M A R C H 3, 18 4 9

U.S. DEPARTMENT OF THE INTERIOR

Bedrock Geology of the 

Paducah 1°×2° CUSMAP Quadrangle,

Illinois, Indiana, Kentucky, and Missouri

By W. John Nelson

THE PADUCAH CUSMAP QUADRANGLE: RESOURCE AND TOPICAL INVESTIGATIONS

Martin B. Goldhaber, Project Coordinator

U.S. GEOLOGICAL SURVEY BULLETIN 2150–B

A joint study conducted in collaboration with the Illinois State Geological

Survey, the Indiana Geological Survey, the 

Kentucky Geological Survey, and the Missouri

Division of Geology and Land Survey

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1998
For sale by U.S. Geological Survey, Information Services

Box 25286, Federal Center

Denver, CO 80225

Any use of trade, product, or firm names in this publication is for descriptive purposes only and

does not imply endorsement by the U.S. Government

Library of Congress Cataloging-in-Publication Data

U.S. DEPARTMENT OF THE INTERIOR

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY

Mark Schaefer, Acting Director

Nelson, W. John

Bedrock geology of the Paducah 1°×2° CUSMAP Quadrangle, Illinois, Indiana, Kentucky, and Missouri / by W. John Nelson.

p. cm.—(U.S. Geological Survey bulletin ; 2150–B) (The Paducah CUSMAP

Quadrangle, resource and topical investigations ; B)

Includes bibliographical references.

Supt. of Docs. no. : I 19.3:2150–B

1. Geology—Middle West. I. Title. II. Series. III. Series: The Paducah 

CUSMAP Quadrangle, resource and topical investigations ; B

QE75.B9 no. 2150–B

[QE78.7]

[557.3 s—dc21 97–7724

[557.7] CIP
III

CONTENTS

Abstract ........................................................................................................................... B1

Introduction..................................................................................................................... 1

Regional Geologic Settings and Structural Overview .......................................... 1

Geologic History ............................................................................................................. 2

 Precambrian .......................................................................................................... 2

Sauk Sequence ...................................................................................................... 4

Rift-Fill Strata ................................................................................................. 4

Lamotte or Mount Simon Sandstone .............................................................. 5

Bonneterre or Eau Claire Formation............................................................... 5

Knox Group and Equivalent Rocks ................................................................ 5

Tippecanoe Sequence.............................................................................................. 8

Everton Formation .......................................................................................... 8

St. Peter Sandstone.......................................................................................... 11

Mohawkian Carbonates................................................................................... 11

Maquoketa Formation ..................................................................................... 11

Silurian Strata.................................................................................................. 12

Tamms Group of Rogers (1972) ..................................................................... 14

Kaskaskia Sequence................................................................................................ 14

Muscatatuck Group ......................................................................................... 16

New Albany Shale .......................................................................................... 16

Chouteau or Rockford Limestone ................................................................... 17

Valmeyeran Carbonate Bank .......................................................................... 17

Valmeyeran Deltaic Clastics........................................................................... 17

Valmeyeran Shelf Carbonates......................................................................... 18

Pope Group ..................................................................................................... 20

Absaroka Sequence................................................................................................. 20

Caseyville Formation ...................................................................................... 20

Tradewater Formation..................................................................................... 24

Carbondale Formation..................................................................................... 25

McLeansboro Group ....................................................................................... 25

Post-Pennsylvanian Tectonism ............................................................................... 26

Compressional Events..................................................................................... 26

Extensional Events.......................................................................................... 27

Zuni Sequence......................................................................................................... 27

Tejas Sequence........................................................................................................ 28

Post-Cretaceous Tectonism..................................................................................... 29

References Cited ............................................................................................................. 31

FIGURES

1–3. Maps showing:

 1. Structural setting of the Paducah 1°×2° quadrangle ......................................................................................... B3

2. Precambrian geology of the Paducah quadrangle and surrounding area.......................................................... 4

3. Structural features in the Paducah quadrangle ................................................................................................. 6

4–5. Generalized stratigraphic columns of:

4. Sauk sequence .................................................................................................................................................. 9

5. Tippecanoe sequence........................................................................................................................................ 10

 6. Structural development of the Ste. Genevieve fault zone, depicted by cross sections near where the 

fault zone crosses the Mississippi River ...................................................................................................................... 13
IV CONTENTS

PLATE

[Plate is in pocket]

1. Bedrock geologic map of the Paducah 1°×2°quadrangle

7. Generalized stratigraphic column of Kaskaskia sequence........................................................................................ 15

8–9. Cross sections depicting:

 8. Valmeyeran facies relationships in study area .............................................................................................. 18

9. Facies relationships in the lower part of the Pope Group in the Paducah quadrangle.................................. 21

10. Generalized stratigraphic column of Absaroka sequence ......................................................................................... 22

11. Map of Paducah quadrangle showing structures that were active during the Pennsylvanian Period ....................... 23

12. Diagram illustrating four episodes of tectonic activity involving the New Burnside anticline, McCormick

anticline, Lusk Creek fault zone, and Raum fault zone ............................................................................................ 24

13. Generalized stratigraphic column of the Zuni and Tejas sequences ......................................................................... 28

14–15. Map showing:

14. Faults that displace Cretaceous and younger strata within the Paducah quadrangle.................................... 30

 15. Marble Hill structure..................................................................................................................................... 31
B1

Bedrock Geology of the Paducah 1°×2°

Quadrangle, Illinois, Indiana, 

Kentucky, and Missouri

By W. John Nelson1

ABSTRACT

The Paducah 1°×2° quadrangle (hereafter referred to as

the Paducah quadrangle) encompasses the eastern flank of

the Ozark dome, the southern end of the Illinois Basin, and

the northern end of the Mississippi Embayment. Resting on

Proterozoic basement, sedimentary rocks of Cambrian

through Permian age in the Illinois Basin and Ozark dome

are overlapped by weakly lithified Cretaceous, Paleocene,

Eocene, and Pliocene strata in the embayment. This is one of

the most intensely faulted areas of the North American Midcontinent. A Proterozoic crustal terrane boundary (coincident with part of the Ste. Genevieve fault zone) and a failed

intracratonic rift (Reelfoot rift and Rough Creek graben)

have been reactivated repeatedly under various stress fields

from Proterozoic through late Tertiary times.

INTRODUCTION

The Paducah quadrangle encompasses some of the

most diverse and complex geology in the North American

Midcontinent. Overlying a Cambrian rift system, the Paducah quadrangle has undergone recurrent tectonic deformation throughout Phanerozoic time. Immediately to the south

is the New Madrid seismic zone, scene of the Midcontinent’s

most intense earthquake activity.

Ultramafic intrusive and explosive features, including

the enigmatic Hicks dome, are within the quadrangle. The

report area contains the largest fluorspar and tripoli deposits

in the United States and important resources of coal, petroleum, and limestone.

This report interprets the geologic history of the

Paducah quadrangle. It focuses on depositional and tectonic

evolution, particularly on tectonic events that influenced

sedimentation. Events are discussed in historical fashion,

1 Illinois State Geological Survey, Natural Resources Building, 615

East Peabody Drive, Champaign, IL 61820-6964.

applying the sequences of Sloss and others (1949) and

Sloss (1963). Another report (Nelson, 1995) emphasizes

map compilation, stratigraphic nomenclature, and correlation of units. That report also contains descriptions of map

units and structural features.

This work is a synthesis of previous mapping and

research combined with my own observations and interpretation. The bedrock geologic map (plate 1) was compiled

from published and unpublished geologic maps by dozens of

authors. Although some source maps date as far back as

1920, most of the area has been geologically mapped within

the last 25 years. My personal contribution includes mapping

(as sole author or coauthor) more than a dozen quadrangles

in southern Illinois. Also, I have conducted topical studies of

most of the major fault systems in the region along with

stratigraphic studies, mainly of Mississippian and Pennsylvanian rocks.

Synthetic mapping such as this yields a wealth of new

insights on depositional and tectonic history of the region. In

especially rapid flux are ideas on late Paleozoic sedimentation and on post-Cretaceous tectonism. Programs such as

CUSMAP (Conterminous United States Mineral Assessment Program) force State survey geologists to break the

constraints of State boundaries and politics. Many ideas

written herein will be obsolete by the time this is published.

The saying that “every geologic map is a progress report,”

was never more true than with this project.

REGIONAL GEOLOGIC SETTING AND 

STRUCTURAL OVERVIEW

The Paducah quadrangle lies in a tectonically unstable

part of the interior craton of North America. Portions of three

major structural provinces are within the quadrangle (fig. 1).

On the west, the Ozark dome was a persistent positive area

throughout Paleozoic time and stands as a plateau today.

Ordovician through Devonian strata, largely carbonates, dip

gently eastward and are transected by many northwest- and

northeast-trending fault zones. The southern part of the
B2 THE PADUCAH CUSMAP QUADRANGLE: RESOURCE AND TOPICAL INVESTIGATIONS

Illinois Basin, a “typical” interior cratonic basin (Leighton

and others, 1991), is in the central and eastern part of the

report area. Surface bedrock in the basin is mostly Mississippian and Pennsylvanian carbonate and siliciclastic rock. The

northern end of the Mississippi Embayment, an extension of

the Gulf Coastal Plain, extends into the Paducah quadrangle.

Weakly lithified Cretaceous and Tertiary siliciclastic strata

are found in the embayment.

Among structural features within the report area, several long-lived fault systems (fig. 1) controlled much of the

region’s geologic history. The Ste. Genevieve fault zone on

the northwest separates the Ozark dome from the Illinois

Basin and exhibits as much as 4,000 ft (1,200 m) of vertical

separation. The Ste. Genevieve may have originated along

the margin of a Proterozoic orogen (Heigold and Kolata,

1993). The fault zone was active during the Middle and Late

Ordovician (reverse faulting), Middle and Late Devonian

(normal faulting), Late Mississippian and Early Pennsylvanian (reverse faulting), and post-Pennsylvanian (reverse and

probably sinistral strike-slip faulting).

A dogleg-shaped Cambrian failed rift underlies the

southeastern part of the quadrangle. The rift comprises two

segments, the northeast-trending Reelfoot rift and the

east-trending Rough Creek graben (fig. 1). The Lusk Creek

fault zone and Rough Creek–Shawneetown fault system

mark the northwestern and northern margins of the rift, and

the Tabb and Pennyrile fault systems mark part of the southeastern and southern margins. The rift area subsided rapidly

throughout Paleozoic time, serving as a “depocenter” for the

Illinois Basin (Klein and Hsui, 1987; Kolata and Nelson,

1991a, 1991b). Boundary faults were reactivated periodically. Post-Pennsylvanian displacements along the Rough

Creek–Shawneetown split the Illinois Basin into two unequal

parts: the broad but shallow Fairfield Basin to the north and

the narrow but deep Eagle Valley–Moorman syncline to the

south. Repeated movements shattered the junction area; alkalic igneous activity produced Hicks dome, and fluorspar and

related minerals were emplaced. Beginning in Cretaceous

time, the Reelfoot rift area again subsided, forming the Mississippi Embayment. Northeast-trending faults were rejuvenated with dextral shear in and near the New Madrid seismic

zone.

GEOLOGIC HISTORY

PRECAMBRIAN

Most, if not all of the major structural features of the

Paducah quadrangle were established during the Precambrian Era. Precambrian events here are dimly known because

not a single Precambrian outcrop or borehole penetration

exists in the Paducah quadrangle. Nevertheless, significant

portions of the Precambrian history of the area can be reconstructed. That history is based on geophysical data,

especially published and industry seismic reflection profiles

and gravity and magnetic maps, and also on inferences drawn

from neighboring areas where Precambrian rocks crop out or

have been drilled.

Most boreholes that have reached Precambrian rocks

north of the Paducah quadrangle encountered granite and

rhyolite similar to that exposed in the St. Francois Mountains

of southeastern Missouri (Sargent, 1991a). The St. Francois

Mountains are part of the eastern granite-rhyolite province,

which ranges in age from approximately 1,480 to 1,380 Ma

(Kisvarsanyi, 1981; Bickford and others, 1986). In the past,

many geologists presumed that the entire Illinois Basin area

lay in the eastern granite-rhyolite province. That view has

been challenged by new interpretations based mainly on geophysical studies.

Sims and Peterman (1986) delineated the Central Plains

orogen, an Early Proterozoic fold belt that extends eastward

from northeastern Colorado across Kansas and Nebraska into

Missouri (fig. 2). The orogen is composed of metamorphic

(mainly amphibolite facies) and granitic rocks that range in

age from 1,800 to 1,630 Ma. Sims and Peterman did not

extend the orogen east of Missouri, but it may continue into

Illinois and may underlie part of the eastern granite-rhyolite

terrane. Xenoliths of biotite schist and biotite gneiss reportedly occur in a diatreme near Farmington, Mo., about 50 mi

(80 km) west of the Paducah quadrangle (Tarr and Keller,

1933). The xenoliths must have come from older rocks (Central Plains orogen?) underlying the granite and rhyolite,

which are near the surface at Farmington.

Published reflection seismic data (Sexton and others,

1986; Pratt and others, 1989; Heigold, 1991; Pratt and others,

1992) and proprietary seismic profiles show strong, coherent

Precambrian layering beneath a large area of Illinois, Indiana, and western Ohio. Pratt and others (1992) informally

named these layers the Centralia sequence. The Centralia

sequence underlies the northern part of the Paducah quadrangle and thickens northward. It extends to 11 mi (18 km)

below the surface in east-central Illinois (Heigold, 1991, p.

257–259), and is 4 to 8 mi (6 to 12 km) thick along the

COCORP seismic profile across southern Indiana and Illinois (Pratt and others, 1992). Downlap and truncation of layering suggest that the Centralia sequence may consist at least

partly of sedimentary rocks. Apparent grabens and half-grabens imply deposition in an extensional tectonic regime.

Because the Centralia sequence is either overlain by,

intruded by, or intercalated with rocks of the eastern granite-rhyolite province, the Centralia sequence can be no

younger than 1,480–1,380 Ma (Pratt and others, 1992).

The southern limit of the Centralia sequence coincides

with a region of higher Bouguer gravity and magnetic intensity values. Heigold and Kolata (1993) inferred a Proterozoic

crustal boundary separating layered Proterozoic rocks on the

north from denser, more magnetic, “altered lower crust” on

the south. The inferred boundary trends east-southeast from


BEDROCK GEOLOGY OF THE PADUCAH 1°×2° CUSMAP QUADRANGLE B5

modern East African rift has similar configuration (Kolata

and Nelson, 1992). 

Layered rocks below the Eau Claire Formation (Upper

Cambrian) attain a maximum thickness of more than 9,000

ft (2.7 km) in the Rough Creek graben at the east edge of the

Paducah quadrangle (Sargent, 1991b). The composition of

these rocks is little known because only a handful of wells

(none in the Paducah quadrangle) have penetrated them. East

of the quadrangle, a well in the Rough Creek graben in Grayson County, Kentucky, encountered a thick marine shale

succession beneath the Eau Claire. The shale contains thin

arkosic streaks and a few thin beds of oolitic limestone. A trilobite recovered from the shale indicated Middle Cambrian

age (Schwalb, 1982). The well did not reach crystalline basement.

LAMOTTE OR MOUNT SIMON SANDSTONE

Outside of the Reelfoot rift and Rough Creek graben,

the basal unit of the Sauk sequence is a transgressive sandstone called the Lamotte Sandstone in Missouri and the

Mount Simon Sandstone in Illinois and Kentucky. Deep

boreholes in the Paducah quadrangle partially penetrate this

unit, showing it to be fine- to coarse-grained, cross-bedded

sandstone, commonly arkosic near the base and becoming

more quartzose upward (Sargent, 1991a). The Lamotte or

Mount Simon thickens from less than 500 ft (150 m) at the

northwest corner of the Paducah quadrangle to about 3,000

ft (900 m) in southernmost Illinois (Sargent, 1991b). The

sandstone overlaps an irregular, hilly topography on granite-rhyolite “basement,” and is thin or absent overlying buried hills on the Precambrian surface. Within the rift, the

Mount Simon has not been differentiated from older layered

rocks.

BONNETERRE OR EAU CLAIRE FORMATION

The Bonneterre Formation is a unit of limestone and

dolomite overlying the Lamotte Sandstone on the Ozark

dome in Missouri, whereas the Eau Claire Formation is a

unit of thin-bedded, shaly, fossiliferous sandstone overlying

the Mount Simon in the subsurface in Kentucky and Illinois.

These two units are facies equivalents (Buschbach, 1975). In

the southeastern part of the Paducah quadrangle, the interval

is predominantly limestone, some of which is silty to sandy

and contains interbeds of calcareous shale and siltstone.

Northwestward, the interval becomes dolomitic, grading to

more than 80 percent dolomite at the northwest corner

(Sargent, 1991c). The siliciclastic content of the Bonneterre

or Eau Claire is greatest near the base and diminishes upward

(Treworgy and others, 1992; Sargent and others, 1992; Whitaker, Treworgy, and Noger, 1992; Whitaker, Treworgy,

Sargent, and Noger, 1992).

The Bonneterre or Eau Claire thickens from less than

500 ft (150 m) at the northwest corner of the quadrangle to

more than 1,800 ft (550 m) in northern Crittenden County,

Kentucky (Sargent, 1991d). The thick area corresponds with

the rapidly subsiding Rough Creek graben. By the time this

unit was deposited, active faulting had ceased in the graben.

The graben area continued to subside rapidly, however, as a

consequence of contraction of cooling igneous masses in the

lower crust and isostatic sinking of dense igneous rocks

(Klein and Hsui, 1987; Kolata and Nelson, 1991b).

KNOX GROUP AND EQUIVALENT ROCKS

Overlying the Bonneterre Dolomite or Eau Claire Formation is a thick succession of dolomite, more or less cherty

and sandy, ranging from Croixian (Late Cambrian) through

Canadian (Early Ordovician) age. Some authors also include

the Everton Formation (Whiterockian; Middle Ordovician)

in the Knox Group. On the outcrop in Missouri, these rocks

are divided into formations and no group name is used. The

term Knox Group is used in the subsurface of Illinois, Indiana, and Kentucky. Subdividing the Knox in the subsurface

is rather difficult; formation names used in the subsurface

differ from those used on the outcrop (fig. 4). The Knox is

equivalent lithologically and temporally to the Arbuckle

Group in Oklahoma and partially equivalent to the Ellenburger Group in Texas. Like their equivalents in neighboring

regions, Knox sediments were deposited in predominantly

shallow subtidal and peritidal environments on a vast shelf,

distant from sources of terrigenous clastics (Droste and

Shaver, 1983).

The Knox Group thickens from less than 2,000 ft (600

m) at the northwest corner of the Paducah quadrangle to

more than 8,000 ft (2,400 m) at the southeast corner (Sargent, 1991e). The rate of thickening is greatest in Perry

County, Missouri, near the Bodenschatz-Lick fault zone, and

in northern Jackson and Perry Counties, Illinois, near the Du

Quoin monocline. In the southeast part of the quadrangle, the

area of thickest Knox sediments coincides with the Reelfoot

rift and Rough Creek graben, denoting rapid subsidence of

these structures during Knox sedimentation.

The Davis Formation (Missouri) or Davis Member of

the Franconia Formation (Illinois) is one of the few units in

the Knox readily identifiable on wireline logs. It is a discontinuous unit of shale and shaly carbonate less than 100 ft (30

m) thick, contrasting with relatively pure carbonate rocks

above and below (Treworgy and others, 1992; Sargent and

others, 1992; Whitaker, Treworgy, and Noger, 1992; Whitaker, Treworgy, Sargent, and Noger, 1992). Because strong

velocity contrasts take place at both boundaries of the Davis,

the Davis produces strong seismic reflections and is a key

unit in interpreting seismic profiles (Heigold and Oltz,

1990).





BEDROCK GEOLOGY OF THE PADUCAH 1°×2° CUSMAP QUADRANGLE B11

the deep Illinois Basin, this contact is difficult to locate and

may be conformable (Kolata and Noger, 1991).

ST. PETER SANDSTONE

The St. Peter Sandstone is composed of nearly 100 percent well rounded, frosted quartz sand grains. The St. Peter

varies from 0 to 210 ft (64 m) thick in outcrops; available

well records show the sandstone to be 100 to 120 ft (30 to 37

m) thick in the northern part of the quadrangle and also near

Cairo, Ill. Elsewhere in the Paducah quadrangle the St. Peter

is generally 50 to 100 ft (15 to 30 m) thick (Sargent, 1990b).

Tectonic influence on St. Peter deposition in the study area

cannot be demonstrated.

The St. Peter is a transgressive, nearshore to shallow

subtidal deposit. Its sand was derived from Cambrian and

Proterozoic sandstones to the north. Age of the St. Peter is

early Mohawkian (Thompson, 1991) or, using different terminology, Chazyan to early Blackriveran (Shaver, 1985).

MOHAWKIAN CARBONATES

Overlying the St. Peter Sandstone is a succession of

Middle Ordovician carbonate formations: the Dutchtown

Formation (oldest), Joachim Dolomite, Pecatonica(?) Formation, Plattin Formation, Decorah Formation, and

Kimmswick Limestone. An isopach map by Sargent (1990c)

shows that these rocks thicken from less than 700 ft (210 m)

at the northwest corner of the Paducah quadrangle to 1,450

ft (440 m) in northern Pope County, Illinois. Mohawkian

carbonates are thickest along a belt that runs northeast from

southern Pulaski County to Pope County, following the

northwest margin of the Reelfoot rift.

The Dutchtown Formation is dark-colored, micritic,

silty to sandy limestone interbedded with lesser amounts of

dolomite. The rock contains bitumen-filled vugs and emits a

petroliferous odor when hammered. The Dutchtown thins

northward from 180 ft (55 m) in southern Cape Girardeau

County to less than 20 ft (6 m) in Perry County, Missouri.

The Dutchtown is interpreted as supratidal to peritidal

deposits (Kolata and Noger, 1991).

The Joachim Dolomite is lighter colored than the

Dutchtown and consists primarily of micritic to finely crystalline dolomite, with thin interbeds of sandstone and shale.

Gypsum and anhydrite beds (in subsurface), along with mud

cracks, ripple marks, and sparse fauna, suggest that the

Joachim was deposited in sabkha environments (Okhravi

and Carozzi, 1983). The Joachim thins northwestward from

280 to 135 ft (85 to 40 m) along the outcrop in Missouri. The

Dutchtown and Joachim are difficult to differentiate in the

subsurface; limestone and dolomite intertongue in variable

fashion, generally becoming shalier toward the base (Treworgy and others, 1992). The combined Dutchtown and

Joachim are more than 600 ft (183 m) thick in extreme southeastern Illinois within the Reelfoot rift (Willman and others,

1975, p. 63).

The Pecatonica(?) and Plattin Formations are lithologically similar units that are separable only in optimal

exposures, such as roadcuts and quarry walls. Thompson

(1991, p. 109) stated that, for this reason, use of the name

Pecatonica in Missouri has a “tentative and questionable

future.” Kolata and Noger (1991) reported that the Pecatonica and Plattin can be differentiated in subsurface by use of

electric and gamma-ray logs. The difference must reflect

subtle lithologic changes that are not readily apparent in outcrops. Some geologists who mapped 71/2-minute geologic

quadrangles in Missouri distinguished the Pecatonica, but

they did not do so in a consistent fashion (Nelson 1995).

Thompson (1991) refers to the Plattin as a group, but I

consider it a formation because no formational units within

the Plattin have been mapped within the Paducah quadrangle

(Nelson, 1995; Nelson and others, 1995). The Plattin and

Pecatonica(?) were combined with the Decorah Formation

into a single unit on the map that accompanies this report

(plate 1).

The Pecatonica(?) and Plattin are composed of laminated and burrowed, brownish-gray micritic dolomite and

limestone (lime mudstone). Mud cracks, algal mats, intraformational breccias, and sparse fauna point to deposition in

tidal flats and shallow lagoons (Kolata and Noger, 1991).

The Platteville Group (Pecatonica(?) and Plattin) thickens

southeastward from 350 ft (107 m) from the northwest corner to more than 600 ft (183 m) in the southeast part of the

Paducah quadrangle (Willman and others, 1975, p. 66).

The Decorah Formation (Rocklandian age) thins from

about 35 ft (10 m) in the northwestern part of the study area

to a feather-edge in the central part. The Decorah is composed of thin-bedded, argillaceous, highly fossiliferous

limestone intercalated with greenish-gray calcareous shale.

It is the distal edge of a clastic wedge derived from the

Transcontinental arch far to the northwest (Kolata and

Noger, 1991). The upper contact is disconformable.

The Kimmswick Limestone is a distinctive unit of

white to light-gray and pink, medium- to coarse-grained,

cross-bedded crinoidal grainstone that is quarried as a source

of high-calcium limestone. The Kimmswick outcrop belt

curves southward through eastern Perry County, Missouri,

into Alexander County, Illinois, along the Mississippi River.

Thickness of the Kimmswick is typically 110 to 165 ft (35 to

50 m); no regional thickness trends are apparent in the study

area. Apparently, the rift had little influence on Kimmswick

sedimentation. The Kimmswick was deposited on a shallow,

open-marine shelf, well agitated by waves and currents. The

upper contact is a pronounced unconformity, which accounts

for much of the local thickness variation.

A thin, lenticular unit of darker, finer grained, more

argillaceous limestone, the Cape Limestone, locally overlies

the Kimmswick.
B12 THE PADUCAH CUSMAP QUADRANGLE: RESOURCE AND TOPICAL INVESTIGATIONS

MAQUOKETA FORMATION

Cincinnatian siliciclastic strata of the Paducah quadrangle are assigned to the Maquoketa Formation. Although

previously ranked as a group by some geologists (Thompson

1991; Nelson 1995), the Maquoketa is classified as a formation here because the smaller units that comprise it are not

mappable at scales of 1:24,000 or smaller (Nelson and others,

1995).

In most of the quadrangle, the Maquoketa is composed

of dark-gray to greenish-gray, partly silty and calcareous

shale with thin limestone interbeds. Isopach mapping by Sargent and Roemelle (1990) and Whitaker (1988) shows the

Maquoketa regionally thickening eastward from about 150 ft

(45 m) to more than 300 ft (90 m). Eastward thickening

reflects provenance of most Maquoketa sediment from the

Taconic orogenic belt in the Northeastern United States. The

Maquoketa locally thickens in extreme western Kentucky

(Whitaker, 1988), suggesting accelerated subsidence of the

Reelfoot rift.

In the southwestern part of the Paducah quadrangle, the

Maquoketa is divisible into four members (Thompson, 1991;

Nelson, Devera, and Masters, 1995). The Cape La Croix

Shale Member at the base is dark-gray, marine clay shale that

contains thin interbeds of micritic limestone. The Cape La

Croix becomes silty near the top and grades into the overlying Thebes Sandstone Member. The Thebes is more than 100

ft (30 m) thick in places and is composed of calcareous siltstone and very fine grained, argillaceous sandstone, much of

it intensively burrowed. Red and green variegated claystone

occurs at the top of the Thebes in some places. Above the

Thebes is the Orchard Creek Shale Member, which, like the

Cape La Croix, consists of dark-gray marine shale containing

micritic limestone interbeds. The Orchard Creek grades into

the overlying Girardeau Limestone Member. Eastward and

northward into the subsurface the Thebes and Girardeau

grade to shale (Maquoketa Shale undivided).

Evidently, part of the Ozark dome was subaerially

exposed during Cincinnatian time, providing a local source

of sediment for the Thebes Sandstone Member. The

Girardeau Limestone Member probably accumulated in relatively shallow water on the flank of the dome. Two shoaling-upward sequences are evident in the Maquoketa. The

first comprises the Cape La Croix and Thebes; the second the

Orchard Creek and Girardeau.

Both the Kimmswick Limestone and the Maquoketa

Formation thin abruptly on the southwest side of the Ste.

Genevieve fault zone in Perry County, Missouri, and adjacent Jackson County, Illinois (fig. 6). The Kimmswick is 50

to 100 ft (15 to 30 m) thick southwest of the fault zone in the

Altenburg (Amos, 1985a) and Neelys Landing (Whitfield

and Middendorf, 1989) quadrangles and in a well southwest

of the fault in southwestern Jackson County, Illinois. These

thicknesses compare to 135 to 165 ft (40 to 50 m) in wells

drilled a short distance northeast of the fault zone. Moreover,

the Kimmswick is locally dolomitized southwest of the fault

zone (Amos, 1985a, 1985b, 1986a; D.R. Kolata, oral commun., 1992). The Maquoketa thickens from 60 to 100 ft (18

to 30 m) southwest of the fault zone to 130 to 165 ft (40 to 50

m) northeast of the fault (Amos, 1985a, 1986b). Thickness

changes appear to affect all the members of the Maquoketa

proportionately. Evidently, the southwest side of the Ste.

Genevieve fault zone was progressively uplifted during deposition of the Kimmswick and Maquoketa.

The upper surface of the Maquoketa is a disconformity.

The thin, discontinuous Leemon Formation (formerly

mapped as the Edgewood Formation) locally overlies the

Maquoketa near Cape Girardeau. The Leemon is oolitic and

skeletal limestone of latest Ordovician age (Thompson and

Satterfield, 1975).

SILURIAN STRATA

Disconformably overlying the Maquoketa Formation

(or the Leemon Formation, where present) is the Alexandrian

(Lower Silurian) Sexton Creek Limestone. This is a unit of

cherty, dense, micritic, wavy-bedded limestone that thickens

from 15 to 65 ft (5 to 20 m) in outcrop belt near the Mississippi River to more than 125 ft (38 m) in the subsurface in

Franklin County, Illinois (Willman and others, 1975, p. 96).

The upper contact of the Sexton Creek is disconformable.

Overlying the Sexton Creek is the Bainbridge Formation, divided into the older St. Clair Limestone Member and

the younger Moccasin Springs Member (Thompson, 1993;

Nelson, Devera, and Masters, 1995). The St. Clair is gray

lime mudstone to wackestone that is mottled in red and green

and contains red echinoderm fragments, ostracods, and foraminifera. It thickens from 5 to 30 ft (2 to 9 m) on the outcrop

to about 60 ft (18 m) in the subsurface in the southeast part

of the quadrangle (Ross, 1964). The Moccasin Springs is

composed of argillaceous to silty lime mudstone intercalated

with calcareous shale and siltstone, all of which are

Figure 6 (facing page). Structural development of the Ste.

Genevieve fault zone, depicted by cross sections near where the

fault zone crosses the Mississippi River. A, Rattlesnake Ferry fault

undergoes reverse displacement, with southwest block upthrown,

in Cincinnatian time. Kimmswick Limestone on upthrown block is

thinned and dolomitized; Maquoketa Formation is thinned. B,

Pomona fault undergoes normal displacement in late Middle to

Late Devonian time. Devonian rocks are eroded from the upthrown

northern block while syntectonic sandstone and conglomerate are

deposited along the base of the fault scarp in the St. Laurent Formation. By end of Devonian Period (as depicted here), fault activity

was waning and thin New Albany Shale was deposited northeast of

the fault. The Rattlesnake Ferry fault, southwest of the Pomona

fault, was inactive during the Devonian. C, Both Rattlesnake Ferry

and Pomona faults undergo reverse displacement during Morrowan

(Early Pennsylvanian) time. The result is an angular unconformity

between Mississippian and Pennsylvanian rocks and syntectonic

conglomerates in Morrowan sediments near the fault zone.

B14 THE PADUCAH CUSMAP QUADRANGLE: RESOURCE AND TOPICAL INVESTIGATIONS

variegated in shades of red, green, and gray. The Moccasin

Springs is 60 to 140 ft (18 to 43 m) thick in outcrop, and

thickens to 250 to 300 ft (80 to 100 m) in parts of Pulaski and

Massac Counties, Illinois, and the adjacent part of Kentucky.

This area lies within the Reelfoot rift.

Depositional environments of Silurian rocks in the Paducah quadrangle have not been studied much. The Sexton

Creek, St. Clair, and Moccasin Springs all were deposited in

relatively quiet, but not necessarily deep, marine water. Red

and green colors in the Moccasin Springs may reflect colors

of source sediments from southwest of the area (Becker and

Droste, 1978). Equivalent lighter colored carbonate sands

were deposited in shallow reef-forming environments north

of the Paducah quadrangle. Authors disagree on whether the

reefs grew along a distinct shelf-slope margin (Becker and

Droste, 1978; Droste and Shaver, 1980, 1987; Mikulic,

1991), or along a gradual south-sloping ramp (Whitaker,

1988).

The upper contact of the Bainbridge is reported to be

disconformable near the Ste. Genevieve fault zone in Perry

and Ste. Genevieve Counties, Missouri (Amos, 1985a,

1985b, 1986a). Elsewhere, this contact appears to be conformable (Pryor and Ross, 1962; Ross 1963; Becker and

Droste, 1978; Droste and Shaver, 1987). 

TAMMS GROUP OF ROGERS (1972)

The name Tamms group was used in a thesis by Rogers

(1972) for the interval of cherty carbonate rocks and bedded

chert that overlies the Bainbridge Formation and extends to

the top of the Tippecanoe sequence. The group includes four

formations: Bailey Limestone (oldest), Grassy Knob Chert,

Backbone Limestone (Illinois) or Little Saline Limestone

(Missouri), and Clear Creek Formation.

The Tamms group of Rogers (1972) crops out in western Alexander and Union Counties, Illinois, eastern Cape

Girardeau and Perry Counties, Missouri, and in fault blocks

within the Ste. Genevieve fault zone. Deep surficial weathering, extensive silicification, lack of marker beds, scarcity of

easily extracted fossils, and poor exposures hamper study of

these rocks. Formations have been mapped inconsistently by

various geologists.

The Bailey Limestone is composed of light olive gray,

argillaceous to silty, cherty lime mudstone, with thin interbeds of greenish-gray shale in the lower part. Upper and

lower contacts are gradational. The Bailey is approximately

250 to 400 ft (75 to 120 m) thick. Sparse fossil evidence indicates that the lower part of the Bailey is of Late Silurian

(Cayugan) age (Becker and Droste, 1978), whereas the upper

part is Early Devonian (Collinson and others, 1967).

The Grassy Knob Chert is largely thick-bedded, tripolitic to novaculitic, burrowed chert in outcrop; it contains

beds of siliceous limestone and dolomite in the subsurface.

The Grassy Knob generally thickens southward in the outcrop belt from about 165 to 300 ft (50 to 90 m).

The Backbone Limestone (Illinois) or Little Saline

Limestone (Missouri) is a unit of white to light-gray,

high-calcium, coarse skeletal grainstone. The limestone is as

thick as 200 ft (60 m) on the north and pinches out southward. Lenses of limestone of similar lithology occur at various positions within the Tamms group of Rogers (1972) in

the subsurface.

The Clear Creek Formation is light gray, siliceous,

cherty, mostly thin-bedded and micritic limestone that contains common brachiopods and trilobites. It thickens southeastward from an erosional feather-edge in the northwestern

Paducah quadrangle to at least 650 ft (200 m) in the Reelfoot

rift area (Droste and Shaver, 1987, p. 12). In much of the outcrop belt in Illinois, the Clear Creek is altered to microcrystalline silica (tripoli), the purest beds of which are mined

commercially.

The Bailey and Grassy Knob probably were deposited

in a sea that gradually deepened. The Backbone or Little

Saline Limestone is a high-energy deposit that accumulated

in shoal areas bordering the proto-Illinois Basin. The Clear

Creek Formation represents deposition in relatively shallow,

but quiet, marine waters. Primary silica in the Tamms group

of Rogers (1972) is partly biogenic, produced by organisms

such as sponges, and partly detrital (Nelson, Devera, and

Masters, 1995).

The unconformity at the top of the Tippecanoe sequence

is well-marked only in the northwest part of the Paducah

quadrangle. The Grand Tower Limestone (Kaskaskia

sequence) directly overlies the Little Saline Limestone in

part of Ste. Genevieve County, Missouri (Weller and St.

Clair, 1928). Silurian rocks may directly underlie the

Kaskaskia sequence at the northwest corner of the Paducah

quadrangle (Willman and others, 1967). But in the deepest

part of the Illinois Basin, near the common corner of Indiana,

Illinois, and Kentucky, sedimentation was continuous from

Early Devonian into Middle Devonian time (Devera and

Fraunfelter, 1988).

KASKASKIA SEQUENCE

The informally named Kaskaskia sequence of Sloss and

others (1949) and Sloss (1963) comprises strata that range

from Middle Devonian through Late Mississippian (Chesterian) age (fig. 7). The sequence is mostly limestone, except

for the Devonian and Mississippian New Albany Shale and

Chesterian mixed carbonates and siliciclastics.

Figure 7 (facing page). Generalized stratigraphic column of

Kaskaskia sequence. Kind., Kinderhookian. Letter symbols: FG,

Fern Glen Formation; Bu, Burlington Limestone; K, Keokuk Limestone; W, Warsaw Formation; Bo, Borden Siltstone; S, Springville

Shale; FP, Fort Payne Formation; U, Ullin Limestone. Due to space

limitations, not all named formations can be shown. See figure 8 for

more detail of Valmeyeran units and figure 9 for more detail of Pope

Group.

B16 THE PADUCAH CUSMAP QUADRANGLE: RESOURCE AND TOPICAL INVESTIGATIONS

MUSCATATUCK GROUP

The Muscatatuck Group in the Paducah quadrangle

comprises the Grand Tower or Jeffersonville Limestone and

the St. Laurent or Sellersburg Formation (Shaver, 1985; Nelson, 1995). The group crops out in a narrow strip in Union

and Alexander Counties, Illinois, and in fault slices along the

Ste. Genevieve fault zone in Missouri.

The Grand Tower (Missouri and Illinois) or Jeffersonville (Kentucky and Indiana) Limestone is commonly

regarded as early Middle Devonian (Eifelian). However, at

least locally, the lower part contains late Early Devonian

(Emsian) fossils (Boucot and Johnson, 1968; Devera and

Fraunfelter, 1988).

The Dutch Creek Sandstone Member at the base of both

formations is a lenticular unit composed of well-rounded,

frosted quartz sand (Meents and Swann, 1965). The Dutch

Creek is best developed on the flank of the Ozark dome. Its

sand probably was derived from the St. Peter Sandstone and

older Paleozoic sandstones exposed on the dome. Fossils,

taphonomy, and sedimentology indicate that the Dutch Creek

was distributed by tidal currents. The remainder of the Grand

Tower and Jeffersonville is largely skeletal grainstone with

floating sand grains, probably windblown. Patch reefs occur

in the middle Grand Tower and Jeffersonville. The upper part

of the limestone is more micritic and contains tempestites.

Overall, the Grand Tower reflects sedimentation in seawater

of normal salinity and oxygen content in depths ranging from

shallow subtidal to below fair-weather wave base (Devera

and Fraunfelter, 1988).

The Grand Tower or Jeffersonville is thickest (more

than 240 ft; 73 m) in an east-trending belt immediately south

of the Rough Creek–Shawneetown fault system. Evidently

normal, down-to-the-south displacements took place along

the Rough Creek during Eifelian sedimentation (Freeman,

1951). The Grand Tower thins to less than 20 ft (6 m) on the

flank of the Ozark dome in Alexander County, southernmost

Illinois (Nelson and others, 1995). In that area, only the

Dutch Creek Sandstone Member is present; it onlaps older

strata.

The upper part of the Muscatatuck Group comprises the

St. Laurent Formation (Missouri and Illinois) and the Sellersburg Limestone (Kentucky). The Lingle and Alto Formations, previously used in Illinois, have been abandoned in

favor of the St. Laurent Formation because the Lingle and

Alto were inadequately defined and are not mappable (Nelson, Devera, and Masters, 1995). The St. Laurent and Sellersburg are similar in lithology: argillaceous limestone and

dolomite, which is darker and more micritic than that of the

Grand Tower or Jeffersonville, interbedded in some areas

with shale, siltstone, sandstone, and conglomerate. The St.

Laurent is more than 200 ft (60 m) thick along the Ste.

Genevieve fault zone and ranges up to about 110 ft (35 m)

thick south of the Rough Creek–Shawneetown fault system

(North, 1969). These areas of thickened strata reflect

contemporaneous movements along faults. Elsewhere in the

Paducah quadrangle, the St. Laurent or Sellersburg is generally less than 100 ft (30 m) thick. Carbonate rocks thin westward and intertongue with shale and siltstone in Union and

Alexander Counties, southwestern Illinois (Nelson, Devera,

and Masters, 1995). Farther east in the subsurface, the upper

part of the St. Laurent intertongues with the overlying New

Albany Shale (North, 1969; Cluff and others, 1981).

The Ste. Genevieve fault zone was active from Givetian

time to nearly the end of the Devonian Period. The active

faults lay along the northern border of the zone and extended

from west of the study area through Missouri into western

Jackson County, Illinois. The northern (Sparta shelf) block

was raised as much as 1,000 ft (300 m) and deeply eroded

prior to Mississippian sedimentation. North of the fault zone,

Mississippian rocks unconformably overlie units as old as

Late Ordovician; south of the fault, the complete Devonian

and Silurian section is preserved (fig. 6). Syntectonic deposits of quartz sandstone and conglomerate containing clasts of

older formations occur in the St. Laurent Formation south of

the active Devonian fault in Missouri (Weller and St. Clair,

1928; Croneis, 1944; Nelson and Lumm, 1985).

Meents and Swann (1965) proposed that a deep

fault-bounded trench called the Wittenberg trough lay along

the Ste. Genevieve fault zone during Middle Devonian time.

Other studies, however, do not support existence of such a

trough. The Grand Tower Limestone and St. Laurent Formation contain patch reefs and other sedimentary features characteristic of shallow subtidal deposition in the area of the

“Wittenberg trough” (Devera and Fraunfelter, 1988). The

narrow strip of Devonian outcrops along the fault zone is the

product of a reversal of displacement. During Middle and

Late Devonian time, shallow marine sediments were deposited south of the active fault, while the crustal block north of

the fault was upthrown and eroded. Then, in Late Mississippian and Pennsylvanian time, faults near the southern margin

of the Ste. Genevieve fault zone underwent reverse displacement, with the southern (Ozark dome) block uplifted (fig. 6).

The younger faults were located a few miles south of and parallel to the older faults. Silurian and Devonian rocks were

eroded south of the fault zone and were preserved only in the

narrow strip between the older (northern) and younger

(southern) strands of the Ste. Genevieve fault zone (Weller

and St. Clair, 1928; Nelson and Lumm, 1985; Devera and

Fraunfelter, 1988).

NEW ALBANY SHALE

Overlying the Muscatatuck Group is the New Albany

Shale. The New Albany previously was classified as a group

in Illinois, but Nelson (1995) reduced it to a formation

because its subdivisions do not meet the test of mappability.

The New Albany is part of the body of Upper Devonian black

shale, which, under many names (Chattanooga Shale,
BEDROCK GEOLOGY OF THE PADUCAH 1°×2° CUSMAP QUADRANGLE B17

Woodford Shale, Ohio Shale, Bakken Formation, etc.), covers much of the North American craton. The New Albany is

mostly of Frasnian and Famennian age, but it includes

Givetian (Middle Devonian) beds at the base and Kinderhookian (Lower Mississippian) beds at the top.

The New Albany reaches a maximum thickness of more

than 460 ft (140 m) in Hardin County, Illinois, and the adjacent part of Kentucky (Cluff and others, 1981). Continuing a

familiar pattern, the New Albany is thickest near the western

end of the Rough Creek graben. Thickness changes of the

New Albany east of the report area (Schwalb and Potter,

1978) demonstrate that both the northern (Rough Creek) and

southern (Pennyrile) boundary faults of the graben underwent normal displacements concurrent with New Albany

sedimentation. In and near the subsiding graben, the New

Albany is conformable and intertongues with underlying

carbonates (North, 1969). The New Albany rests disconformably on carbonate rocks of the Muscatatuck Group in

outcrops along the flank the Ozark dome in southern Illinois

(Nelson and others, 1995). On the Sparta shelf, north of the

Ste. Genevieve fault zone, the New Albany is thin and lenticular, and it disconformably lies on rocks as old as Ordovician. Uplift of the southern margin of the shelf thus was

winding down by the end of Devonian time.

The New Albany is a unit of dark-gray to black, fissile,

phosphatic, organic-rich shale, interbedded in part with less

fissile and organic-rich, mottled, greenish to olive-gray

shales. Fossils include fish remains, small brachiopods, conodonts, the “spore” Tasmanites, and a variety of trace fossils.

Deposition in quiet water under dysaerobic to anaerobic conditions is implied (Cluff and others, 1981).

CHOUTEAU OR ROCKFORD LIMESTONE

The thin but widely persistent Chouteau (Missouri and

Illinois) or Rockford (Kentucky) Limestone overlies the

New Albany Shale in much of the report area. Too thin to

map separately, the Chouteau or Rockford was combined

with either the New Albany or the overlying Springville

Shale and Fort Payne Formation by various map authors.

The discrepancy is insignificant at the scale of plate 1.

The Chouteau or Rockford is composed of argillaceous

to silty lime mudstone that contains scattered fossil fragments, including echinoderms, goniatites, conodonts, and

foraminifera. Maximum thickness is about 8 ft (2.4 m). Conodont faunas indicate Kinderhookian (Early Mississippian)

age (Collinson and Scott, 1958). Phosphatic nodules in the

Chouteau, a faunal gap, and a weathering profile at the top of

the New Albany imply a disconformity at the base of the

Chouteau in outcrops of southwestern Illinois (David

Macke, written commun., 1992). The Chouteau or Rockford

was deposited in quiet water on a sea floor having little relief

(Sable and Dever, 1990).

VALMEYERAN CARBONATE BANK

Valmeyeran (Middle Mississippian) strata of the report

area represent three facies assemblages: (l) a lower Valmeyeran carbonate bank in the northwestern part of the quadrangle, (2) deltaic siliciclastics partly equivalent to and partly

overlapping the carbonate bank, and (3) upper Valmeyeran

shelf carbonates that overlie the deltaic clastics (fig. 8).

Carbonate-bank strata (map symbol Mkb) crop out

in small fault slices along the Ste. Genevieve fault zone

in Missouri and occur in the subsurface on the western

Sparta shelf in Illinois. Constituent units are the Fern

Glen Formation (oldest), Burlington Limestone, and

Keokuk Limestone. The Fern Glen is composed of fossiliferous, cherty limestone that contains interbeds of red

and green shale, especially near the base. The Burlington

and Keokuk Limestones are both light-colored, largely

crinoidal limestones that contain abundant chert layers

and nodules. Aggregate thicknesses of these three units

range from about 250 to 400 ft (75 to 120 m).

VALMEYERAN DELTAIC CLASTICS

While the carbonate bank developed on the Sparta

shelf, a delta (Borden delta) prograded into the Illinois Basin

from the east. Deltaic clastics are assigned to three formations in the study area: the Springville or New Providence

Shale, the Borden Siltstone, and the Warsaw Formation.

The Springville (Illinois) or New Providence Shale

(Kentucky) consists of prodeltaic clay shale, silty shale, and

siltstone that form an upward-coarsening interval 5 to 60 ft

(1.5 to 18 m) thick. The Springville crops out in Union and

Alexander Counties, Illinois, where it lies conformably on

the Chouteau Limestone or unconformably on older units

(Nelson and others, 1995). The Springville also crops out at

Hicks dome in southeastern Illinois; the New Providence

crops out in fault slices in western Kentucky. This unit

underlies the entire eastern half of the report area in the subsurface.

Delta-front deposits of the Borden Siltstone occurs in

the subsurface in northern Jackson and adjacent counties,

Illinois. Well records indicate a succession of calcareous,

glauconitic silty mudstone, siltstone, and fine-grained sandstone as thick as 290 ft (88 m) (Lineback, 1966, 1981). The

Borden is a lateral equivalent of the Springville and lies east

of the carbonate-bank rocks (Lineback, 1966).

The Warsaw Formation is equivalent to the upper part

of the Borden and overlaps the carbonate bank near the

northwest corner of the Paducah quadrangle. The Warsaw is

a unit of intercalated gray calcareous shale and oolitic and

skeletal limestones.

Swann and others (1965) and Lineback (1966, 1969,

1981) envisioned the carbonate bank as having a steep margin that stood 200 to 300 ft (60 to 90 m) above the floor of a

BEDROCK GEOLOGY OF THE PADUCAH 1°×2° CUSMAP QUADRANGLE B19

Ullin–Fort Payne contact as sharp, this contact is gradational

and intertonguing (Cluff and Lineback, 1981, p. 38; Lasemi

and others, 1994; Nelson and others, 1995). Lineback (1966,

1969, 1981) and Cluff and Lineback (1981) interpreted the

Ullin as a deep-water deposit that largely filled a “starved

basin” that developed seaward from the Borden delta. Cluff

and Lineback (1981, p. 38) further proposed that the Ullin

was deposited in water 300 ft (90 m) or deeper. These interpretations are questioned on the basis of new research.

Lasemi and others (1994) identified Waulsortian mounds in

the lower part of the Ullin and “Warsaw.” These mounds

coalesced laterally and vertically, forming several large carbonate banks surrounded by deeper water where the Fort

Payne was deposited. The sea gradually shallowed;

cross-bedded grainstone of the upper part of the Ullin and

“Warsaw” was deposited in well-agitated water above storm

wave base (Sable and Dever, 1990; Lasemi and others,

1994).

The Salem Limestone comprises carbonate rocks of

widely varying textures overlying the Ullin Limestone and

equivalent units. Salem lithologies include light-colored

oolitic and skeletal grainstones, intercalated with darker

packstones, wackestones, and lime mudstones. Nearly black,

petroliferous lime mudstone has been mapped in the Salem

in the Illinois portion of the fluorspar district. The Salem is

generally characterized by presence of oolites and endothyrid foraminifera (sparse or absent in enclosing units) and

scarcity of dolomite and chert. Both upper and lower contacts of the Salem are gradational and intertonguing (Lineback, 1972; Cluff and Lineback, 1981). Placement of these

contacts differs markedly among different geologists, particularly across the Illinois-Kentucky State line (Nelson, 1995).

Thickness trends of the Salem are difficult to assess

because of varying definitions of the unit. It is thinnest, 105

to 175 ft (36 to 55 m) thick, in the northwestern corner of the

quadrangle and reportedly reaches 500 ft (152 m) in White

County, Illinois (Cluff and Lineback, 1981), and in parts of

Hardin and adjacent counties, southeastern Illinois (Baxter

and others, 1963, 1967; Baxter and Desborough, 1965). In

adjacent parts of Kentucky, however, much of the interval

assigned to the Salem in Illinois was mapped as “Warsaw”

and St. Louis Limestones.

The Salem evidently reflects shallow marine sedimentation. Cluff and Lineback (1981) recognized three to four

shoaling-upward cycles in the Salem in the subsurface of

southern Illinois. Each cycle contains sediments deposited in

shallow subtidal shelf, oolite shoal, lagoon, and intertidal

environments. I have observed cycles similar to those

described by Cluff and Lineback at outcrops in Union

County, Illinois.

The St. Louis Limestone, overlying the Salem, consists

mainly of fine-grained cherty limestone and dolomite. The

most typical St. Louis lithology is bluish-gray “sublithographic” limestone that contains dark gray to black vitreous

chert nodules. Other rock types include fine-grained skeletal

wackestone and packstone, microsucrosic dolomite, and (in

subsurface) anhydrite (Cluff and Lineback, 1981). The St.

Louis contains more chert than adjacent units, and oolitic

limestone is uncommon. Both the upper and lower contacts

are gradational and intertonguing in most of the report area

and have been mapped at different positions by different

geologists.

The colonial corals Acrocyathus proliferus and A. floriformis are widespread and common in the St. Louis

(Grabowski, 1986). In southwestern Illinois the acme zone

of A. proliferus is at or close to the Salem–St. Louis contact,

whereas A. floriformis occurs in the upper part of the St.

Louis (Nelson, Devera, and Masters, 1995).

The St. Louis thickens from about 75 ft (23 m) in northern Perry and Ste. Genevieve Counties, Missouri, to as much

as 500 ft (150 m) in outcrops of southeastern Illinois and

western Kentucky. An isopach map by Willman and others

(1975, p. 141) shows more than 500 ft (150 m) of St. Louis

in the subsurface of Saline and Gallatin Counties, Illinois.

Intertonguing contacts and differing concepts of the formation prevent precise delineation of St. Louis thickness trends.

Cluff and Lineback (1981, p. 65) attributed fine-grained

carbonates of the St. Louis to shallow, subtidal, highly

restricted environments similar to modern Florida Bay.

Abundant subaerial exposure indicators and evaporites

around the margins of the Illinois Basin imply intertidal to

supratidal environments. Sable and Dever (1990) supported

those interpretations but suggested that upper part of the

Salem and the lower part of the St. Louis might have been

deposited in deep water below wave base.

The Ste. Genevieve Limestone is the youngest formation in the Mammoth Cave Group. White to light-gray, commonly cross-bedded, oolitic and skeletal grainstone is the

most typical lithology. Also present are packstones and

wackestones and intervals of dark, cherty lime mudstones

and dolomites similar to the St. Louis. The upper part of the

Ste. Genevieve is commonly sandy and contains lenses and

interbeds of sandstone and greenish-gray shale.

In most of the Paducah quadrangle, the lower contact of

the Ste. Genevieve is gradational and intertonguing; its

placement is somewhat arbitrary. However, this contact is an

angular unconformity in parts of Ste. Genevieve and Perry

Counties, Missouri, near the northwest corner of the quadrangle. Here, the bedding of the St. Louis is truncated, and

Ste. Genevieve sediments fill fissures at the top of the St.

Louis. Locally, the Ste. Genevieve has a basal conglomerate

of pebbles derived from the St. Louis along with clasts of

chert and limestone holding Middle Devonian corals and

brachiopods (Weller and St. Clair, 1928). These features

suggest tectonic activity along the Ste. Genevieve fault zone

prior to or during deposition of the Ste. Genevieve Limestone.

Thickness of the Ste. Genevieve varies from as little as

20 ft near Lithium, Missouri, where it is unconformable on

the St. Louis (Weller and St. Clair, 1928), to about 300 ft (90
B20 THE PADUCAH CUSMAP QUADRANGLE: RESOURCE AND TOPICAL INVESTIGATIONS

m) in the southeastern part of the study area. The Ste. Genevieve intertongues on a large scale with siliciclastic rocks of

the overlying Aux Vases Formation. Regionally, lower sandstone tongues of the Aux Vases pinch out toward the southeast, so that the top of the Ste. Genevieve rises southeastward

across time lines in a series of steps (Swann, 1963; Nelson

and Cole, 1992).

The Ste. Genevieve represents high-energy oolite

shoals surrounded by lower energy open-marine and

lagoonal areas where lime mud was deposited. Probably the

Ste. Genevieve was deposited in slightly deeper water than

the St. Louis (Cluff and Lineback, 1981).

POPE GROUP

The upper part of the Kaskaskia sequence is a succession of mixed carbonate and siliciclastic rocks assigned to the

Pope Group. Exposures of these strata along the Mississippi

River in southwestern Illinois and southeastern Missouri

constitute the type section of the Chesterian Provincial Series

(Upper Mississippian); however, placement of the lower

boundary of the series is still unresolved (Maples and

Waters, 1987). The contact between the Mammoth Cave and

Pope Groups is time transgressive and involves large-scale

intertonguing of carbonate and siliciclastic units (Swann and

Willman, 1961; Swann, 1963; Nelson and Cole, 1992).

On the geologic map (plate 1), the Pope Group is

divided into upper and lower units (map units Mpu and Mpl,

respectively) at the top of the Glen Dean Limestone, a

regionally continuous unit. The Pope outcrop belt extends

from the northwestern corner through the south-central part

of the quadrangle into the Rough Creek graben area, where it

is greatly dissected by faulting.

The Pope Group is divided into many formations, the

definitions of which commonly change at State boundaries.

Descriptions of individual formations are given in Nelson

(1995). A cross section (fig. 9) shows the relationships in the

lower part of the Pope Group in southern Illinois.

Thickness of the Pope Group ranges from about 500 ft

(150 m) near the northwest corner of the quadrangle to more

than 1,400 ft (430 m) in parts of southeastern Illinois and

western Kentucky. The thickness pattern reflects maximum

subsidence near the junction of the Reelfoot rift and Rough

Creek graben. Recent studies (Nelson, unpub. data) suggest

that faults in the Dixon Springs graben and Wabash Valley

area underwent small displacements during deposition of the

Pope Group. The Ozark dome was a positive area, as evidenced by thinning of units and changes from offshore to

shoal facies on its flanks.

The Pope Group contains roughly equal proportions of

limestone and siliciclastic rocks. Many limestones are

regionally extensive but intergrade laterally with siliciclastics (fig. 9). Limestones in the lower part of the Pope Group

(Glen Dean Limestone and older) lithologically resemble the

Ste. Genevieve Limestone. Light-colored crinoidal and

oolitic grainstones and packstones predominate; wackestones, lime mudstones, and micro-grained dolomites are

subordinate. Limestones in the upper part of the Pope Group

are generally darker, more argillaceous lime mudstones and

skeletal wackestones. Siliciclastic rocks include dark-gray,

olive-gray, and greenish-gray clay shales and silty shales;

burrowed and laminated siltstones; and light-gray, very fine

to fine-grained quartzarenitic sandstones. Variegated claystones, rooted intervals, and lenticular, shaly coals commonly occur in the upper part of siliciclastic intervals.

Limestones of the Pope Group contain abundant,

diverse, marine fossils and sedimentary features indicative of

shallow-marine deposition. They represent such environments as shallow subtidal shelf or ramp, ooid shoals, and

lagoons (Vincent, 1975; Treworgy, 1988). Most previous

geologists interpreted Pope siliciclastic rocks as largely fluvial and deltaic deposits laid down during regressive cycles

(Potter, 1962, 1963; Swann, 1963, 1964). Recent studies

(Cole, 1990; Nelson and Cole, 1992) indicate that siliciclastics, like carbonates, represent primarily shallow subtidal and

intertidal environments and that multiple provenance areas

were involved.

Following deposition of the Pope Group, the entire

region was subjected to erosion. A system of paleovalleys

was cut into Pope strata and filled with sediments of the

Absaroka sequence (Sevier, 1951; Bristol and Howard,

1971).

ABSAROKA SEQUENCE

The informally named Absaroka sequence of Sloss and

others (1949) and Sloss (1963) comprises rocks ranging from

Pennsylvanian through Early Jurassic age. In the Paducah

quadrangle, the sequence is represented by Morrowan (Early

Pennsylvanian) through Wolfcampian (Early Permian) rocks

(fig. 10). The great bulk of the sequence is Pennsylvanian;

Permian rocks are present only in small downfaulted slices in

Kentucky.

Classification of Pennsylvanian rocks has differed historically between Illinois, Indiana, and Kentucky. For this

project, I standardized formational nomenclature, following

recent interstate agreements of Jacobson and others (in

press). Thus, Absaroka sequence rocks in the Paducah quadrangle are divided into four map units: Caseyville Formation

(oldest), Tradewater Formation, Carbondale Formation, and

McLeansboro Group.

CASEYVILLE FORMATION

The Caseyville Formation (Morrowan age) occurs in

numerous grabens in the Illinois-Kentucky fluorspar district

and also around the rim of the Eagle Valley–Moorman




BEDROCK GEOLOGY OF THE PADUCAH 1°×2° CUSMAP QUADRANGLE B25

Scarcity of marine body fossils, common occurrence of

coal and plant fossils, and presence of cross-bedded

channel-form sandstones led previous geologists to conclude

that the Tradewater was deposited in largely nonmarine, fluvial, and deltaic environments (Potter, 1963; Ethridge and

others, 1973). Widespread marine indicators, including trace

fossils and tidally laminated sediments, have been described

in recent studies of the Tradewater (Devera, 1989; Devera

and others, 1992; Nelson and others, 1991; Kvale and

Archer, 1989). Probably the Tradewater, like the Caseyville,

represents alternating fluvial, deltaic, estuarine, and shallow

subtidal sedimentation controlled by eustasy, tectonic activity, and autocyclic processes. The change from quartz arenites of the Caseyville to lithic arenites of the Tradewater may

reflect “unroofing” of the crystalline basement in the eastern

source areas (Potter and Sevier, 1956; Nelson, 1989).

CARBONDALE FORMATION

The Carbondale Formation contains most of the minable coal deposits of the Illinois Basin. As mapped on plate

1, the Carbondale comprises strata from the base of the

Davis coal (east of long. 89° W.) or Colchester coal (west of

long. 89° W.) to the top of the Herrin coal (throughout the

quadrangle).

The Carbondale Formation is characterized by great lateral persistence of certain members—the coals, limestones,

and black fissile shales. The sandstones, siltstones, and gray

shales that volumetrically make up 90 to 95 percent of the

Carbondale are lithologically similar to those of the Tradewater. Carbondale strata exhibit pronounced cyclicity in vertical succession. The concept of the cyclothem originally

developed from studies of the Carbondale Formation (Langenheim and Nelson, 1992).

The Carbondale thickens eastward across the report

area, from about 175 ft (55 m) on the west to 400 ft (120 m)

on the east. Tectonic movements were less pronounced than

earlier in Pennsylvanian time. The Du Quoin monocline continued to rise (fig. 11), and small-scale movements along the

Rough Creek fault system may have triggered paleoslumping during Carbondale deposition (Nelson and Lumm, 1987;

Kolata and Nelson, 1991a).

In the typical Carbondale cyclothem, the coal (in situ

peat) is overlain by black fissile shale (highly restricted

marine, anoxic waters) and limestone with shelly fauna

(open-marine shelf). In some cases, a gray shale wedge

(estuarine, deltaic, or lacustrine) intervenes between coal

and black shale. The marine limestone is overlain by

upward-coarsening siliciclastics, locally incised by channel-filling sandstones and reflecting progradation of deltas

or shoreline. The cycle ends with rooted underclay, representing the paleosol on which the peat (coal) of the next

cycle accumulated.

Unquestionably, the Carbondale contains both marine

and terrestrial sediments. Because less siliciclastic sediment

was coming into the region, deposition of limestone was

more frequent. Greater tectonic stability is implied by the

great regional extent of many thin units. Arguments over the

factors that controlled cyclicity, including tectonic, eustatic,

autogenic, and others, are summarized in Langenheim and

Nelson (1992).

McLEANSBORO GROUP

Pennsylvanian strata overlying the Carbondale Formation in the report area are assigned to the McLeansboro

Group. The name McLeansboro replaces Sturgis Formation,

previously used for these rocks in western Kentucky,

because McLeansboro has priority (Nelson, 1995). The

McLeansboro underlies a broad area covering the north-central and northeastern parts of the Paducah quadrangle along

with the core of the Eagle Valley–Moorman syncline south

of the Rough Creek fault system. The McLeansboro outcrop

belt is mostly mantled by Quaternary deposits; the succession is based largely on borehole data.

The McLeansboro Group contains four formations:

Shelburn, Patoka, Bond, and Mattoon Formations (Jacobson

and others, in press). All are lithologically similar; boundaries are defined at the tops or bases of widespread limestone

members. No maps showing these limestones in the Paducah

quadrangle are available. Therefore, formations of the

McLeansboro Group are not differentiated on plate 1.

The McLeansboro Group lithologically resembles the

Carbondale Formation, containing numerous cyclic deposits

of sandstone, siltstone, shale, coal, and limestone. Coals of

the McLeansboro generally are thinner, and limestones of

the McLeansboro are thicker and more numerous than those

of the Carbondale. Coals, black fissile shales, and limestones

are widely traceable.

The top of the McLeansboro Group is an erosional surface overlain by Quaternary sediments throughout the Paducah quadrangle. The thickest preserved section is about

2,600 ft (790 m) thick, in a borehole just east of the Ohio

River in the Grove Center quadrangle, Union County, Kentucky (Palmer, 1976). The borehole lies in a deep northeast-trending graben on the south side of the Rough Creek

fault system. Wolfcampian (Early Permian) fusulinids were

described from a core about 2,150 ft (655 m) above the Herrin coal bed in another graben a few miles east of the Grove

Center quadrangle (Kehn and others, 1982). Therefore, Permian strata probably are present in the graben in the Grove

Center quadrangle also. These are the youngest known

Paleozoic rocks in the Illinois Basin.

Depositional and tectonic patterns established earlier in

Pennsylvanian time seem to have persisted into McLeansboro deposition. Thickness and facies patterns suggest, however, that the primary source of siliciclastic material shifted
B26 THE PADUCAH CUSMAP QUADRANGLE: RESOURCE AND TOPICAL INVESTIGATIONS

from the northeast to the south in late Missourian and Virgilian time (Nelson, Trask, and others, 1991; Weibel, 1992).

The shift in source area may reflect the uplift of mountains

south of the Illinois Basin as a consequence of the Ouachita

orogeny.

POST-PENNSYLVANIAN 

TECTONISM

Widespread faulting took place in the Paducah quadrangle after deposition of the Absaroka sequence and before

deposition of the Zuni sequence (Cretaceous). Two major

tectonic episodes have been inferred. The first involved

reverse and strike-slip faulting, folding, and igneous activity

consistent with compressional stress. This activity is

believed to be late Paleozoic (Late Pennsylvanian and Permian) and probably was associated with the compressional

Alleghany and Ouachita orogenies. The second episode

involved normal faulting indicative of extensional stress and

most likely was connected with widespread rifting during

Triassic and Jurassic time.

COMPRESSIONAL EVENTS

Compressional deformation took place in many parts of

the Paducah quadrangle. Deformation in the western part of

the quadrangle took place both during and after Pennsylvanian deposition, whereas that in the eastern part was largely,

if not entirely, post-Pennsylvanian.

In the western part of the report area, the Ste. Genevieve

fault zone underwent reverse displacement with attendant

monoclinal folding (fig. 6). Movement may have begun during late Chesterian time and definitely was under way in

Morrowan time while the Caseyville Formation was being

deposited (Poor, 1925; Desborough, 1961a, 1961b; Nelson

and Lumm, 1985). Displacement continued after Morrowan

sedimentation, producing as much as 4,000 ft (1,200 m) of

stratigraphic separation across the fault zone. The timing of

later movements cannot be deduced because post-Morrowan

strata have been eroded from the area.

The Du Quoin monocline, as previously mentioned,

rose intermittently during Pennsylvanian deposition, being

particularly active during Atokan and early Desmoinesian

time. The monocline underwent additional post-Pennsylvanian uplift, folding the youngest (Missourian) strata in the

area.

Numerous northwest-trending fault zones have been

mapped in Missouri southwest of the Ste. Genevieve fault

zone. These faults displace Devonian and older rocks and

appear to be offset by northeast-trending faults that also displace Cretaceous rocks. Little is known of the style of

deformation on northwest-striking faults in the Paducah

quadrangle. Using evidence from west of the Paducah

quadrangle, Clendenin and others (1989) inferred late Paleozoic(?) “upthrust” high-angle reverse and sinistral

strike-slip displacement along northwest-trending faults.

The events outlined above generally are consistent with

a stress field having maximum compression oriented

NE.-SW. to NNE.-SSW. Such a stress field is reasonably

associated with the late Paleozoic Ouachita orogeny, southwest of the area.

In the eastern half of the Paducah quadrangle,

high-angle dip-slip reverse displacements took place along

the Rough Creek–Shawneetown fault system and Lusk

Creek fault zone (fig. 12). The greatest vertical separation is

about 3,500 ft (1,070 m) along the east-trending portion of

the Rough Creek–Shawneetown just east of the big bend in

the fault system in southeastern Saline County, Illinois (Nelson and Lumm, 1987). The big bend represents juncture of

Reelfoot rift and Rough Creek graben boundary faults. West

of the big bend, the McCormick and New Burnside anticlines

are seismically shown to be thrust-folds detached within the

Paleozoic section (Nelson, 1987, and unpub. data). Farther

north, the Cottage Grove fault system is a right-lateral system

that exhibits less than a mile (1.6 km) of strike-slip and as

much as 200 ft (60 m) of dip-slip displacement. The Cottage

Grove displaces Missourian and older rocks, whereas peridotite dikes dated as Early Permian have intruded along some

of the faults (Nelson and Krausse, 1981; Nelson and Lumm,

1987). All deformation mentioned in this paragraph is consistent with NW.-SE. compressional stress applied in Late

Pennsylvanian and Permian time (Kolata and Nelson,

1991a).

The “crypto-explosive” structure Hicks dome, centered

in Hardin County, Illinois, was a center for igneous activity.

Ultramafic dikes radiate from the dome along a NNW.-trending axis, forming a bow-tie pattern (fig. 3). The dikes are

radiometrically dated as Early Permian (Zartman and others,

1967). Some of the dikes follow small strike-slip faults that

are offset by northeast-trending mineralized faults in the fluorspar district (Hook, 1974; Trace, 1974). On Hicks dome

itself are shatter breccias, vent breccias, and carbonatites,

along with unusual minerals (Bradbury and Baxter, 1992).

Explosive release of gases heated by or derived from alkalic

magma at depth is postulated (Bradbury and Baxter, 1992).

The orientation of dikes implies the principal compressive

stress axis was NNW.-ESE.

EXTENSIONAL EVENTS

Early Mesozoic(?) NW.-SE. extension of the eastern

part of the report area is implied by northeast-trending,

high-angle normal faults. The greatest concentration of such

faults is in the Fluorspar Area fault complex. These faults,

which are mineralized with fluorite and metallic sulfides,

parallel major Cambrian normal faults of the Reelfoot rift.

Some of them displace Early Permian ultramafic dikes. At
BEDROCK GEOLOGY OF THE PADUCAH 1°×2° CUSMAP QUADRANGLE B27

the edge of the Mississippi Embayment, the Fluorspar Area

faults displace Cretaceous strata, but vertical separations are

much greater on Paleozoic than Cretaceous rocks (Rhoades

and Mistler, 1941; Amos, 1967). Those observations indicate that most of the normal faulting was post-Permian,

pre-Cretaceous.

North of the Fluorspar Area fault complex, north- and

northeast-trending normal faults of the Wabash Valley fault

system displace Missourian (Upper Pennsylvanian) and

older rocks and apparently do not deform Quaternary sediments (Ault and others, 1980; Bristol and Treworgy, 1979).

Whether these faults exploited preexisting fractures is undetermined. A northeast extension of the Reelfoot rift into

southern Indiana was postulated (Braile and others, 1982;

Sexton and others, 1986), but published and proprietary seismic data fail to confirm existence of such a structure (Pratt

and others, 1989; Nelson, 1991).

Large-scale normal displacements took place along the

Lusk Creek fault zone and Rough Creek–Shawneetown fault

zone. The normal displacements post-dated late Paleozoic(?)

reverse displacements, returning the blocks south and southeast of the faults to, or below, the pre-Pennsylvanian position

(fig. 12). Slices of the hanging walls of the faults were

sheared off and left high within the fault zone. For example,

at Horseshoe, on the Gallatin-Saline County line along the

Shawneetown fault zone, a hanging-wall slice of New

Albany Shale (Upper Devonian) and Fort Payne Formation

(Mississippian) is juxtaposed with Pennsylvanian rocks on

both sides of the fault zone. As the hanging wall was lowered

during normal movements it was drag-folded, creating the

northern limb of the Eagle Valley–Moorman syncline

(Smith and Palmer, 1981; Nelson and Lumm, 1987; Nelson,

1991).

ZUNI SEQUENCE

The informally named Zuni sequence of Sloss and others (1949) and Sloss (1963) is represented in the Paducah

quadrangle by Upper Cretaceous and Paleocene strata in the

Mississippi Embayment (fig. 13). These weakly lithified

sediments crop out in an arcuate belt from southeastern Missouri across southernmost Illinois to western Kentucky, at

the northern edge of the embayment. Outliers occur farther

north on isolated hilltops and in grabens.

The oldest unit in the Zuni sequence is the Tuscaloosa

Formation (Upper Cretaceous), which is composed mainly

of chert gravel. The pebbles are mostly white to light gray,

stained yellow to brown, subrounded to subangular, and 1 to

3 inches (2.5 to 7.5 cm) in diameter. Occasional cobbles are

as large as 10 inches (25 cm). The gravel has a matrix of

light-gray clay, silt, and quartz sand and contains lenses of

the same materials. Cement is absent, except locally along

faults where ferruginous cements are present. Reddish-brown fine- to medium-grained sand and sandstone in

the Eddyville quadrangle, Kentucky, was mapped as Tuscaloosa (Rogers, 1963). The Tuscaloosa is lenticular, and

ranges from a few feet to 75 ft (23 m) thick in most of the

report area, reaching a maximum thickness of about 180 ft

(55 m) in the Calvert City quadrangle, Kentucky (Amos and

Finch, 1968).

The McNairy Formation (Upper Cretaceous) conformably overlies the Tuscaloosa or rests on Paleozoic bedrock

where the Tuscaloosa is absent. The McNairy consists of

sand and weakly indurated sandstone intercalated with lesser

amounts of clay, silt, gravel, and lignite. Sand is white to yellow, red, and brown, fine to medium grained, and is composed of quartz with conspicuous amounts of mica and some

glauconite. Scattered chert granules are present. A local

facies of the McNairy is white, well-sorted, cross-bedded

quartzarenite (informally known as Commerce quartzite),

found south and east of Cape Girardeau, Mo. (Johnson,

1985; Nelson and others, 1995). Clay and silt in the McNairy

are light to dark gray, micaceous and lignitic. Gravel is found

mostly near the base of the McNairy and can be difficult to

distinguish from Tuscaloosa gravel. Lignite beds are discontinuous and less than 1 ft (30 cm) thick. The McNairy attains

a maximum thickness of 450 ft (137 m) in southern Illinois.

The McNairy was interpreted as fluvial and deltaic sediments derived from metamorphic source terranes in the

Appalachians (Potter and Pryor, 1961). However, the Commerce quartzite (informal), a supermature quartzarenite that

contains bidirectional cross-bedding, probably is a nearshore

marine deposit.

The youngest Cretaceous unit in the report area is the

Owl Creek Formation, a discontinuous unit of micaceous,

glauconitic clay and silt. Sand occurs as scattered grains and

as laminae and lenses. Gastropods, pelecypods, cephalopods, and U-shaped burrows are common, indicating marine

sedimentation. The Owl Creek, identified at scattered localities in Illinois and Missouri, is less than 20 ft (6 m) thick.

Unconformably overlying Cretaceous strata is the Midway Group (Paleocene). Two formations are recognized: the

Clayton Formation and the Porters Creek Clay. The Clayton

Formation, which was not separated from the McNairy by

quadrangle mappers in Kentucky, is a thin but widespread

unit of green, greenish-brown, and orange-brown glauconitic clay. It is micaceous and contains lenses of sand, particularly near the base. The clay is commonly bioturbated, and

it contains bivalves, gastropods, and foraminifera. The Clayton is about 5 to 20 ft (1.5 to 6 m) thick in the report area. The

overlying Porters Creek Clay is largely massive and blocky

greenish-gray, olive-gray to black calcium montmorillonite

clay, mined for use as absorbants. Silt, sand, mica, glauconite, and lignite flakes are common near the base. Fossils

include gastropods, bivalves, radiolarians, palynymorphs,

and fish remains. The Porters Creek is 45 to 220 ft (14 to 67

m) thick, reaching its maximum in parts of Ballard and

McCracken Counties, Kentucky.

BEDROCK GEOLOGY OF THE PADUCAH 1°×2° CUSMAP QUADRANGLE B29

(1970) assigned a Pliocene to early Pleistocene age to the

Mounds based on regional relationships.

POST-CRETACEOUS TECTONISM

The Paducah quadrangle lies immediately north of the

most active earthquake region of the North American Midcontinent—the New Madrid seismic zone. The New

Madrid zone is an ancient zone of weakness, the Reelfoot

rift, that has been reactivated repeatedly since Cambrian

time (Braile and others, 1982; Kolata and Nelson, 1991).

Documenting post-Cretaceous tectonism is difficult

because Cretaceous and younger sediments are largely

unlithified and occur in areas of low relief. Recent mapping

provides convincing evidence of widespread tectonic faulting of Cretaceous and younger units in the southern part of

the Paducah quadrangle. The style and trend of these faults

are mostly consistent with the contemporary stress regime

and with the inferred style and trend of active faults in the

New Madrid area (fig. 14).

Northeast-trending faults of the Fluorspar Area fault

complex displace the Tuscaloosa and McNairy Formations

(Upper Cretaceous) at the edge of the Mississippi Embayment east of Paducah, Ky. (Rhoades and Mistler, 1941;

Amos, 1967, 1974; Amos and Finch, 1968; Amos and

Wolfe, 1966). Post-Cretaceous vertical separations are

small: 100 ft (30 m) or less, compared to separations as great

as 2,400 ft (730 m) on the same faults in Mississippian bedrock. The possibility of a strike-slip component to post-Cretaceous faulting has not been investigated.

Post-Cretaceous faulting is well known in the Thebes

Gap area, Missouri-Illinois (south of Cape Girardeau). Early

work in the area was summarized by McCracken (1971; p.

20, under heading “Commerce anticlinorium”), who concluded, “***deformation may still be in progress.” Johnson

(1985) mapped several northeast-trending faults displacing

the Wilcox Formation (Eocene) in the Missouri part of the

Thebes quadrangle. New mapping by Harrison and Schultz

(1992) at Thebes Gap shows a series of northeast-trending

fault zones that exhibit fracture patterns consistent with dextral strike-slip. Small pull-apart grabens (divergent wrenching) contain chaotically oriented blocks of Paleozoic,

Cretaceous, and early Tertiary formations. Units as young as

the Mounds Gravel (Miocene to early Pleistocene?) are

folded and offset by faults that bear horizontal striations.

Equivocal evidence further suggests that Pleistocene loess

may be faulted (Harrison and Schultz, 1992).

Thebes Gap is at the northeast end of the Benton Hills,

a range of hills known as Crowleys Ridge farther to the

southwest. Crowleys Ridge and the Benton Hills are composed of Cretaceous and Tertiary sedimentary formations

that rise above Holocene alluvium of the Mississippi flood

plain. Geophysical studies in northeast Arkansas indicate

that Crowleys Ridge is a tectonic uplift bounded by

northeast-trending, post-Eocene strike-slip faults (Van Arsdale and others, 1992).

On the eastern flank of the Ozark dome are small grabens that have anomalously large displacements. Examples

of such grabens are the Marble Hill, Scopus, Randol Creek,

and Radio Tower structures (McCracken, 1971) and other,

unnamed grabens mapped near the Jackson fault zone and

near the city of Cape Girardeau (Amos 1987a, 1987b; Satterfield, 1973). These structures are surrounded by Lower and

Middle Ordovician carbonate rocks (mostly dolomite) and

contain chaotic blocks of Ordovician, Silurian, and Devonian formations downdropped as much as 2,400 ft (730 m)

relative to the wallrocks. Such displacements contrast with

throws of less than 300 ft (90 m) on most other mapped faults

in the area. The McNairy Formation (Cretaceous) is downdropped in three of these structures, located in the Scopus

(Amos, 1987b), Marble Hill (Amos, 1987a), and Dongola

(Amos, 1981) quadrangles (fig. 14). A detailed map of the

Marble Hill structure is presented here (fig. 15). The structure occurs at the intersection of a lengthy fault zone that

strikes northwest and a shorter fault zone that strikes ENE.

The country rock is largely Ordovician Cotter Dolomite.

Blocks of various formations as young as the Silurian and

Devonian Bailey Limestone are in grabens along the northwest-trending fault zone. The narrower, ENE.-trending graben contains slices of Ordovician Powell and Smithville

Dolomites, displaced only a few hundred feet at most, along

with slices containing McNairy Formation. The picture

shown in figure 15 is incomplete because much of the structure (particularly west of the town of Marble Hill) is concealed by Quaternary alluvium.

McCracken (1971) suggested that features such as the

Marble Hill structure were produced by a combination of

tectonic activity and solution collapse. I contend that solution played, at most, a minor role in creation of these features. The Cotter Dolomite is less subject to karstification

than many other units in the study area, such as the Ordovician Kimmswick and Mississippian Salem and St. Louis

Limestones, wherein no such structures are found. These

grabens are closely similar to pull-apart structures created by

divergent wrench faulting in the Thebes Gap area (Harrison

and Schultz, 1992). Given a region broken by two or more

sets of intersecting fractures, any tangential stress would

produce extensional grabens along one or more sets of fractures.

Tectonic faults that displace Cretaceous and Eocene

sediments occur in Alexander and Union Counties, Illinois.

The longest of these faults trend mostly north-south; shorter

faults strike east-west and northeast-southwest. All faults dip

more or less vertically. Some display small “flower structures,” pull-apart grabens, and horizontal striations, which

imply an important element of strike-slip (Nelson and

Devera, 1994; Nelson, Devera, and Masters, 1995; Devera

and Nelson, 1995). The largest post-Cretaceous fault in the

area is labeled “Iron Mountain fault” in figure 14. The Iron


B32 THE PADUCAH CUSMAP QUADRANGLE: RESOURCE AND TOPICAL INVESTIGATIONS

———1981, Geologic map of the Dongola quadrangle, Missouri:

U.S. Geological Survey Miscellaneous Field Studies Map

MF–1363, scale 1:24,000.

———1985a, Geologic map of the Altenburg 71/2′ quadrangle, Perry County, Missouri: Missouri Geological Survey Open-File

Map OFM-85-221-GI, scale 1:24,000.

———1985b, Geologic map of the Crosstown 71/2′ quadrangle,

Perry County, Missouri: Missouri Geological Survey

Open-File Map OFM-85-222-GI, scale 1:24,000.

———1986a, Geologic map of the Belgique 71/2′ quadrangle, Perry County, Missouri: Missouri Geological Survey Open-File

Map OFM-86-234-GI, scale 1:24,000.

———1986b, Geologic map of the Kaskaskia 71/2′ quadrangle, Ste.

Genevieve County, Missouri: Missouri Geological Survey

Open-File Map OFM-86-232-GI, scale 1:24,000.

———1986c, Geologic map of the Lithium 71/2′ quadrangle, Perry

and Ste. Genevieve Counties, Missouri: Missouri Geological

Survey Open-File Map OFM-86-233-GI, scale 1:24,000.

———1987a, Geologic map of the Marble Hill quadrangle, Bollinger County, Missouri: U.S. Geological Survey Miscellaneous Field Studies Map MF–1900, scale 1:24,000.

———1987b, Geologic map of the Scopus quadrangle, Bollinger

County, Missouri: U.S. Geological Survey Miscellaneous Field

Studies Map MF–1910, scale 1:24,000.

Amos, D.H., and Finch, W.I., 1968, Geologic map of the Calvert

City quadrangle, Livingston and Marshall Counties, Kentucky:

U.S. Geological Survey Geologic Quadrangle Map GQ–731,

scale 1:24,000.

Amos, D.H., and Wolfe, E.W., 1966, Geologic map of the Little

Cypress quadrangle, Livingston, Marshall and McCracken

Counties, Kentucky: U.S. Geological Survey Geologic Quadrangle Map GQ–554, scale 1:24,000.

Ault, C.H., Sullivan, D.M., and Tanner, G.F., 1980, Faulting in

Posey and Gibson Counties, Indiana: Proceedings of the Indiana Academy of Science, v. 89, p. 275–289.

Baxter, J.W., and Desborough, G.A., 1965, Areal geology of the

Illinois fluorspar district, Part 2, Karbers Ridge and Rosiclare

quadrangles: Illinois State Geological Survey Circular 385, 40

p. and map, scale 1:24,000.

Baxter, J.W., Desborough, G.A., and Shaw, C.W., 1967, Areal

geology of the Illinois fluorspar district, Part 3, Herod and

Shetlerville quadrangles: Illinois State Geological Survey Circular 413, 41 p. and map, scale 1:24,000.

Baxter, J.W., Potter, P.E., and Doyle, F.L., 1963, Areal geology of

the Illinois fluorspar district, Part 1, Saline Mines, Cave in

Rock, Dekoven, and Repton quadrangles: Illinois State Geological Survey Circular 342, 44 p. and map, scale 1:24,000.

Becker, L.E., and Droste, J.B., 1978, Late Silurian and Early Devonian sedimentologic history of southwestern Indiana: Indiana

Geological Survey Occasional Paper 24, 14 p.

Bertagne, A.J., and Leising, T.C., 1991, Interpretation of seismic

data from the Rough Creek graben of western Kentucky and

southern Illinois, in Leighton, M.W., Kolata, D.R., Oltz, D.F.,

and Eidel, J.J., eds., Interior Cratonic Basins: American Association of Petroleum Geologists Memoir 51, p. 199–208.

Bickford, M.E., Van Schmus, W.R., and Zietz, I., 1986, Proterozoic

history of the midcontinent region of North America: Geology,

v. 14, p. 492–496.

Boucot, A.J., and Johnson, J.G., 1968, Brachiopods of the Bois

Blanc Formation in New York: U.S. Geological Survey Professional Paper 584–B, 27 p. and 8 plates.

Bradbury, J.C., and Baxter, J.W., 1992, Intrusive breccias at Hicks

dome, Hardin County, Illinois: Illinois State Geological Survey

Circular 550, 23 p.

Braile, L.W., Keller, G.R., Hinze, W.J., and Lidiak, E.G., 1982, An

ancient rift complex and its relation to contemporary seismicity

in the New Madrid seismic zone: Tectonics, v. 1, no. 2, p.

225–237.

Bristol, H.M., and Howard, R.H., 1971, Paleogeologic map of the

sub-Pennsylvanian (Upper Mississippian) surface in the Illinois Basin: Illinois State Geological Survey Circular 458, 16 p.

Bristol, H.M., and Treworgy, J.D., 1979, The Wabash Valley fault

system in southeastern Illinois: Illinois State Geological Survey

Circular 509, 19 p.

Buschbach, T.C., 1975, Cambrian System, in Willman, H.B., and

others, Handbook of Illinois Stratigraphy, Illinois State Geological Survey Bulletin 95, p. 34–46.

Clendenin, C.W., Niewendorp, C.A., and Lowell, G.R., 1989, Reinterpretation of faulting in southeast Missouri: Geology, v. 17,

no. 3, p. 217–220.

Cluff, R.M., and Lineback, J.A., 1981, Middle Mississippian carbonates of the Illinois Basin: Illinois Geological Society and

Illinois State Geological Survey, 88 p.

Cluff, R.M., Reinbold, M.L., and Lineback, J.A., 1981, The New

Albany Shale Group in Illinois: Illinois State Geological Survey Circular 518, 83 p.

Cole, R.D., 1990, The stratigraphy, petrology and depositional

environments of the Mississippian Aux Vases Formation

across the southern portion of the Illinois Basin: Carbondale,

Southern Illinois University, Ph.D. dissertation, 260 p.

Collinson, Charles, Becker, L.E., James, G.W., Koenis, J.W., and

Swann, D.H., 1967, Illinois Basin, in International Symposium

on the Devonian System: Alberta Society of Petroleum Geologists, v. 1, p. 993–971.

Collinson, Charles, Sargent, M.L., and Jennings, J.R., 1988, Illinois

Basin region, in Sloss, L.L., ed., Sedimentary Cover, North

American Craton, USA: Geological Society of America, The

Geology of North America, v. D-2, p. 383–426.

Collinson, Charles, and Scott, A.J., 1958, Age of the Springville

Shale (Mississippian) of southern Illinois: Illinois State Geological Survey Circular 254, 12 p.

Croneis, Carey, 1944, The Devonian of southeastern Missouri: Illinois State Geological Survey Bulletin 68, p. 103–131.

Desborough, G.A., 1961a, Sedimentational and structural dating of

Rattlesnake Ferry fault in southwestern Illinois: American

Association of Petroleum Geologists Bulletin, v. 45, no. 8, p.

1401–1411.

———1961b, Geology of the Pomona quadrangle, Illinois: Illinois

State Geological Survey Circular 320, 16 p. and map, scale

1:24,000.

Devera, J.A., 1986, Micropaleontology, carbonate petrography and

environment of deposition of the Grand Tower Limestone

(Middle Devonian) in southwestern Illinois and southeastern

Missouri: Carbondale, Southern Illinois University, M.S. thesis, 320 p.

———1989, Ichnofossil assemblages and associated lithofacies of

the Lower Pennsylvanian (Caseyville and Tradewater
BEDROCK GEOLOGY OF THE PADUCAH 1°×2° CUSMAP QUADRANGLE B33

Formations), southern Illinois, Illinois Basin Studies 1: Kentucky, Indiana, and Illinois Geological Surveys, p. 57–83.

Devera, J.A., and Fraunfelter, G.H., 1988, Middle Devonian paleogeography and tectonic relationships east of the Ozark dome,

southeastern Missouri, southwestern Illinois and parts of

southwestern Indiana and western Kentucky, in McMillan,

N.J., Embry, A.F., and Glass, D.J., eds., Devonian of the

World—Proceedings of the Second International Symposium

on the Devonian System: Canadian Society of Petroleum Geologists, v. 2, p. 179–196.

Devera, J.A., Mason, C.E., and Peppers, R.A., 1987, A marine

shale in the Caseyville Formation (Lower Pennsylvanian) in

southern Illinois [abs.]: Geological Society of America,

Abstracts with Programs, p. 220.

Devera, J.A., and Nelson, W.J., 1995, Geologic map of the Cobden

71/2-minute quadrangle, Jackson and Union Counties, Illinois:

Illinois State Geological Survey Map IGQ–16, scale 1:24,000.

Devera, J.A., Nelson, J, Kvale, E., Barnhill, M. Eble, C., Staub, J.

and DiMichele, W., 1992, Peat deposition on a tidally dominated coastline: Tradewater interval (Morrowan-Atokan, Pennsylvanian), Illinois Basin [abs.]: Geological Society of

America Abstracts with Programs, p. 202–203.

Drahovzal, J.A., Harris, D.C., Wickstrom, L.H., Walker, Dan,

Baranowski, M.T., Keith, Brian, and Furer, L.C., 1992, The

East Continent rift basin: A new discovery: Kentucky Geological Survey Special Publication 18, series XI, 25 p.

Droste, J.B., and Shaver, R.H., 1980, Recognition of buried Silurian reefs in southwestern Indiana—Application to the Terre

Haute Bank: Journal of Geology, v. 88, p. 567–587.

———1983, Atlas of early and middle Paleozoic paleogeography

of the southern Great Lakes area: Indiana Geological Survey

Special Report 32, 32 p.

———1987, Upper Silurian and Lower Devonian stratigraphy of

the central Illinois Basin: Indiana Geological Survey Special

Report 39, 29 p.

Ethridge, F.G., Fraunfelter, G. and Utgaard, J., eds., 1973, Depositional environments of selected Lower Pennsylvanian and

Upper Mississippian sequences of southern Illinois: Guidebook, 37th Tri-State Field Conference: Carbondale, Southern

Illinois University, 158 p.

Ervin, C.P., and McGinnis, L.D., 1975, Reelfoot rift: Reactivated

precursor to the Mississippi Embayment: Geological Society

of America Bulletin, v. 86, p. 1287–1295.

Freeman, L.B., 1951, Regional aspects of Silurian and Devonian

stratigraphy in Kentucky: Kentucky Geological Survey, series

IX, Bulletin 6, 565 p.

Grabowski, G.J., Jr., 1986, Mississippian System: in McDowell,

R.C., ed., The Geology of Kentucky, a Text to Accompany the

Geologic Map of Kentucky: U.S. Geological Survey Professional Paper 1151–H, p. 19–31.

Greb, S.F., 1989, Structural controls on the formation of the

sub-Absaroka unconformity in the U.S. Eastern Interior Basin:

Geology, v. 17, p. 889–892.

Greb, S.F., Williams, D.A., and Williamson, A.D., 1992, Geology

and stratigraphy of the western Kentucky coal field: Kentucky

Geological Survey, Bulletin 2, series XI, 77 p.

Harrison, Richard, and Schultz, Arthur, 1992, Faulting at Thebes

Gap, Mo.-Ill.: Implications for New Madrid tectonism [abs.]:

Geological Society of America, Abstracts with Programs, p.

190.

Heigold, P.C., 1991, Crustal character of the Illinois Basin, in

Leighton, M.W., Kolata, D.R., Oltz, D.F., and Eidel, J.J., eds.,

Interior Cratonic Basins: American Association of Petroleum

Geologists Memoir 51, p. 247–261.

Heigold, P.C., and Kolata, D.R. 1993, Proterozoic crustal boundary

in the southern part of the Illinois Basin: Tectonophysics, v.

217, p. 307–319.

Heigold, P.C., and Oltz, D.F., 1991, Seismic expression of the

stratigraphic succession, in Leighton, M.W., Kolata, D.R.,

Oltz, D.F., and Eidel, J.J., eds., Interior Cratonic Basins: American Association of Petroleum Geologists Memoir 51, p.

169–178.

Heyl, A.V., Jr., 1972, The 38th Parallel lineament and its relation to

ore deposits: Economic Geology, v. 67, p. 879–894.

Hildenbrand, T.G., 1985, Rift structure of the northern Mississippi

Embayment from the analysis of gravity and magnetic data:

Journal of Geophysical Research, v. 90, no. B14, p. 12,

607–612, 622.

Hildenbrand, T.G., Kane, M.F., and Hendricks, J.D., 1982, Magnetic basement in the upper Mississippi Embayment

region—A preliminary report, in McKeown, F.A. and Pakiser,

L.C., eds, Investigations of the New Madrid, Missouri, Earthquake Region: U.S. Geological Survey Professional Paper

1236–E, p. 175–184.

Hook, J.W., 1974, Structure of the fault systems in the Illinois-Kentucky fluorspar district, in Hutchison, D.W., ed., A Symposium

on the Geology of Fluorspar: Kentucky Geological Survey,

series X, Special Publication 22, p. 77–86.

Howe, J.R., and Thompson, T.L., 1984, Tectonics, sedimentation,

and hydrocarbon potential of the Reelfoot rift: Oil and Gas

Journal, November 12, 1984, p. 179–190.

Howe, W.B. (coordinator), and Koenig, J.W. (ed.), 1961, The

stratigraphic succession in Missouri: Division of Geological

Survey and Water Resources, v. XL, 2nd series, 185 p.

Jacobson, R.J., and others, in press, Towards a more uniform stratigraphic nomenclature for rock units (formations and groups)

for the Pennsylvanian System in the Illinois Basin: Illinois

Basin Studies 3, Indiana, Illinois, and Kentucky Geological

Surveys.

Johnson, W.D., Jr., 1985, Geologic map of the Scott City and part

of the Thebes quadrangle, Scott and Cape Girardeau Counties,

Missouri: U.S. Geological Survey Miscellaneous Field Studies

Map MF–1803, scale 1:24,000.

Kehn, T.M., Beard, J.G., and Williamson, A.D., 1982, Mauzy Formation, a new stratigraphic unit of Permian age in western

Kentucky: U.S. Geological Survey Bulletin 1529–H, p.

H73–H86.

Kisvarsanyi, E.B., 1981, Geology of the Precambrian St. Francois

terrane, southern Missouri: Missouri Division of Geology and

Land Survey, Report of Investigations 64, 58 p.

———1984, Precambrian tectonic framework of Missouri as interpreted from magnetic anomaly map: Missouri Division of

Geology and Land Survey, Contributions to Precambrian

Geology No. 14, part B, 19 p.

Klein, G. deV., and Hsui, A.T., 1987, Origin of cratonic basins:

Geology, v. 15, p. 1094–1098.

Koeninger, C.A., and Mansfield, C.F., 1979, Earliest Pennsylvanian depositional environments in central southern Illinois, in

Palmer, J.E., and Dutcher, R.R., eds., Depositional and Structural History of the Pennsylvanian System of the Illinois Basin,
B34 THE PADUCAH CUSMAP QUADRANGLE: RESOURCE AND TOPICAL INVESTIGATIONS

Part 2, Invited papers, [Field trip no. 9, Ninth International

Congress of Carboniferous Stratigraphy and Geology]: Illinois

State Geological Survey Guidebook 15a, p. 76–80.

Kolata, D.R., and Nelson, W.J., 1991a, Tectonic history of the Illinois Basin, in Leighton, M.W., Kolata, D.R., Oltz, D.F., and

Eidel, J.J., eds., Interior Cratonic Basins: American Association of Petroleum Geologists Memoir 51, p. 263–285.

———1991b, Basin-forming mechanisms of the Illinois Basin, in

Leighton, M.W., Kolata, D.R., Oltz, D.F., and Eidel, J.J., eds.,

Interior Cratonic Basins: American Association of Petroleum

Geologists Memoir 51, p. 287–292.

———1992, The New Madrid rift system—Its role in the evolution

of the Illinois Basin [abs.]: 10th International Basement Tectonics Conference, Program with Abstracts, p. 67.

Kolata, D.R., and Noger, M.C., 1991, Tippecanoe I subsequence,

Middle and Upper Ordovician Series, in Leighton, M.W., Kolata, D.R., Oltz, D.F., and Eidel, J.J., eds., Interior Cratonic

Basins: American Association of Petroleum Geologists Memoir 51, p. 89–99.

Kolata, D.R., Treworgy, J.D., and Masters, J.M., 1981, Structural

framework of the Mississippi Embayment of southern Illinois:

Illinois State Geological Survey Circular 516, 38 p.

Kvale, E.A., and Archer, A.W., 1989, Recognition of tidal processes in mudstone-dominated sediments, Lower Pennsylvanian,

Indiana, Illinois Basin Studies 1: Kentucky, Indiana, and Illinois Geological Surveys, p. 29–44.

Kvale, E.A., and Uhlir, D.M., 1988, Tidal influence in an upper

Caseyville (Lower Pennsylvanian) Gilbert-type deltaic

sequence, southern Illinois [abs.]: Geological Society of America, Abstracts with Programs, v. 20, no. 5, p. 353.

Langenheim, R.L., and Nelson, W.J., 1992, The cyclothemic concept in the Illinois Basin, in Dott, R.H., Jr., ed., Eustasy: The

Historical Ups and Downs of a Major Geological Concept:

Geological Society of America Memoir 180, p. 55–71.

Lasemi, Zakaria, Treworgy, J.D., Norby, R.D., Grube, J.P., and

Huff, B.G., 1994, Waulsortian mounds and reservoir potential

of the Ullin Limestone (“Warsaw”) in southern Illinois and

adjacent areas in Kentucky: Illinois State Geological Survey

Guidebook 25, 65 p.

Leighton, M.W., Kolata, D.R., Oltz, D.F., and Eidel, J.J. (eds.),

1991, Interior Cratonic Basins: American Association of Petroleum Geologists Memoir 51, 819 p.

Lineback, J.A., 1966, Deep-water sediments adjacent to the Borden

Siltstone (Mississippian) delta in southern Illinois: Illinois

State Geological Survey Circular 401, 48 p.

———1969, Illinois Basin—Sediment-starved during Mississippian: American Association of Petroleum Geologists Bulletin, v.

53, p. 112–126.

———1972, Lateral gradation of the Salem and St. Louis Limestones (Middle Mississippian) in Illinois: Illinois State Geological Survey Circular 474, 21 p.

———1981, The eastern margin of the Burlington-Keokuk (Valmeyeran) carbonate bank in Illinois: Illinois State Geological

Survey Circular 520, 24 p.

Lumm, D.K., Nelson, W.J., and Greb, S.F., 1991, Structure and

chronology of part of the Pennyrile fault system, western Kentucky: Southeastern Geology, v. 32, no. 1, p. 43–59.

Maples, C.G., and Waters, J.A., 1987, Redefinition of the Meramecian/Chesterian boundary (Mississippian): Geology, v. 15, no.

7, p. 647–651.

McCracken, M.H., 1971, Structural features of Missouri: Missouri

Geological Survey and Water Resources, Report of Investigations 49, 99 p.

Meents, W.F., and Swann, D.H., 1965, Grand Tower Limestone

(Devonian) of southern Illinois: Illinois State Geological Survey Circular 389, 34 p.

Middendorf, M.A., 1989, Preliminary geologic map of the Ware

quadrangle, Cape Girardeau County, Missouri: Missouri Geological Survey, scale 1:24,000.

Mikulic, D.G., 1991, Tippecanoe II subsequence, Silurian System

through Lower Devonian Series, in Leighton, M.W., Kolata,

D.R., Oltz, D.F., and Eidel, J.J., eds., Interior Cratonic Basins:

American Association of Petroleum Geologists Memoir 51, p.

101–107.

Nelson, W.J., 1987, Detached anticlines in the Illinois Basin [abs.]:

Geological Society of America, Abstracts with Programs, p.

236.

———1989, The Caseyville Formation (Morrowan) of the Illinois

Basin: Regional setting and local relationships, Illinois Basin

Studies 1: Kentucky, Indiana, and Illinois Geological Surveys,

p. 84–95.

———1991, Structural styles of the Illinois Basin, in Leighton,

M.W., Kolata, D.R., Oltz, D.F., and Eidel, J.J., eds., Interior

Cratonic Basins: American Association of Petroleum Geologists Memoir 51, p. 209–243.

———1995, Bedrock geology of the Paducah 1°×2° quadrangle,

Illinois, Kentucky, and Missouri: Illinois State Geological Survey Bulletin 102, 40 p. and 5 plates.

Nelson, W.J., and Bauer, R.A., 1987, Thrust faults in southern Illinois Basin—Result of contemporary stress? : Geological Society of America Bulletin, v. 98, p. 302–307.

Nelson, W.J., and Cole, R.D., 1992, Regional intertonguing of

lithologic intervals, Pope (Chester) Group, Illinois Basin [abs.]:

American Association of Petroleum Geologists Bulletin, v. 76,

no. 8, p. 1282.

Nelson, W.J., and Devera, J.A., 1994, Geologic map of the Jonesboro and Ware quadrangles, Union County, Illinois: Illinois

State Geological Survey Map IGQ–14, scale 1:24,000.

Nelson, W.J., Devera, J.A., and Masters, J.M., 1995, Geology of the

Jonesboro 15-minute quadrangle, southwestern Illinois: Illinois

State Geological Survey Bulletin 101, 57 p.

Nelson, W.J., and Harrison, R.W., 1993, Post-Cretaceous faulting at

head of Mississippi Embayment [abs.]: Geological Society of

America, Abstracts with Programs, North-Central Section

Meeting, Rolla, Mo., March 29–30, 1993, p. 69–70.

Nelson, W.J., and Krausse, H.-F., 1981, The Cottage Grove fault

system in southern Illinois: Illinois State Geological Survey

Circular 522, 65 p.

Nelson, W.J., and Lumm, D.K., 1985, Ste. Genevieve fault zone,

Missouri and Illinois: Illinois State Geological Survey, Contract/Grant Report 1985-3, 95 p.

———1987, Structural geology of southeastern Illinois and vicinity: Illinois State Geological Survey Circular 538, 70 p., 2

plates.

Nelson, W.J., Trask, C.B., Jacobson, R.J., Damberger, H.H., Williamson, A.D., and Williams, D.A., 1991, Absaroka

sequence—Pennsylvanian and Permian Systems, in Leighton,

M.W., Kolata, D.R., Oltz, D.F., and Eidel, J.J., eds., Interior

Cratonic Basins: American Association of Petroleum Geologists Memoir 51, p. 143–164.
BEDROCK GEOLOGY OF THE PADUCAH 1°×2° CUSMAP QUADRANGLE B35

Nelson, W.J., and others, 1991, Geology of the Eddyville, Stonefort, and Creal Springs quadrangles, southern Illinois: Illinois

State Geological Survey Bulletin 96, 85 p.

North, W.G., 1969, Middle Devonian strata of southern Illinois:

Illinois State Geological Survey Circular 441, 45 p.

Okhravi, R., and Carozzi, A.V., 1983, The Joachim Dolomite, a

Middle Ordovician sabkha of southeast Missouri and southern

Illinois, U.S.A.: Societe de Physique et d’Histoire Naturelle de

Geneve, v. 36, p. 373–424.

Olive, W.W., 1980, Geologic maps of the Jackson Purchase region,

Kentucky: U.S. Geological Survey Miscellaneous Investigations Series Map I–1217, scale 1:250,000, text 11 p.

Palmer, J.E., 1976, Geologic map of the Grove Center quadrangle,

Kentucky: U.S. Geological Survey Geologic Quadrangle Map

GQ–1314, scale 1:24,000.

Poor, R.S., 1925, The character and significance of the basal conglomerate of the Pennsylvanian System in southern Illinois:

Illinois State Academy of Sciences Transactions, v. 18, p.

369–375.

Potter, P.E., 1957, Breccia and small-scale Lower Pennsylvanian

overthrusting in southern Illinois: American Association of

Petroleum Geologists Bulletin, v. 41, no. 12, p. 2695–2709.

———1962, Late Mississippian sandstones in Illinois: Illinois

State Geological Survey, Circular 340, 36 p.

———1963, Late Paleozoic sandstones of the Illinois Basin:

Illinois State Geological Survey Report of Investigations 217,

92 p.

Potter, P.E., and Pryor, W.A., 1961, Dispersal centers of Paleozoic

and later clastics of the upper Mississippi Valley and adjacent

areas: Geological Society of America Bulletin, v. 72, p.

1195–1250.

Potter, P.E., and Siever, Raymond, 1956, Sources of basal Pennsylvanian sediment in the Eastern Interior Basin: [part 1] Journal

of Geology, Cross-bedding, v. 64, no. 3, p. 225–244; [part 2]

Sedimentary Petrology, v. 64, no. 4, p. 317–335.

Pratt, T., Culotta, R., Hauser, E., Nelson, D., Brown, L., Kaufman,

S., Oliver, J., and Hinze, W., 1989, Major Proterozoic basement features of the eastern Midcontinent of North America

revealed by recent COCORP profiling: Geology, v. 17, no. 6,

p. 505–509.

Pratt, T.L., Hauser E.C., and Nelson, K.D., 1992, Widespread buried Precambrian layered sequences in the United States Midcontinent: Evidence for large Proterozoic depositional basins:

American Association of Petroleum Geologists Bulletin, v. 76,

no. 9, p. 1384–1401.

Rhoades, R.F., and Mistler, A.J., 1941, Post-Appalachian faulting

in western Kentucky: American Association of Petroleum

Geologists Bulletin, v. 25, no. 11, p. 2046–2056.

Rogers, J.E., 1972, Silurian and Lower Devonian stratigraphy and

paleobasin development, Illinois Basin, Central U.S.: Urbana,

University of Illinois, Ph.D. thesis, 144 p.

Rogers, W.B., 1963, Geology of the Eddyville quadrangle, Lyon

and Caldwell Counties, Kentucky: U.S. Geological Survey

Geologic Quadrangle Map GQ–255, scale 1:24,000.

Ross, C.A., 1963, Structural framework of southernmost Illinois:

Illinois State Geological Survey Circular 351, 27 p.

———1964, Geology of the Paducah and Smithland quadrangles

in Illinois: Illinois State Geological Survey Circular 360, 32 p.

and map, scale 1:62,500.

Sable, E.G., and Dever, G.R., Jr., 1990, Mississippian rocks in Kentucky: U.S. Geological Survey Professional Paper 1503, 125 p.

Sargent, M.L., 1990a, Isopach map of the Everton Dolomite: Illinois State Geological Survey, unpub. map, scale 1:250,000.

———1990b, Isopach map of the St. Peter Sandstone: Illinois

State Geological Survey, unpub. map, scale 1:250,000.

———1990c, Isopach map of the Ottawa Supergroup: Illinois

State Geological Survey unpub. map, scale 1:250,000.

———1991a, Sauk sequence, Cambrian System through Lower

Ordovician Series, in Leighton, M.W., Kolata, D.R., Oltz,

D.F., and Eidel, J.J., eds., Interior Cratonic Basins: American

Association of Petroleum Geologists Memoir 51, p. 75–85.

———1991b, [Isopach map of] Mt. Simon and older sedimentary

rock: Illinois State Geological Survey, unpub. map, scale

1:250,000.

———1991c, Bonneterre/Eau Claire Formation—Limestone:dolomite in Illinois: Illinois State Geological Survey,

unpub. map, scale 1:250,000.

———1991d, [Isopach map of] Bonneterre/Eau Claire Formation:

Illinois State Geological Survey, unpub. map, scale 1:250,000.

———1991e, [Isopach map of] Knox Supergroup: Illinois State

Geological Survey, unpub. map, scale 1:250,000.

Sargent, M.L., and Roemelle, C., 1990, Isopach map of the

Maquoketa Group: Illinois State Geological Survey, unpub.

map, scale 1:250,000.

Sargent, M.L., Treworgy, J.D., and Whitaker, S.T., 1992, West-east

cross section in the Illinois Basin, Ozark dome, Missouri, to

Rough Creek graben, western Kentucky: Illinois State Geological Survey Open-File Series 1992-4.

Schwalb, H.R., 1982, Geologic-tectonic history of the area surrounding the northern end of the Mississippi Embayment: University of Missouri at Rolla Journal, no. 3, p. 31–42.

Schwalb, H.R., and Potter, P.E., 1978, Structure and isopach map

of the New Albany–Chattanooga–Ohio Shale (Devonian and

Mississippian) in Kentucky—Western sheet: Kentucky Geological Survey, series X, 1 sheet.

Sedimentation Seminar, 1978, Sedimentology of a paleovalley fill:

Kyrock Sandstone (Pennsylvanian) in Edmonson and Hart

Counties, Kentucky: Kentucky Geological Survey, series 10,

Report of Investigations 21, 24 p.

Sexton, J.L., Braile, L.W., Hinze, W.J., and Campbell, M.J., 1986,

Seismic reflection profiling studies of a buried Precambrian rift

beneath the Wabash Valley fault zone: Geophysics, v. 51, no.

3, p. 640–660.

Shaver, R.H. (coordinator), 1985, Midwestern basins and arches

region—Correlation of stratigraphic units of North America

(COSUNA) project: American Association of Petroleum Geologists, Chart MBA, 1 sheet.

Siever, Raymond, 1951, The Mississippian-Pennsylvanian unconformity in southern Illinois: American Association of Petroleum Geologists Bulletin, v. 35, no. 3, p. 542–581.

Sims, P.K., and Peterman, Z.E., 1986, Early Proterozoic Central

Plains orogen: A major buried structure in the north-central

United States: Geology, v. 14, p. 488–491.

Sloss, L.L., 1963, Sequences in the cratonic interior of North America: Geological Society of America Bulletin, v. 74, p. 93–114.

Sloss, L.L., Krumbein, W.C., and Dapples, E.C., 1949, Integrated

facies analysis, in Sedimentary Facies in Geologic History:

Geological Society of America Memoir 39, p. 91–123.
B36 THE PADUCAH CUSMAP QUADRANGLE: RESOURCE AND TOPICAL INVESTIGATIONS

Smith, A.E., and Palmer, J.E., 1981, Geology and petroleum occurrences in the Rough Creek fault zone: Some new ideas, in Luther, M.K., ed., Proceedings of the Technical Sessions: Kentucky

Oil and Gas Association, 38th Annual Meeting, June 6–7,

1974, [also Kentucky Geological Survey, series XI, Special

Publication 4, p. 45–59].

Soderberg, R.K., and Keller, G.R., 1981, Geophysical evidence for

deep basin in western Kentucky: American Association of

Petroleum Geologists Bulletin, v. 65, no. 2, p. 226–234.

St. Clair, Stuart, 1917, Clay deposits near Mountain Glen, Union

County, Illinois: Illinois State Geological Survey Bulletin 36,

p. 71–83.

Stark, J.T., 1992, In search of the East Continent rift complex: Evidence and conclusions [abs.]: 10th International Basement Tectonics Conference, Program with Abstracts, p. 141–142.

Swann, D.H., 1963, Classification of Genevievian and Chesterian

(Late Mississippian) rocks of Illinois: Illinois State Geological

Survey Report of Investigations 216, 91 p.

———1964, Late Mississippian rhythmic sediments of Mississippi

Valley: American Association of Petroleum Geologists Bulletin, v. 48, no. 5, p. 637–658.

Swann, D.H., Lineback, J.A., and Frund, E., 1965, The Borden Siltstone (Mississippian) delta in southwestern Illinois: Illinois

State Geological Survey Circular 386, 20 p.

Swann, D.H., and Willman, H.B., 1961, Megagroups in Illinois:

American Association of Petroleum Geologists Bulletin, v. 45,

no. 4, p. 471–483.

Tarr, W.A., and Keller, W.D., 1933, A post-Devonian igneous

intrusion in southeastern Missouri: Journal of Geology, v. 41,

p. 815–823.

Thompson, T.L., 1991, Paleozoic succession in Missouri—Ordovician System: Missouri Division of Geology and Land Survey

Report of Investigations 70, part 2, 282 p.

———1993, Paleozoic succession in Missouri—Silurian and

Devonian Systems: Missouri Division of Geology and Land

Survey Report of Investigations 70, part 3, 228 p.

Thompson, T.L., and Satterfield, I.R., 1975, Stratigraphy and conodont biostratigraphy of strata contiguous to the Ordovician-Silurian boundary in eastern Missouri: Missouri

Geological Survey Report of Investigations 57, pt. 2, p.

61–108.

Trace, R.D., 1974, Illinois-Kentucky fluorspar district, in Hutchison, D.W., ed., A Symposium on the Geology of Fluorspar:

Kentucky Geological Survey, series X, Special Publication 22,

p. 58–76.

Treworgy, J.D., 1988, The Illinois Basin—A tidally and tectonically influenced ramp during mid-Chesterian time: Illinois State

Geological Survey Circular 544, 20 p.

Treworgy, J.D., Whitaker, S.T., and Sargent, M.L., 1992, Southwest-northeast cross section in the Illinois Basin, southeastern

flank of Ozark dome, Missouri, to southern Illinois: Illinois

State Geological Survey Open-File Series 1992-2.

Van Arsdale, R.B., Williams, R.A., Schweig, E.S. III, Kanter, L.R.,

Shedlock, K.M., King, K.W., and Odum, J.K., 1992, Tectonic

origin of Crowleys Ridge, northeastern Arkansas [abs.]: Geological Society of America, Abstracts with Programs, p. 153.

Vincent, J.W., 1975, Lithofacies and biofacies of the Haney Limestone (Mississippian), Illinois, Indiana, and Kentucky: Kentucky Geological Survey, series X, Thesis Series 4, 64 p.

Weibel, C.P., 1992, Upper Pennsylvanian strata in the Illinois Basin

suggest compressional effect of Appalachian-Ouachita orogeny [abs]: Geological Society of America, Abstracts with Programs, p. 358.

Weibel, C.P., Nelson, W.J., Oliver, L.B., and Esling, S.P., 1993,

Geology of the Waltersburg quadrangle, Pope County, Illinois:

Illinois State Geological Survey Bulletin 98, 41 p.

Weller, Stuart, and St. Clair, Stuart, 1928, Geology of Ste. Genevieve County, Missouri: Missouri Bureau of Geology and

Mines, v. XXII, 2nd series, 352 p.

Whitaker, S.T., 1988, Silurian pinnacle reef distribution in Illinois:

Model for hydrocarbon exploration: Illinois State Geological

Survey, Illinois Petroleum 130, 32 p.

Whitaker, S.T., Treworgy, J.D., and Noger, M.C., 1992, 6 o’clock

cross section in the Illinois Basin, Wayne County, Illinois, to

Gibson County, Tennessee: Illinois State Geological Survey

Open-File Series 1992-10.

Whitaker, S.T., Treworgy, J.D., Sargent, M.L., and Noger, M.C.,

1992, Northwest-southeast cross section in the Illinois Basin,

Sparta Shelf, southern Illinois, to Rough Creek graben, western

Kentucky: Illinois State Geological Survey Open-File Series

1992-3.

Whitfield, J.W., and Middendorf, M.A., 1989, Geologic map of the

Neelys Landing 71/2′ quadrangle, Cape Girardeau County, Missouri: Missouri Geological Survey Open-File Map

OFM-89-254-GI, scale 1:24,000.

Willman, H.B., and Frye, J.C., 1970, Pleistocene stratigraphy of

Illinois: Illinois State Geological Survey Bulletin 94, 204 p.

Willman, H.B., and others, 1967, Geologic map of Illinois: Illinois

State Geological Survey, scale l:500,000.

Willman, H.B., and others, 1975, Handbook of Illinois stratigraphy:

Illinois State Geological Survey Bulletin 95, 261 p.

Zartman, R.E., Brock, M.R., Heyl, A.V., and Thomas, H.H., 1967,

K-Ar and Rb-Sr ages of some alkalic intrusive rocks from Central and Eastern United States: American Journal of Science, v.

265, no. 10, p. 848–870.

Zietz, Isidore, Bond, K.R., and Riggle, F.E., 1984, Magnetic anomaly map of Missouri: Missouri Department of Natural Resources, Contributions to Precambrian Geology, v. 14, part A, scale

1:100,000.

Published in the Central Region, Denver, Colorado

Manuscript approved for publication October 28, 1996

Edited by Richard W. Scott, Jr.

Page-size illustrations prepared by Jacquelyn Hannah,

Illinois State Geological Survey

Digital cartography on plate 1 by Barbara J. Stiff,

Illinois State Geological Survey

Conventional cartography and layout on plate 1 by

William E. Sowers

Photocomposition by Norma J. Maes