

do.

do.

do.

do.

do.

do.

do.

Middle

do.

do.

Lower

Middle

do.

do.

Middle

do.

do.

do.

do.

do.

do.

do.

do.

do.

Middle

Lower

do.

Middle

do.

do.

Middle

do.

Lower

Middle

Lower

do.

Middle

do.

Lower

Middle

do.

do.

Stratigraphic unit

Knox Group

Jonesboro Limestone

do.

Chepultepec Dolomite

Mascot Dolomite

Whitesburg Limestone

Lenoir Limestone

do.

Jonesboro Limestone

Blockhouse Shale

Lenoir Limestone

do.

Arline Formation

Lenoir Limestone

do.

do.

do.

do.

do.

do.

Chepultepec Dolomite

Blockhouse Shale

Chepultepec Dolomite

do.

Lenoir Limestone

do.

Chepultepec Dolomite

Kingsport Dolomite

Lenoir Limestone

Chota Formation

Jonesboro Limestone

Lenoir Limestone

Mascot Dolomite

Jonesboro Limestone

Not known

Lenoir Limestone

Mascot Dolomite

Lenoir Limestone

do.

do.

CAI

value

3

3V2

3'/2

3

31/2

2V2

3

2V2

3

3

3

3

3i/2^t

3

3

2V2-3

3

2V2-3

2'/2-3

21/2-3

2W

3W^

3

3W

3V2-4

3-3V2

3V2

4

31/2

4

3-31/2

3V2^t

3

3

3

21/2-3

31/2

3V2

3-3 !/2

4

31/2^

3-3V2

3

2V2

3V2

3

thrust belt (Dumplin Valley thrust belt) of the Valley and 

Ridge closest to the Tuckaleechee Cove window were 

indexed at only two localities (fig. 2). In order to understand and explain the Tuckaleechee Cove window anomaly, 

additional CAI data were required. Ordovician rocks were 

sampled in all windows in the Great Smoky thrust sheet in 

central eastern Tennessee and at geologically appropriate 

spacings in the Dumplin Valley thrust belt.

Thirty new localities were sampled for CAI evaluation (table 1); except for a single locality at which Mississippian rocks were sampled, all were productive. The 29 

new localities in Lower and Middle Ordovician rocks 

increased the CAI data base in the Dumplin Valley thrust 

belt (between the southern limit of Blount County and 

northern Jefferson County) and the Calderwood, Cades 

Cove, Tuckaleechee Cove, and Wear Cove windows

Reevaluation of Conodont Color Alteration Patterns, Ordovician of Tennessee D5
(compare figs. 2 and 4). For consistency, we also reindexed 

the conodont collections used by Harris and others (1978) in 

their study for central eastern Tennessee; as a result, some 

earlier CAI values have been changed, chiefly because of 

changes in indexing methodology. Changes of one-half 

index in the eastern part of the Saltville and the western part 

of the Dumplin Valley thrust belts produced minor changes 

in the formerly consistent eastward increase in CAI values. 

The most significant change, however, is for rocks in the 

Tuckaleechee Cove window, now indexed as 3 (fig. 4), an 

increase of one index over the former value. The previous 

CAI value of 2 for rocks in this window (Epstein and others, 

1977; Harris and others, 1978) was based on a few 

relatively thin walled Middle Ordovician conodonts. Our 

experience has shown that such conodonts generally yield 

lower CAI values than do thicker walled conodonts in a 

sample. Lower and Middle Ordovician rocks at four localities in the Tuckaleechee Cove window all produced conodont collections having CAI values of 3, which are still 

lower than those from localities indexed by Harris and 

others (1978) in the nearby Dumplin Valley thrust belt to 

the west.

Ordovician rocks in the Cades Cove and Wear Cove 

windows (fig. 4) have CAI values of 3W, slightly higher 

than those of correlative strata in the Tuckaleechee Cove 

window. Ordovician rocks in the Calderwood window, 

about 20 km south of the Tuckaleechee Cove window, have 

intermediate CAI values of 3 to 3Vi. Thus, inspection of 

CAI values in the windows alone shows no apparent trend 

or relationship between CAI values and inferred tectonic or 

depositional patterns.

On the basis of seven CAI localities along a 120-kmlong strike belt of the Dumplin Valley thrust sheet, Harris 

and others (1978) showed that CAI values gradually 

decrease southwestward, northwestward, and northeastward from the eastern limit of the thrust belt in Sevier 

County. The 21 new localities in the Dumplin Valley thrust 

belt add complexity to the CAI patterns in this area 

(compare figs. 2 and 4), and some intriguing relationships 

emerge. The CAI values of 3Vi in Ordovician rocks of the 

Wear Cove and Cades Cove windows are opposite equivalent values in the Dumplin Valley thrust belt to the west. 

Likewise, the slightly lower CAI values in Ordovician rocks 

of the Tuckaleechee Cove window are opposite an area of 

similarly lower CAI in the Dumplin Valley thrust belt.

GEOLOGIC INTERPRETATION

We suspect that CAI patterns in lower Middle and 

Lower Ordovician rocks in the Dumplin Valley thrust belt 

and in windows to the east chiefly reflect primary depositional trends of Middle and Upper Ordovician predominantly clastic rocks that have been shown to be thickest in 

Blount and Sevier Counties and that may be even thicker in 

eastern Jefferson and Cocke Counties (fig. 5). The thickness of post-Lenoir Ordovician deposits in the eastern 

Valley and Ridge province of part of central eastern 

Tennessee was compiled from a variety of published reports 

(fig. 5). This task proved difficult because (1) Upper 

Ordovician rocks are partly eroded from the Saltville thrust 

belt and almost totally absent from the Dumplin Valley 

thrust belt, (2) Middle Ordovician clastic deposits are 

incompletely preserved or incompletely exposed in the 

Dumplin Valley thrust belt, and (3) the area of probable 

thickest pelitic deposition north of Sevierville is probably 

the most structurally complex area in the Dumplin Valley 

belt, so that thickness data are unavailable or speculative. 

Consequently, only generalized unrestored thicknesses 

could be plotted for post-Lenoir Middle Ordovician rocks 

south of Sevierville in the Dumplin Valley thrust belt and 

for post-Lenoir Middle Ordovician rocks and part of the 

Upper Ordovician rock succession in the Saltville thrust belt 

(fig. 5). Interestingly, these data mimic CAI trends in the 

same area. Moreover, these thickness trends appear to 

extend eastward toward the CAI values in the windows. 

This projection may be inappropriate, however, because 

Ordovician rocks in the windows are now 15 to 20 km east 

of correlative rocks in the Dumplin Valley thrust belt as a 

result of tectonic juxtaposition (fig. 3). In addition, palinspastic reconstructions based on existing interpretations 

(fig. 3) place these rocks at least 8 km farther eastward. 

Thus, it is likely that these parallel CAI trends, although 

possibly produced by the same processes, may not be part 

of a single depositional pattern.

CAI data from the single outcrop belt of younger 

Upper Devonian and Mississippian rocks in the Dumplin 

Valley thrust belt (fig. 1) would be useful, but, thus far, 

three samples from these dominantly clastic deposits have 

not produced conodonts. If CAI values for these younger 

rocks are considerably lower than those for the Lower and 

lower Middle Ordovician rocks that lie beneath the thick 

post-Lenoir Ordovician deposits in the same vicinity, then a 

primary depositional origin for the CAI patterns in the older 

Ordovician rocks could be established.

North of the Blount-Sevier County border in the 

Dumplin Valley thrust belt, CAI values are higher and 

appear to be more consistent. These higher values coincide 

with the broadening belt of Middle and Upper Ordovician 

chiefly clastic rocks in the same area (see Hardeman, 1966). 

Although thicknesses for these deposits are unavailable, the 

higher CAI values north of Blount County, as compared 

with those along strike to the south, strongly indicate 

thicker Ordovician deposits northward and eastward. We do 

not believe that these CAI trends are related to thickness 

patterns of post-Ordovician Paleozoic rocks or to major 

differences in thickness of tectonic overburden along strike.

D6 Evolution of Sedimentary Basins Appalachian Basin
n

o

o 

n.

o

n

o

TUCKALEECHEE 

COVE WINDOW 

 3 

30 KILOMETERS

Figure 4. Conodont color alteration index localities and revised isograds for Ordovician carbonate rocks e

Tennessee.
1

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0) CN -*T * 

C ^

co :^

^

c *; ^:

rt 03 O

O gj ' ' 

>~QJOC 

in "D "5

i- C </)

O

t 1-

o QJ

.ys D-C ,. 

2£§

U_ 0) ^

D8 Evolution of Sedimentary Basins Appalachian Basin
CONCLUSIONS

This study shows that:

1. The "anomalously" low CAI value for Ordovician 

rocks of the Tuckaleechee Cove window is not as low 

as that reported by earlier investigators (Epstein and 

others, 1977; Harris and others, 1978) and is anomalous only with respect to CAI values in correlative 

rocks northward and northeastward at the eastern limit 

of the Valley and Ridge province.

2. CAI patterns in Lower and lower Middle Ordovician 

rocks in central eastern Tennessee are more complex 

than those shown by earlier investigators; these patterns 

appear to be related chiefly to primary depositional 

trends in Middle and Upper Ordovician rocks.

3. CAI values in Ordovician rocks of the Tuckaleechee 

Cove window are slightly lower than those in correlative rocks in nearby windows. A similar pattern persists 

in correlative rocks in the Dumplin Valley thrust belt 

opposite the windows and appears to mimic thickness 

patterns of Middle and Upper Ordovician rocks in the 

same area. These depositional patterns may persist 

eastward toward the windows and could account for the 

difference in CAI values of rocks in the windows.

4. Regardless of these changes in CAI values and their 

inferred geologic causes, the data still indicate thermal 

potential for hydrocarbons in the eastward extension of 

Valley and Ridge rocks beneath the chiefly crystalline 

rocks of the Blue Ridge. Reevaluation of CAI patterns, 

however, somewhat decreases the area of this potential 

hydrocarbon province and virtually restricts its potential to natural gas.

More detailed sampling and mapping of CAI values 

will provide a higher resolution and probably increase the 

complexity of thermal maturation patterns in the Appalachian basin. Such studies may help to better understand the 

tectono-depositional framework of the basin, particularly 

along its eastern exposed margin, where such data can be 

projected into the eastward extension of the sedimentary 

succession beneath the Blue Ridge province.

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Bridge, J., 1956, Stratigraphy of the Mascot-Jefferson City zinc 

district, Tenn.: U.S. Geological Survey Professional Paper 

277, 76 p.

Bridge, J., and Hatcher, R.D., Jr., 1973, Geologic map of the 

New Market quadrangle, Tenn.: Tennessee Division of Geology Geologic Map GM 155-SE, scale 1:24,000.

Cattermole, J.M., 1955, Geology of the Shocks Gap quadrangle, 

Tenn.: U.S. Geological Survey Geologic Quadrangle Map 

GQ-76, scale 1:24,000.

 1958, Geology of the Knoxville quadrangle, Tenn.: U.S. 

Geological Survey Geologic Quadrangle Map GQ-115, scale 

1:24,000.

 1960, Geology of the Bearden quadrangle, Tenn.: U.S. 

Geological Survey Geologic Quadrangle Map GQ-126, scale 

1:24,000.

 1962, Geology of the Maryville quadrangle, Tenn.: U.S. 

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1:24,000. 

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Cook, F.A., Albaugh, D.S., Brown, L.D., Oliver, J.E., and 

Hatcher, R.D., Jr., 1979, Thin-skinned tectonics in the 

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no. 12, p. 563-567.

Cook, F.A., Brown, L.D., Kaufman, S., and Oliver, J.E., 1983, 

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color alteration; an index to organic metamorphism: U.S. 

Geological Survey Professional Paper 995, 27 p.

Hamilton, W., 1961, Geology of the Richardson Cove and Jones 

Cove quadrangles, Tenn.: U.S. Geological Survey Professional Paper 349-A, 55 p.

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Nashville, Tenn., Tennessee Division of Geology, scale 

1:250,000.

Harris, A.G., 1979, Conodont color alteration, an organo-mineral 

metamorphic index, and its application to Appalachian basin 

geology, in Scholle, P.A., and Schluger, P.R., eds., Aspects 

of diagenesis: Society of Economic Paleontologists and 

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the Appalachian orogen above a master decollement; a 

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Harris, L.D., Harris, A.G., deWitt, W., Jr., and Bayer, K.C., 

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4549, p. 980-982.

Keith, A., 1896a, Description of the Loudon sheet, Tenn.: U.S. 

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 1896b, Description of the Morristown sheet, Tenn.: U.S. 

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1:125,000.

Milici, R.C., Harris, L.D., and Statler, A.T., 1979, An interpretation of seismic cross sections in the Valley and Ridge of 

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Neuman, R.B., 1955, Middle Ordovician rocks of the TellicoSevier belt, eastern Tenn.: U.S. Geological Survey Professional Paper 274-F, p. F141-F178.

 1960, Geology of the Wild wood quadrangle, Tenn.: U.S. 

Geological Survey Geologic Quadrangle Map GQ-130, scale 

1:24,000.

References Cited D9
Neuman, R.B., and Wilson, R.L., 1960, Geology of the Blockhouse quadrangle, Tenn.: U.S. Geological Survey Geologic 

Quadrangle Map GQ-131, scale 1:24,000.

Nicoll, R.S., and Gorter, J.D., 1984, Interpretation of additional 

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and geothermal history of the Canning Basin, Western 

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Exploration Society of Australia Symposium, Perth, 1984, 

Proceedings, p. 411^25.

Roeder, D., Gilbert, O.E., and Witherspoon, W.D., 1978, 

Evolution and macroscopic structure of Valley and Ridge 

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Schultz, A.P., and Anders, D.E., 1985, Schurflingsfensters in the

Pulaski thrust sheet and their implications for hydrocarbon 

potential [abs.]: American Association of Petroleum Geologists Bulletin, v. 69, no. 9, p. 1447.

Swingle, G.D., Harper, D.D., Palmer, R.A., and Milici, R.C., 

1967, Geologic map of the Boyds Creek quadrangle, Tenn.: 

Tennessee Division of Geology Geologic Map 156-NW., 

scale 1:24,000.

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700-712.

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Studies in Geology 12, 64 p.

D10 Evolution of Sedimentary Basins Appalachian Basin ir US GOVERNMENT PRINTING OFFICE 1988 - 201-933 - 226/80023