Shallow Deformation Along the Crittenden County

Fault Zone Near the Southeastern Margin of the

Reelfoot Rift, Northeastern Arkansas

U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1538-J

MISSOURI -"3K3fc-« — ;tfARKANSAS
Cover. Gray, shaded-relief map of magnetic anomaly data. Map area includes parts of 

Missouri, Illinois, Indiana, Kentucky, Tennessee, and Arkansas. Illumination is from the 

west. Figure is from Geophysical setting of the Reelfoot rift and relations between rift 

structures and the New Madrid seismic zone, by Thomas G. Hildenbrand and John D. 

Hendricks (chapter E in this series).
Shallow Deformation Along the Crittenden County 

Fault Zone Near the Southeastern Margin of the 

Reelfoot Rift, Northeastern Arkansas

By Eugene A. Luzietti, Lisa R. Kanter, Eugene S. Schweig III, 

Kaye M. Shedlock, and Roy B. VanArsdale

INVESTIGATIONS OF THE NEW MADRID SEISMIC ZONE 

Edited by Kaye M. Shedlock and Arch C. Johnston

U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1538-J

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1995
U.S. DEPARTMENT OF THE INTERIOR 

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY 

Gordon P. Eaton, Director

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

Luzietti, Eugene A.

Shallow Deformation Along the Crittenden County Fault Zone Near the Southeastern 

Margin of the Reelfoot Rift, Northeastern Arkansas / by Eugene A. Luzietti, Lisa R. Kanter, Eugene S. Schweig HI, Kaye M. Shedlock, and Roy B. VanArsdale

p. cm.—(Shallow Deformation Along Crittenden County Fault Zone, 

Arkansas ; J)

(U.S. Geological Survey professional paper ; 1538-J) 

Includes bibliographical references. 

Supt.ofDocs.no. ; I 19.16: 1538J

1. Earthquakes—Missouri—New Madrid Region. 2. Soil liquefaction— 

Missouri—New Madrid Region. I. Luzietti, Eugene A. n. Title. III. Series. 

IV. Series: U.S. Geological Survey professional paper ; 1538-J. 

QE535.2.U6159 1994vol. J 

551.2'2'09788985—dc20

[551.8'7'0976794] 93-37671

CIP
CONTENTS

Abstract................................................................................................................................. Jl

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

Geologic Setting................................................................................................................... 5

Data Acquisition and Processing.......................................................................................... 8

Interpretation......................................................................................................................... 9

BS-1 and BS-2.............................................................................................................. 9

GL-1, GL-2, and GL-3.................................................................................................. 12

GL-4.............................................................................................................................. 12

BS-3.............................................................................................................................. 19

BS-4.............................................................................................................................. 19

GL-5.............................................................................................................................. 20

Discussion and Conclusions................................................................................................. 20

Acknowledgments................................................................................................................ 22

References Cited................................................................................................................... 22

FIGURES

1. Relationship of earthquake epicenters, plutons, rift boundaries, and major geologic features in the New Madrid

	seismic zone to the study area.................................................................................................................................... J2

2. Illustration of style of faulting................................................................................................................................... 4

3. Location of the reflection profiles, wells, and cross section A-A'............................................................................ 5

4. Detail of cross section A-A'...................................................................................................................................... 6

5. Modified stratigraphic column of the Fort Pillow test well....................................................................................... 7

6. Profile BS-1..................................................................................................................................................^^ 10

7. Profile BS-2 ............................................................................................................................ 11

8. SP and resistivity log for the Wilson and Rankin No. 1 J.M. Leach well................................................................. 12

9. Profile GL-1...................................................................................................................................^ 13

10. Profile GL-3............................................................................................................................................................... 14

11. Profile GL-2............................................................................................................................................................... 15

12. Profile GL-4.....................................................................................................................................................^ 16

13. Profile BS-3 ............................................................................................................................................................... 17

14. Profile BS-4....................................................................................................................................................^ 18

15. Profile GL-5....................................................................................................................................................^ 19

16. Location of Crittenden County fault zone in relationship to Reelfoot rift boundary ................................................ 21

TABLES

1. Locations and names of selected drill-hole data........................................................................................................ J3

2. Data-acquisition parameters ...................................................................................................................................... 8

m

Shallow Deformation Along the Crittenden County

Fault Zone Near the Southeastern Margin of the

Reelfoot Rift, Northeastern Arkansas

By Eugene A. Luzietti, 1 Lisa R. Kanter,2 Eugene S. Schweig III,3 

Kaye M. Shedlock,4 and Roy B. VanArsdale5

ABSTRACT

The Crittenden County fault zone (CCFZ) is located 

near the southeastern boundary of the northeast-trending 

Reelfoot rift, which formed by Late Proterozoic and Cambrian extension. The southeastern boundary of the rift has 

been characterized as an 8-km-wide zone of 

down-to-the-northwest displacement. The CCFZ, however, 

shows significant down-to-the-southeast reverse faulting of 

Paleozoic and Cretaceous rocks and flexure and thinning 

within the Tertiary sedimentary section. This fault zone is 

located only 30 km from Memphis, Tenn., a metropolitan 

center of more than 800,000 people. To improve understanding of the location, attitude, and sense of displacement 

across the CCFZ, we have acquired 16.3 km of high-resolution shallow-reflection data in Crittenden County, Arkansas.

Nine Mini-Sosie (MS) profiles, varying in length from 

1 to 2 km, were collected across the projected surface locations of the CCFZ and the Reelfoot rift boundary. One second of two-way traveltime data was recorded, which 

corresponds to approximately 1.2 km of the crust. Sedimentary layers between 50 and 800 m deep are well imaged; 

deeper strata are evident but not well imaged.

Well data at one site on the CCFZ indicate approximately 63 and 82 m of vertical displacement of Cretaceous 

and Paleozoic rocks, respectively. Proprietary seismic 

reflection data show reverse displacement of these rock

Chevron USA Production Company, 935 Gravier St., New Orleans, 

LA 70112,

2Center for Earthquake Research and Information (CERI), Universty 

of Memphis, Memphis TN 38152.

U.S. Geological Survey, Center for Earthquake Research and Information (CERI), University of Memphis, Memphis TN 38152.

4U.S. Geological Survey, Mail Stop 966, P.O. Box 25046, Denver 

Federal Center, Denver, CO 80225.

5Department of Geology, University of Memphis, Memphis TN 

38152.

units, indicating compressional tectonics. From the 

Mini-Sosie profiles, we estimate structural relief across the 

CCFZ at the Fort Pillow Sand (Paleocene) level to range 

between 70 and 14 m. The overlying middle to late Eocene 

section shows a similar or slightly smaller amount of thinning, indicating that much of the movement on the CCFZ 

dates from this time. The amount of displacement, flexure, 

and thinning in the geologic section increases as the CCFZ 

converges with the Reelfoot rift boundary in the southwestern part of the area studied. Surface expression of the CCFZ 

has not been identified. The reflection from the Quaternary-Eocene unconformity, however, shows warping, dip, 

or interruptions in places over the CCFZ, suggesting that the 

CCFZ may have some very young movement as well.

INTRODUCTION

The New Madrid seismic zone (NMSZ), a branched 

concentration of earthquake epicenters in southeastern Missouri, northeastern Tennessee, and northeastern Arkansas, is 

the most seismically active area east of the Rocky Mountains; thus, the region around the NMSZ is the subject of 

ongoing research studies sponsored by the U.S. Geological 

Survey under the National Earthquake Hazards Reduction 

Program. Although a large percentage of the present-day 

NMSZ seismicity is microearthquake activity, possibly the 

largest known stable continental earthquakes in the world 

(Mw>8.0) occurred here during the winter of 1811-12 

(Johnston and Kanter, 1990). A recurrence of these earthquakes would likely result in loss of life and billions of dollars in structural damage to homes and buildings in the area.

Seismic reflection data have been important in improving our understanding of the subsurface geologic structures 

and their relationships to current seismic activity in this 

region. Vibroseis seismic reflection data have revealed a 

major zone of disturbed reflectors, the Blytheville arch, 

which correlates with the northeast trend of NMSZ

Jl
J2 INVESTIGATIONS OF THE NEW MADRID SEISMIC ZONE

—-—-—--—- MISSOURI ———,

+

ARKANSAS

f

35

25

I____L

50 KILOMETERS

Figure 1. Index map showing the location of the Crittenden County seismic reflection surveys (shaded box) in relation to 

the margins of the Reelfoot rift and plutons (Hildenbrand, 1985), the Blytheville arch (Hamilton and McKeown, 1988), the 

Pascola arch (Grohskopf, 1955), and epicenters of microearthquakes (crosses) (Taylor and others, 1991) in the upper Mississippi Embayment. Notice epicenters along the southeastern side of the rift boundary just north of the Covington pluton. The 

Fort Pillow test and No. 1 Houston Singer wells are also shown.
SHALLOW DEFORMATION ALONG CRITTENDEN COUNTY FAULT ZONE, NORTHEASTERN ARKANSAS D

Table 1. Location and names of selected drill-hole data identified in figure 3.

[Subsurface information from Dart (1990). Depth to top of Paleozoic in meters. Well ID is number keyed to locations shown on 

figure 3]

Well 

ID

AR18....

AR19....

AR20....

AR21....

AR22....

AR24....

AR57....

AR59....

Well 

name

....M.E. Davis

No. 1 DeMange 

...J.K. Dobbs

No. 1 Rowena D. Bond 

....H.L. Hawkins

R.G. OTSTeal 

...J.E. Stark, Jr.

R.G. OTSTealNo. 1-X 

....R.A. Johnson

No. 1 L. Alpe 

...J. Painter, Jr.

No. 1 P.M. Patterson 

....General Crude Oil

No. 1 L. Carruth Est. 

....Wilson and Rankin

No. 1 J.M. Leach

Well Depth to top 

location of Paleozoic

SWASWANEV* sec. 22, T. 8 N., R. 7 E. 902.21

NE%SE1/4SE1A sec. 22, T. 8 N., R. 8 E. 932.26

SW^SW^NE^ sec. 22, T. 8 N., R. 7 E. 897.94

SWASEV*NE1A sec. 22, T. 8 N., R. 7 E. 975.97

NWViNW^NW1^ sec. 23, T. 8 N., R. 7 E. 974.75

NW'/iNW'/iNWVi sec. 35, T. 9 N., R. 7 E. 929.95

N'/jNW1/^ sec. 5, T. 7 N., R. 8 E. 951.89

NEKSEKNEK, sec. 5, T. 7 N., R. 7 E. 984. 50

seismicity that extends from Marked Tree, Ark., to Caruthersville, Mo. (fig. 1) (Crone and others, 1985; Hamilton and 

McKeown, 1988; McKeown and others, 1990). Reflection 

data have also helped define subsurface structures (for 

example, the Cottonwood Grove fault) in the vicinity of the 

central NMSZ branch, which extends from Dyersburg, 

Tenn., to New Madrid, Mo. (Hamilton and Zoback, 1982; 

Crone and Brockman, 1982; Sexton and others, 1982). 

However, evidence of faulting is difficult to identify at the 

near-surface because of the intense geomorphic activity in 

the Mississippi River valley and the thick blanket of alluvium that covers this region.

During the past several years, seismic reflection profiles in this region have identified major faults that displace 

Paleozoic and Cretaceous rocks, but lack of resolution of 

Tertiary and younger strata has made it difficult to determine whether these faults continue into the Tertiary and 

Quaternary section. Several high-resolution shallow-reflection surveys undertaken in the NMSZ vicinity (Shedlock 

and Harding, 1982; Sexton and Jones, 1988; Luzietti and 

Harding, 1991) have been successful in identifying deformation and displacements in the Tertiary-age reflectors. 

However, little seismic reflection data is available that specifically targets the resolution or identification of near-surface faults that could generate destructive earthquakes or 

that identifies areas where trenching may yield recurrence 

rates of earthquakes.

The CCFZ lies off the NMSZ, close to the southeastern boundary of the Reelfoot rift. This boundary of the rift 

has been the locus of sparse seismicity (fig. 1) and is 

characterized by a zone about 8 km wide across which the 

cumulative vertical displacement is about 2 km at the level

of the Precambrian-Cambrian basal clastic sequence 

(McKeown and others, 1990). Hildenbrand and others 

(1982) deduce a similar value for magnetic basement displacement along this boundary. Even though very little 

seismicity has been recorded in this area, these vertical displacements indicate a potential for earthquakes along the 

southeastern margin of the rift if recurrent movement 

should occur along these basement-controlled fault zones.

A detailed interpretation of two proprietary reflection 

lines shows a reverse fault in profiles A and B (fig. 2)—these 

reflection lines are located about 5 and 2.5 km, respectively, 

northwest of the southeast edge of the rift boundary. This fault 

can be projected southwest to connect with a fault, first identified by Caplan (1954), in the Paleozoic section between 

wells AR18 and AR21 (table 1). The faulting is best demonstrated by a cross section between wells AR20 and AR21 

(table 1; figs. 3 and 4), which indicates that the Cretaceous 

and Tertiary sections are also involved in the deformation.

These observations indicate that there is a zone of 

deformation at least as young as Tertiary trending northeasterly near the rift boundary in Crittenden County, Arkansas. 

The fault interpreted on the cross section between wells 

AR20 and AR21, as well as the reverse faulting seen in the 

proprietary reflection data, will be referred to as the CCFZ.

In this paper, we use high-resolution shallow-reflection data to examine the extent, displacement, age, and 

deformation style of the CCFZ, particularly in the Cenozoic 

section. An understanding of the regional tectonic history 

and the identification of near-surface deformation is important in the determination of earthquake potential along the 

rift boundary, particularly in view of its close proximity to 

Memphis, Tenn.
J4 INVESTIGATIONS OF THE NEW MADRID SEISMIC ZONE

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SHALLOW DEFORMATION ALONG CRITTENDEN COUNTY FAULT ZONE, NORTHEASTERN ARKANSAS J5 

90°22'30" 17'30" 90°12'30"

17'30"-

35°15'

5 KILOMETERS

Figure 3. Index map showing locations of wells listed in table 1 and the nine seismic reflection lines (bold lines). Cross section 

A-A' is shown in figure 4. Locations of Mini-Sosie reflection lines (except GL-5) represent the surface approximation of the Crittenden County fault zone (CCFZ). Rift boundary (shaded) is interpreted from proprietary reflection data and coincides with the general location defined by aeromagnetic data.

GEOLOGIC SETTING

The NMSZ lies within the upper Mississippi Embayment, a broad south-southwest-plunging syncline that formed 

during the Cretaceous. The embayment overlies the Reelfoot 

rift, a southwest-trending graben about 65 km wide and 320 

km long (Hildenbrand, 1985). The Reelfoot rift formed in late 

Precambrian and Cambrian time and is filled with Precambrian and Cambrian elastics and Ordovician carbonates 

(Howe and Thompson, 1984). A major unconformity separates the Paleozoic rocks from the overlying Cretaceous and 

Tertiary sediments of the Mississippi Embayment. The Cretaceous and Tertiary strata are characterized by shallow-marine and fluvial, clastic sediments. The Fort Pillow test 

well (Moore and Brown, 1969), located 50 km northeast of 

our study area, penetrated the entire Mesozoic and Cenozoic

section. Figure 5 shows a generalized stratigraphic column 

from this well using the ages of Frederiksen and others (1982). 

In the Fort Pillow test well, the Cretaceous section consists of alternating sands and clays with minor silt. The sands 

range from consolidated and cemented to friable to loose. 

The overlying lower Paleocene section begins with a thick, 

homogeneous clay unit that includes the Clayton Formation 

and the Porters Creek Clay. Capping the lower Paleocene 

sediments is a sandy, micaceous silty clay known as the Old 

Breastworks Formation. The exact boundary between the 

lower Paleocene Old Breastworks Formation of the Midway 

Group and the upper Paleocene Fort Pillow Sand of the Wilcox Group is ambiguous (fig. 5). The Wilcox Group is subdivided into the Fort Pillow Sand and the Flour Island 

Formation, which consists of silt and clay with minor sand. 

The Paleocene-Eocene boundary is believed to fall within
J6 INVESTIGATIONS OF THE NEW MADRID SEISMIC ZONE

Wilcox Group

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contains thin silt and 

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UNCONFORMITY

Figure 5. A modified stratigraphic column taken from the Fort Pillow test well, Lauderdale County, 

Tennessee. Ages adjusted according to Frederiksen and others (1982). Upper boundary of the Clayton and 

lower boundary of Owl Creek are uncertain. The Cockfield is the upper formation of the Claiborne.
J8 INVESTIGATIONS OF THE NEW MADRID SEISMIC ZONE

the Flour Island Formation. The Claiborne Group, which 

overlies the Wilcox, is entirely of Eocene age and is represented by the thick Memphis Sand and silt and clay of the 

Cook Mountain Formation. The Cockfield Formation lies at 

the base of a series of interbedded sands and silts that are not 

subdivided in this well. The upper part of this series may 

belong to the Jackson Formation. The Tertiary sediments 

are much less consolidated than the Cretaceous section. An 

unconformity separates the Tertiary sediments from the 

Pliocene-Pleistocene terrace deposits, which is referred to 

here as the Quaternary section, and Pleistocene loess, which 

is not present in our study area. We used the spontaneous 

potential and resistivity logs from this well to identify the 

stratigraphy on additional logs obtained for our study area.

DATA ACQUISITION AND 

PROCESSING

Four east-west seismic reflection profiles and four 

north-south profiles were run across the surface projection 

of the CCFZ, and profile GL-5 was collected east of the 

CCFZ over the Reelfoot rift boundary defined by McKeown 

and others (1990) and Hildenbrand (1985) (this boundary 

does not coincide with the surface projection of the CCFZ; 

see fig. 3). These data were collected on paved and dirt 

roads—this provided compact soil conditions and ease of 

acquisition.

The Mini-Sosie acquisition method is a versatile, portable, high-resolution shallow-reflection technique that uses 

earth compactors as a source of random pulse energy. An 

earth compactor is a gasoline-driven machine operated by 

one person. At the foot of each compactor is a source sensor 

that identifies a time break for each impact and transmits it 

to the recording truck by radio where 1,000 samples of signal received by a geophone array are stored (time-record of 

the pulse onset). Time-records of seismic information overlap from all depths, but the final seismic record is produced 

in the field by a cross-correlation of previously stored 

time-records and succeeding incoming signals (Wiles, 

1979). The cross-correlation increases the signal-to-noise 

ratio of alike reflected energy and attenuates random noise. 

In this survey, three compactors advance parallel and (or) 

perpendicular to the profile line. A total of 2,000 random 

pulses from three simultaneously operating compactors is 

received and cross-correlated for each shotpoint. Table 2 

lists acquisition parameters in detail.

A great deal of testing and experimentation went into 

the reflection-survey-parameter design. The most critical 

aspect in acquiring good data was operating the compactors 

at a random and slow speed. When the operators exceed 24 

impulses per second, the recording system does not accept 

the radio-transmitted time breaks, and thus, the data cannot 

be cross-correlated with the incoming signal being measured by the geophones. Proper operation prevents the

Table 2. Data-acquisition parameters.

Parameter Description

Source type: 

Source array:

Source duration: 

Source point interval: 

Geophone array: 

Geophone spacing: 

Line array:

Field filters: 

Recording system: 

Sampling rate: 

Trace length:

Three earth compactors

5-m spacing, parallel/perpendicular

to profile line

2,000 impulses per shotpoint 

15.24m (50 ft) 

12 geophones in a cluster 

15.24m (50 ft) 

24 channels, on line,

0-30.48 m-381 m 

40-180Hz,24dB/octave 

I/O DHR 2400 

1 millisecond 

1 second

reflected signal from being contaminated by an oversaturated correlator in the recording truck.

The high water table and compact near-surface clays 

and sands provided ideal conditions for allowing energy to 

be transmitted into the ground without attenuating the relatively weak random signal. The subsurface geology is favorable, with a fairly uniform lateral velocity field and 

significant velocity and density contrasts at depth that reflect 

seismic energy back to the surface. The group interval and 

source to near-trace offset for these profiles were systematically designed to image reflectors between 50 and 800 m, 

targeting the Cretaceous unconformity as the deepest geologic objective. The top of the Paleozoic carbonate rocks, 

some 200-250 m below the top of the Cretaceous, was also 

imaged but was purposely truncated in the display because 

of migration end effects. The interval velocities in the upper 

1 km of the subsurface range between 1,100 and 2,800 m/s. 

In this data set, we were able to obtain a signal with a frequency range between 60 and 110 Hz. Using the "quarter 

wavelength rule" for vertical resolution (Yilmaz, 1987), features as thin as 5 m are resolvable.

The field data were processed with a standard sequence 

of processing steps at the U.S. Geological Survey facilities 

in Denver, Colo. Processing steps include: (1) tape reformat, 

(2) trace edit, (3) geometry definition, (4) 12-fold common 

midpoint (CMP) sort, (5) automatic gain control (AGC) with 

a 250-ms gate, (6) prestack spectral whitening, (7) two 

passes of normal moveout (NMO) velocity analyses every 

50 CMP, (8) residual surface-consistent statics, (9) mute and 

stack, (10) post-stack, second zero-crossing deconvolution, 

(11) post-stack finite-difference migration using 100 percent 

of the NMO velocities, and (12) bandpass filtering 

(25-35-140-160). The datum for these seismic profiles is 

67.0 m above sea level, which corresponds to the surface 

elevation in this area. The resulting record sections consist 

of 1-s two-way traveltime, corresponding to the upper 1.2 

km of the crust. All the profiles presented in this paper are 

migrated and are approximately 1:1 in scale.
SHALLOW DEFORMATION ALONG CRITTENDEN COUNTY FAULT ZONE, NORTHEASTERN ARKANSAS J9

INTERPRETATION

The nine reflection profiles show a great deal of lateral 

continuity and similarity in reflector character and structure. 

We were able to resolve coherent reflectors from about 

0.090 to 0.825 s (depths from about 50 to 800 m). Using the 

lithologic data and logs from the Fort Pillow test well as a 

guide, we obtained spontaneous potential (SP) and resistivity logs from wells in the area (table 1) and used them to 

identify geologic formations. None of these wells has a sonic 

log available to provide direct identification of the seismic 

reflectors and formations. The closest available sonic log, 

from the Houston Oil and Minerals No. 1 Singer well, 38 km 

west of our study area (fig. 1), showed excellent correlation 

between velocity contrasts and geologic formation breaks on 

the SP and resistivity logs in the study area. We thus identify 

the following reflectors on our profiles:

: Approximate location of the QuaternaryEocene unconformity. 

: Top of the Eocene and Paleocene Flour Island

Formation. Reflectors identified as Egf

represent the top of the Wilcox Group, which

corresponds to Eocene. 

PA£ Top of the Paleocene Fort Pillow Sand. 

PAP: Top of the Paleocene Porters Creek Clay. 

Kr: Top of undifferentiated Cretaceous rocks.

Proprietary reflection profiles with deeper resolution 

indicate the Crittenden County fault has reverse displacement 

in the Cretaceous and Paleozoic section (fig. 2). This information was helpful in providing the foundation of our interpretations of the Mini-Sosie data. Down-to-the-southeast 

displacement of the Cretaceous (Kr) reflector is interpreted 

as a zone of reverse faulting and is visible on all our profiles 

(figs. 6, 7, 9, 10, 11, 12, 13, and 14) except GL-5 (fig. 15). 

On GL-2, GL-3, and GL-4, the reverse faulting appears to 

involve the Porters Creek Clay (PAP)- Higher in the Tertiary 

section, in the Wilcox Group (Egf and P&f), this deformation 

is expressed primarily as a large down-to-the-southeast flexure accompanied by minor faulting. The strata involved 

appear to maintain fairly constant thicknesses. Although several of these minor faults directly overlie the reverse faults 

in the Cretaceous section, it is not clear that they are continuous or connected with the deeper reverse fault. In fact, some 

of the minor faults in the Wilcox Group have a sense of displacement opposite to that of the reverse faults in the Cretaceous reflectors, for example, GL-1 and GL-3.

The sedimentary section on the northwest side of the 

CCFZ is significantly thinner than that to the southeast of the 

CCFZ. The majority of this thinning occurs within the Claiborne Group (Memphis Sand and overlying units), indicating that relief existed on the CCFZ during this period of 

time. In contrast, no substantial thinning is seen between the

Cretaceous and the Porters Creek reflector or between the 

Porters Creek and the Flour Island reflectors.

Each seismic reflection profile is accompanied by a line 

drawing that delineates the prominent reflectors and marks 

the approximate location of geologic formations. At the 

right of each seismic profile, the depth is estimated every 0.1 

s. Depths across the time section may vary slightly. The 

accuracy of the depths below 0.7 s diminishes because the 

poor signal-to-noise ratio provides no accurate velocity control, although we still attempted to quantify the amount of 

displacement in the Cretaceous reflector if the record quality 

was adequate. Quantitative values for structural relief and 

thinning are based on interval velocities calculated between 

the Quaternary-Eocene reflector and the specific geologic 

interval being measured. The seismic reflection profiles all 

run south to north, or west to east, oblique to the CCFZ. 

Seismic reflection profile GL-5, located across the rift 

boundary, is described last.

BS-1 AND BS-2

Shotpoint 155 of BS-1 (figs. 3 and 6) ties with shotpoint 323 of BS-2 (figs. 3 and 7). The Wilson and Rankin 

No. 1 J.M. Leach well (AR59; fig. 8, table 1) can be projected 150 m along strike to the southern end of BS-2, allowing us to identify reflectors on these profiles with some 

confidence even though velocity or density information is 

not available. The top of the Cretaceous reflector is faintly 

imaged on both of these lines between 0.750 and 0.850 s. 

The poor velocity control below 0.7 s makes it difficult to 

quantify a displacement across the CCFZ.

BS-1 is of particular interest because it shows the maximum amount of structural relief seen in the study area, and 

this is accomplished without major faulting in the Tertiary 

section. The reflectors associated with the Wilcox Group 

show a monoclinal flexure, with the apex of curvature 

approximately located over the area we interpret as the location of the CCFZ. Within the Wilcox section, we calculate 

approximately 70 m of structural relief on the top of the 

reflector identified as the Fort Pillow Sand, assuming the 

interval velocity is about 2,000 m/s in both BS-1 and BS-2.

BS-1 clearly shows that most of the thinning in the geologic section occurs in the interval representing the Claiborne Group (between the reflectors labeled Egf and Q/EQ). 

This can be illustrated by the onlapping and truncation of 

high-amplitude reflectors between 0.10 and 0.225 s. The 

presence of onlapping reflectors suggests that the eastern 

side of BS-1 was subsiding relative to the western edge during Claiborne deposition, as opposed to having differential 

uplift and subsequent planar erosion after Claiborne deposition. We have calculated approximately 60-70 m of thinning 

between the top of the Flour Island and the Quaternary-Eocene unconformity boundary, assuming the interval 

velocity is approximately 1,960 m/s.
J10 INVESTIGATIONS OF THE NEW MADRID SEISMIC ZONE

WEST BS-1 ERST

SHOT 

POINT

0.0

Shot 155 of BS-1 ties 

with shot 323 of BS-2

CO

Q

o 

o

HI 

CO

HI

HI

I

1

0.9 -

- 860

- 979

CCFZ

Figure 6. Migrated seismic reflection profile BS-1 and line drawing. Q/EQ, Quaternary-Eocene unconformity boundary; Eof, Eocene 

Flour Island Formation; P^f, Paleocene Fort Pillow Sand; P^p, Paleocene Porters Creek Clay; Kr, Cretaceous rocks. The Crittenden County 

fault zone (CCFZ) is shown by a reverse fault below shotpoint 130. Notice the onlapping and high-amplitude reflectors between 0.100 and 

0.250 s, suggesting thinning of the geologic section occurred in the middle to late Eocene.
SHALLOW DEFORMATION ALONG CRITTENDEN COUNTY FAULT ZONE, NORTHEASTERN ARKANSAS Jl 1

SOUTH BS-2 NORTH

SHOT 

POINT

AR59

CO

o 

o

CO

z 

ul

UJ

i 

I

6

0.1 -

0.2 - 

0.3 - 

0.4 - 

0.5 - 

0.6 - 

0.7 - 

0.8 - 

0.9 -

Shot 323 of BS-2 ties 

with shot 155 of BS-1

— Q/EO

300 meters

730

860

1013

-60

-148

-250

-360

-474

-601

-730

-860

M013

CO

DC 

UJ

UJ

i

UJ 

Q 

UJ

X

g0_ 

0_

Figure 7. Migrated seismic reflection profile BS-2 and line drawing. Q/EQ, Quaternary-Eocene unconformity boundary; Eof, Eocene 

Flour Island Formation; PAf, Paleocene Fort Pillow Sand; PAP, Paleocene Porters Creek Clay; Kr, Cretaceous rocks. The Crittenden County 

fault zone is shown by a series of three reverse faults between shotpoints 350 and 375.
J12 INVESTIGATIONS OF THE NEW MADRID SEISMIC ZONE

SP

Wilson and Rankin 

No. 1 J.M. Leach

AR59 

KB=67.06

50

i

t

50

>

c.

S

c.

<"

>

^

<

^.

-^

^—

S

I

^-

_J

c^

\

^

J

f-

(m

ss"

f

)

^

(.

—

r

r^

y

-\

\

- — '

V

1

v-

;F

^

,/

'

V)

&~

;»»

-j

j

i

\

i~

'/

'

1

1

Depth 

(meters)

° 0 °

100

200

300

400

500

600

700

—— 800 ——

900

1000

0 C

i=

^S

ifJL,

^

s

f

>

>

f

i

t

f

X.

(

;

t

J

>

==

^t

^—

5».

K

D

«

-5

=Z

—

(0

~3

_/

t

J>

.a_

_s

==:

hrr

-

-?~

"2*

s)

x_•^

2C

2

0

(-39.62)

378.56

(-311.50)

443.18

(-376.12)

(-458.72)

- Cretaceous

791.56

f^ncn oo*J ooe o«a\

00

Figure 8. Spontaneous potential (SP) and resistivity logs of the 

Wilson and Rankin No. 1 J.M. Leach well (AR59) located in sec. 5, 

T. 7 N., R. 7 E. This well projects 150 m onto the southern end of 

seismic reflection profile BS-2.

GL-1, GL-2, AND GL-3

This is a series of three intersecting seismic lines, two 

running east-west (GL-1 and GL-3; figs. 3, 9, and 10) and 

one north-south (GL-2; figs. 3 and 11). Shotpoint 175 of 

GL-1 ties with shotpoint 331 of GL-2. Shotpoint 384 of 

GL-2 ties with shotpoint 419 of GL-3. Well AR21 was projected onto GL-2 and well AR 22 was projected onto GL-3 

to identify common reflectors associated with the same formation depths. These reflectors were then correlated with

reflectors on GL-1 at the appropriate tie point. Some discrepancies exist between formation depths and the reflectors 

identified from line to line. The discrepancies suggest that 

the interval velocities may not be accurate and reflect either 

poor estimations of the RMS velocities or wide variations in 

lithologic units across the fault zone.

Poor signal quality in the Cretaceous reflectors makes 

it difficult to calculate displacements in GL-1 and GL-3. 

However, using an interval velocity of about 2,800 m/s, the 

top of the Cretaceous reflector is displaced about 60 m in 

GL-2. This estimation of vertical displacement is consistent 

with the displacement in the Cretaceous shown in cross section A-A' (fig. 4). The reflector package corresponding to 

the Wilcox Group (Eof and P^f) indicates more brittle 

behavior than seen on BS-1 and BS-2. Each line has two 

broken regions, which we interpret as southeast-dipping 

reverse faults with an opposite sense of motion when compared with the deeper reverse fault in the Cretaceous. The 

fault geometry in the Wilcox Group makes it impossible to 

connect these faults to the deeper faults in the Cretaceous 

section.

We calculate 70,35, and 65 m of structural relief on the 

reflectors identified as the Fort Pillow Sand (PAf) in GL-1, 

GL-2, and GL-3, respectively. The geologic section representing the Claiborne Group thins over the Wilcox Group 

flexure. We calculate 60 m (GL-1), 35 m (GL-2), and 55 m 

(GL-3) of thinning in the Claiborne Group to the northwest. 

These discrepancies and inconsistent values of structural 

relief and thinning between these reflection profiles can be 

attributed to the poor velocity estimations. However, GL-2 

shows the best correlation between values calculated from 

the reflection profiles and cross section A-A'.

On GL-2, the time interval between 0.1 and 0.250 s 

shows the presence of high-amplitude and onlapping 

reflectors, indicating subsidence to the south during Claiborne time. In all of these lines, a reflector identified as the 

Quaternary-Eocene unconformity boundary (Q/Eo) shows 

warping and bulging directly over the main flexure in the Wilcox Group and the Cretaceous reverse fault (that is, GL-2, 

between shots 355 and 400). The Quaternary-Eocene reflector is at a depth equivalent to where this boundary has been 

mapped by Saucier (1964).

GL-4

GL-4 (figs. 3 and 12) is a north-south reflection profile 

that crosses the CCFZ between shots 715 and 760. The CCFZ 

is defined by a series of three reverse faults in the Cretaceous, 

with one possibly extending through the Porters Creek Clay. 

The reflectors within the Porters Creek Clay (PA?) and the 

Wilcox Group (P&f and Eof) show flexure to the south over 

the CCFZ. A minor fault is seen at shot 800 in this reflector 

package. Using an interval velocity of 1,900 m/s, we calculate
SHALLOW DEFORMATION ALONG CRITTENDEN COUNTY FAULT ZONE, NORTHEASTERN ARKANSAS

WEST GL-1 ERST

J13

SHOT S 

POINT <s

CO 

D

8

LU 

CO

LU

LU

6

0.1-

0.2-

0.3-

0.4

0.5-

0.6-

0.7-

0.8-

0.9-

AR20 AR21 Shot 175 of GL-1 ties 

with shot 331 of GL-2

142

239

357

490

623

co

755 CC 

LU

889

1025

- 60

LU

a

LU

X

o

142 £ 

Q_

— 239

- 357

- 490

- 623

- 755

- 889

- 1025

CCFZ

Figure 9. Migrated seismic reflection profile GL-1 and line drawing. Q/EQ, Quaternary-Eocene unconformity boundary; 

Eof, Eocene Flour Island Formation; PA^ Paleocene Fort Pillow Sand; PAP, Paleocene Porters Creek Clay; Kr, Cretaceous 

rocks. The Crittenden County fault zone (CCFZ) is shown by at least one reverse fault beneath shotpoint 120. Notice the minor 

normal and reverse displacements in the Wilcox reflectors and the substantial thinning of the time section above 0.3 seconds.
J14 INVESTIGATIONS OF THE NEW MADRID SEISMIC ZONE

WEST GL-3 ERST

SHOT 

POINT

CO 

Q

O 

O 

LU 

CO

LU

LU

1

I

6

0.1 -

0.2- 

0.3- 

0.4- 

0.5- 

0.6- 

0.7- 

0.8- 

0.9-

Shot 419 of GL-3 ties 

with shot 384 of GL-2

AR22

•Q/EO

781

925

CO 

DC 

LU

LU

1070

-73

-161

^260

-368

^486

-627

-781

-925

- 1070

O. 

LU 

Q 

LU

g

DC 

Q. 

Q.

Figure 10. Migrated seismic reflection profile GL-3 and line drawing. Q/EQ, Quaternary-Eocene unconformity boundary; Eof, Eocene 

Flour Island Formation; P^f, Paleocene Fort Pillow Sand; P^p, Paleocene Porters Creek Clay; Kr, Cretaceous rocks. The Crittenden County 

fault zone is shown by two reverse faults between shotpoints 420 and 445. Notice the high-amplitude seismic event at 0.2 s pinching out as 

the time section thins to the west. Structural warping and possible displacement is apparent in the Quaternary-Eocene reflector.
SHALLOW DEFORMATION ALONG CRITTENDEN COUNTY FAULT ZONE, NORTHEASTERN ARKANSAS J15

SOUTH GL-2 NORTH

SHOT 

POINT

CO

o

o 

o in

CO

III I

i

Shot 331 of GL-2 ties 

with shot 175 of GL-1 AR21

Shot 384 of GL-2 ties 

with shot 419 of GL-3

I I I I I I I

140

258

370

492

617

757

906

1058

CO

a: in

I

z

a. Ill 

o 

III

I I

a: 

a. 

a.

— 140

— 258

-370

— 492

^617

-757

-906

- 1058

CCFZ

Figure 11. Migrated seismic reflection profile GL-2 and line drawing. Q/EQ, Quaternary-Eocene unconformity boundary; Eof, Eocene 

Flour Island Formation; P^f, Paleocene Fort Pillow Sand; PAP> Paleocene Porters Creek Clay; Kr, Cretaceous rocks. The Crittenden 

County fault zone (CCFZ) is shown by two reverse faults between shotpoints 360 and 390. A noncoherent zone of energy is seen in the 

Wilcox reflectors between 0.350-0.450 s below shotpoint 380. This zone ties with the fault interpreted in GL-3. Notice the arching Quaternary-Eocene boundary over the zone of noncoherent energy and the CCFZ.
J16 INVESTIGATIONS OF THE NEW MADRID SEISMIC ZONE

SOUTH

SHOT 

POINT

GL-4 NORTH

CO 

Q

CO

LU 0.9

0.0

0.1-

0.2-

0.3-

0.4-

0.5-

0.6-

0.7-

0.8-

0.9-

•Q/EO583

708

829

CO 

CC 

LU

E0f

948 I

- 60

- 128

- 241

- 342

- 465

- 583

- 708

- 829

— 948

Figure 12. Migrated seismic reflection profile GL-4 and line drawing. Q/EQ, Quaternary-Eocene unconformity boundary; Eof, Eocene 

Hour Island Formation; P^f, Paleocene Fort Pillow Sand; P^p, Paleocene Porters Creek Clay; Kr, Cretaceous rocks. The Crittenden County 

fault zone is shown by three reverse faults between shotpoints 725 and 760.
SHALLOW DEFORMATION ALONG CRITTENDEN COUNTY FAULT ZONE, NORTHEASTERN ARKANSAS J17

SOUTH

SHOT <-n 

POINT i

BS-3 NORTH

CO 

Q

O 

O 

LU 

CO

LU

LJJ

?

DCII

6

-997

Figure 13. Migrated seismic reflection profile BS-3 and line drawing. Egf, Eocene Flour Island Formation; P^f, Paleocene Fort 

Pillow Sand; P^p, Paleocene Porters Creek Clay; Kr, Cretaceous rocks. The Crittenden County fault zone is a reverse fault below 

shotpoint 600.
J18 INVESTIGATIONS OF THE NEW MADRID SEISMIC ZONE

WEST

SHOT g 

POINT ea

BS-4 ERST

1057

CO 

CC111

111

i

in

Q

111

X

o

CC 

Q_ 

Q_

^495

— 623

^760

-898

-1057

CCFZ

Figure 14. Migrated seismic reflection profile BS-4 and line drawing. Egf, Eocene Flour 

Island Formation; P^f, Paleocene Fort Pillow Sand; P^p, Paleocene Porters Creek Clay; Kr, 

Cretaceous rocks. The Crittenden County fault zone (CCFZ) consists of two reverse faults 

between shotpoints 730 and 740.
SHALLOW DEFORMATION ALONG CRITTENDEN COUNTY FAULT ZONE, NORTHEASTERN ARKANSAS J19

SOUTH GL-5 NORTH

SHOT S 

POINT si

0.8

0.9

0.0

0.1-

0.2-

0.3-

0.4-

0.5-

0.6-

0.7-

0.8-

0.9-

— Q/EO -—

•Eof752

•PAf

•PA P

Kr

300 meters

Figure 15. Migrated seismic reflection profile GL-5 and line drawing. EQ{, Eocene Flour Island Formation; P^f, Paleocene Fort Pillow Sand; 

P^p, Paleocene Porters Creek Clay; Kr, Cretaceous rocks. GL-5 shows no displacement in the Cretaceous reflector. However, minor normal and 

reverse faulting and reflector warping are apparent in the Wilcox reflectors.

about 20 m of structural relief on the reflector interpreted as 

the Fort Pillow Sand. Over this flexure, we calculate about 

7 m of thinning to the south in the Claiborne Group.

BS-3

BS-3 (figs. 3 and 13) is a north-south reflection profile 

that crosses the CCFZ between shots 590 and 615. The 

Porters Creek Clay and Wilcox Group reflectors drape over 

the CCFZ to the south. Only minor faulting and reflector

warping is seen in the Wilcox Group. We cannot obtain an 

accurate estimate of the amount of structural relief and 

thinning over the CCFZ here because the end of the line was 

reached before the structure completely flattened.

BS-4

BS-4 (figs. 3 and 14) is an east-west line that crosses the 

CCFZ between shots 730 and 740, where two reverse faults 

are interpreted. Although the location of the Q/EQ reflector
J20 INVESTIGATIONS OF THE NEW MADRID SEISMIC ZONE

is somewhat ambiguous, we attempt to quantify structural 

flexure and thinning by approximating its location at 0.1 s. 

Using an interval velocity of approximately 1,900 m/s, we 

estimate about 15 m of structural relief on the Fort Pillow 

Sand and about 10 m of thinning in the Claiborne Group. 

The amount of relief on the flexure and thinning in the upper 

part of the Eocene section becomes significantly smaller 

than on profiles located farther to the southwest as the CCFZ 

converges on the rift boundary.

GL-5

GL-5 (figs. 3 and 15) is located approximately where 

McKeown and others (1990) identified the rift boundary as 

an 8-km-wide fault zone within Paleozoic-age rocks. The 

rationale for the placement of GL-5 was to try to understand 

how the northeast projection of the CCFZ and the margins 

of the Reelfoot rift boundaries are related. The profile shows 

clear, flat-lying, coherent reflectors that image the Cretaceous, Porters Creek Clay, and Wilcox Group. GL-5 apparently does not cross the CCFZ. Minor faulting and reflector 

warping that is interpreted in the Wilcox Group is not associated with deeper faulting and reflector flexure, as seen in 

the other profiles.

DISCUSSION AND CONCLUSIONS

Proprietary reflection data and well information at one 

location indicate that the CCFZ is a reverse fault that displaces Cretaceous and Paleozoic rocks as much as 60 and 83 

m, respectively. Faulting of this style is characteristic of 

compressional tectonics, as opposed to the extensional tectonics responsible for the formation of the Reelfoot rift during the Precambrian and Cambrian. The major flexure seen 

in the Tertiary section is consistent with compressional 

deformation.

The CCFZ intersects the rift boundary at its southern 

end and diverges from the rift boundary as it strikes northeast. Mini-Sosie reflection data indicate that time displacement of the Cretaceous reflector increases toward the 

southwest as the CCFZ converges with the rift boundary. 

However, poor velocity control below 0.7 s makes it difficult to quantify those displacements.

The interpretations of the Mini-Sosie reflection data 

and well-log information have allowed us to identify deformation associated with the CCFZ over a surface distance of 

16 km. Deformation of the Tertiary sediments appears as a 

monoclinal, southeast-dipping zone of flexure about 0.5 km 

wide—this is, thus, opposite in sense to the rift. Figure 16 

illustrates the location of the flexure zone. A maximum of 

70 m of structural relief on the Fort Pillow reflector (PAf on 

profile BS-1, fig. 16) is found at the southwestern edge of 

our study area.

The Quaternary and Tertiary section in the Mississippi 

Embayment consists of unlithified sediments rather than 

competent rock. We can thus expect ductile deformation in 

Tertiary rocks in response to recurrent movement along preexisting faults. The ductility of the Cenozoic sediments 

accounts for several features seen on the Mini-Sosie profiles: (1) the CCFZ reverse faults do not extend up into the 

Eocene section, although movement along the fault clearly 

occurred in the middle to late Eocene, (2) faulting interpreted in the Wilcox Group does not connect with that of the 

deeper reverse faults seen in the Cretaceous reflector, and 

(3) CCFZ movement is expressed as a large monoclinal flexure in the Tertiary section.

The lack of significant thinning between either the top 

of the Cretaceous section and the Porters Creek Clay (Paleocene), or the Porters Creek Clay and Flour Island Formation (Paleocene and lower Eocene), indicates that movement 

along the CCFZ was minimal during those geologic times. 

However, all the seismic reflection profiles (with the exception of GL-5) exhibit a substantial amount of thinning in the 

geologic section between the top of the Flour Island Formation and the Quaternary-Eocene unconformity. Coincident 

with the thinning is stratigraphic onlap within the Claiborne, 

indicating that most of the deformation probably occurred 

during Claiborne deposition.

The absolute age of the top of the Flour Island Formation is not well constrained, but falls somewhere in the early 

Eocene, perhaps around 52 Ma. The age of the base of the 

Quaternary is about 2 Ma, although the sediments we here 

call Quaternary may actually include some late Pliocene 

strata. We, therefore, can loosely bracket the majority of the 

deformation on the CCFZ to occur between 52 and 2 Ma. 

Using a maximum value of 70 m of thinning in the geologic 

section (BS-2), we calculate an approximate minimum vertical deformation rate of 1.4 m/m.y., which is a very slow 

rate.

The rock present between the top of the Flour Island 

Formation and the Quaternary-Eocene unconformity represents only about 18.5 m.y. and includes the Claibornian and 

Jacksonian Stages of the Eocene; the remainder of the Tertiary section is missing. If all of the deformation is 

pre-unconformity, we obtain an average vertical deformation rate of 3.8 m/m.y. for the CCFZ during the middle to 

late Eocene.

We have not identified any laterally continuous reflectors between the top of the Flour Island Formation and the 

Quaternary-Eocene unconformity. Examination of the 

reflector packages, however, indicates that nearly all of the 

thinning over the CCFZ occurs in the upper half of the Claiborne-Jackson section, which means that deformation rates 

were correspondingly higher. Within this upper half of the 

section, thinning appears to be distributed, perhaps with several pulses. On several of the profiles, at least some of the 

thinning occurs very near what we believe is the Quaternary-Eocene unconformity (for example, BS-1, shotpoint
SHALLOW DEFORMATION ALONG CRTTTENDEN COUNTY FAULT ZONE, NORTHEASTERN ARKANSAS J21 

90°22'30" 17'30" 90°12'30"

17'30"-

35°15'

5 KILOMETERS 

J

Figure 16. The location of the main zone of flexure in the Wilcox Group overlying the Crittenden County fault zone. The main 

zone of flexure dips to the southeast, indicating that the fault and flexure is opposite to the down-to-the-northwest normal 

displacement that marks the southeast boundary of the Reelfoot rift.

150, 0.1 s; BS-2, shotpoint 360, 0.1 s). It is possible that 

deformation continued during the time of the unconformity.

The evidence for compressional tectonics in the middle 

to late Eocene along the CCFZ is in accordance with the 

findings of Hamilton and Zoback (1982), who suggest that 

the reverse displacement along the Cottonwood Grove fault, 

in western Tennessee, occurred during middle to late Eocene 

time. We now have evidence of regional compressional 

forces that have affected an area of 85 km2 that spans from 

at least Cottonwood Grove, Tenn., to central Crittenden 

County, Arkansas.

The amount of Tertiary deformation and thinning 

decreases to the northeast as the CCFZ diverges away from 

the rift boundary. The proximity of the CCFZ to the rift 

boundary and its subparallel trend suggest that the CCFZ 

may be related to a zone of high-angle faults in basement

rocks that defines the rift boundary. The Reelfoot rift has a 

complex history of reactivation; recurrent movement of this 

zone of weakness along the rift boundary driven by regional 

stress may be responsible for the deformation we see in Tertiary sediments. Further evaluation of deeper reflection data 

is needed to resolve the structural relationship between the 

CCFZ and the southeast-bounding faults of the Reelfoot rift. 

A detailed examination of wells AR20 and AR21 (cross 

section A-A', fig. 4) indicates that the displacements from 

the Paleozoic up through the Flour Island Formation 

increase with depth and that the strata of the downthrown 

side are thicker than the correlative strata of the upthrown 

side. These differences may be due to differential compaction or original stratigraphic variations, but they likely indicate that the CCFZ itself has a history of reactivation. The 

different amount of vertical displacement at the top of the 

Paleozoic and Cretaceous gives direct evidence of this.
J22 INVESTIGATIONS OF THE NEW MADRID SEISMIC ZONE

Presently, the region is under east-northeast-directed 

compression (Zoback and Zoback, 1989; Dart and Swolfs, 

1991). Although microearthquake activity along the CCFZ 

is sparse (fig. 1), the presence of arching, disruption, and dip 

in the Quaternary-Eocene boundary (BS-2, BS-3, GL-1, 

GL-2, and GL-3) suggest that the CCFZ may have Quaternary activity. Focal-mechanism solutions for the arm of the 

NMSZ that trends from Marked Tree, Ark., to Caruthersville, 

Mo., indicate right-lateral strike-slip motion (Herrmann and 

Canas, 1978; Herrmann, 1979; Yang and others, 1991). It is 

reasonable to consider a right-lateral, strike-slip component 

along with reverse movement for the similarly oriented 

CCFZ. Pure strike-slip is very difficult to detect in seismic 

profiles. A combination of strike-slip and reverse displacement, however, might help to explain some of the minor 

faulting and arching seen on the profiles.

Reactivation of the CCFZ has resulted in reverse displacement of Paleozoic and Cretaceous rocks and flexure of 

overlying unconsolidated Tertiary sediments. The CCFZ 

may be currently undergoing strike-slip and (or) reverse 

compressional deformation in response to the present-day 

stress regime.

Additional work is needed to delineate the extent of the 

CCFZ to the northeast and southwest, to determine whether 

other, similar zones are present in the embayment, and to 

further examine the nature and amount of deformation in the 

Quaternary section.

ACKNOWLEDGMENTS

We would like to thank members of the U.S. Geological Survey's Mini-Sosie crew and the students from the University of Memphis for their participation in this field work, 

which contributed to the success of this project. We would 

also like to express our thanks to Warren Agena and John 

Miller of the USGS, who offered their expertise and advice 

in the processing of this data. We greatly benefited from discussions with Tony Crone, Joan Gomberg, and Hans 

Swolfs. Our special thanks go to Frank McKeown and Robert M. Hamilton, who suggested that this area be studied.

REFERENCES CITED

Caplan, W.M., 1954, Subsurface geology and related oil and gas 

possibilities of northern Arkansas: Arkansas Division of Geology Bulletin 20, p. 33.

Crone, A.J., and Brockman, S.R., 1982, Configuration and deformation of the Paleozoic bedrock surface in the New Madrid 

seismic zone, in McKeown, F.A., and Pakiser, L.C., eds., 

Investigation of the New Madrid Missouri Earthquake Region: 

U.S. Geological Survey Professional Paper 1236-1, p. 

115-135.

Crone, A.J., McKeown, F.A., Harding, S.T., Hamilton, R.M., Russ, 

D.P., and Zoback, M.D., 1985, Structure of the New Madrid 

seismic source zone in southeastern Missouri and northeastern 

Arkansas: Geology, v. 13, p. 547-550.

Dart, R.L., 1990, Catalog of drill-hole data from wells in the Paleozoic rocks on the upper Mississippi Embayment: U.S. Geological Survey Open-File Report 90-260, 136 p.

Dart, R.L., and Swolfs, H.S., 1991, Contemporary stress in northeastern Arkansas [abs.]: Eos, Transactions, American Geophysical Union, v. 72, no. 17, p. 264.

Frederiksen, N.O., Bybell, L.M., Christopher, R.A., Crone, A.J, 

Edwards, L.E., Gibson, T.G., Hazel, I.E., Repetski, I.E., Russ, 

D.P., Smith, C.C., and Ward, L.W., 1982, Biostratigraphy and 

paleoecology of lower Paleozoic, Upper Cretaceous, and lower Tertiary rocks in U.S. Geological Survey New Madrid test 

wells, southeastern Missouri, 1982: Tulane Studies in Geology 

and Paleontology, v. 17, no. 2, p. 23^5.

Grohskopf, J.G., 1955, Subsurface geology of the Mississippi 

Embayment of southeastern Missouri: Missouri Geological 

Survey and Water Resources Bulletin, v. 37, no. 5, p. 133.

Hamilton, R.M., and McKeown, F.A., 1988, Structure of the 

Blytheville arch in the New Madrid seismic zone: Seismological Research Letters, v. 59, no. 4, p. 117-121.

Hamilton, R.M., and Zoback, M.D., 1982, Tectonic features of the 

New Madrid seismic zone from seismic-reflection profiles, in 

McKeown, F.A., and Pakiser, L.C., eds., Investigations of the 

New Madrid Missouri Earthquake Region: U.S. Geological 

Survey Professional Paper 1236-F, p. 55-82.

Herrmann, R.B., 1979, Surface wave focal mechanisms for eastern 

North American earthquakes with tectonic implications: Journal of Geophysical Research , v. 84, p. 3543-3552.

Herrmann, R.B., and Canas, J., 1978, Focal mechanism studies in 

the New Madrid seismic zone: Bulletin of the Seismological 

Society of America, v. 68, p. 1085-1102.

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, p. 12607-12622.

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

39-53.

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

and hydrocarbon potential of the Reelfoot rift: Oil and Gas 

Journal, v. 82, p. 179-190.

Johnston, A.C., and Kanter, L.R., 1990, Earthquakes in stable continental crust: Scientific American, v. 262, no. 3, p. 68-75.

Luzietti, E.A., and Harding, ST., 1991, Reconnaissance seismic-reflection survey in the New Madrid seismic zone, northeast Arkansas and southeast Missouri: U.S. Geological Survey 

Miscellaneous Field Studies Map MF-2135.

McKeown, F.A., Hamilton, R.M., Diehl, S.F., and Glick, E.E., 

1990, Diapiric origin of the Blytheville and Pascola arches in 

the Reelfoot rift, east-central United States—Relation to New 

Madrid seismicity: Geology, v. 18, p. 1158-1162.

Moore, G.K., and Brown, D.L., 1969, Stratigraphy of the Fort Pillow test well, Lauderdale County, Tennessee: Tennessee Division of Geology Report of Investigations 26, 1 sheet and 

tables.
SHALLOW DEFORMATION ALONG CRITTENDEN COUNTY FAULT ZONE, NORTHEASTERN ARKANSAS J23

Saucier, R.T., 1964, Geological investigation of the St. Francis 

Basin: U.S. Army Corps of Engineers, Waterways Experiment 

Station Technical Report 3-659.

Sexton, J.L., Frey, E.P., and Malicki, D., 1982, High-resolution 

seismic-reflection surveying on Reelfoot scarp, northwestern 

Tennessee, in McKeown, F.A., and Pakiser, L.C., eds., Investigations of the New Madrid Missouri Earthquake Region: 

U.S. Geological Survey Professional Paper 1236-J, p. 

137-149.

Sexton, J.L., and Jones, P.B., 1988, Mini-Sosie high-resolution 

reflection survey of the Cottonwood Grove fault in northwestern Tennessee: Bulletin of the Seismological Society of America, v. 78, no. 2, p. 838-854.

Shedlock, K.M., and Harding, ST., 1982, Mississippi River seismic survey: Geophysical Research Letters, v. 9, p. 1275-1278.

Taylor, K., Stauder, W., and Herrmann, R., 1991, A comprehensive, unified data set for the New Madrid seismic array [abs.]: 

Seismological Research Letters, v. 62, p. 187.

Wiles, C.J., 1979, Mini-Sosie—New concept in high resolution 

seismic surveys: Oil and Gas Journal, v. 77, p. 94-97.

Yang, Y.T., Chiu, J.M., Liaw, Z.S., Chen, K.C., Chiu, S.C., 

Johnston, A.C., and Herrmann, R.B., 1991, Fault zone geometry and crustal velocity structures in the central New Madrid 

seismic zone using the PANDA data [abs.]: Eos, Transactions, 

American Geophysical Union, v. 72, no. 17, p. 264.

Yilmaz, O., 1987, Seismic Data Processing: Tulsa, Oklahoma, 

Society of Exploration Geophysicists, 57 p.

Zoback, M.L., and Zoback, M.D., 1989, Tectonic stress field of the 

continental United States: Geological Society of America, 

Memoir 172, p. 523-539.

Published in the Central Region, Denver, Colorado

Manuscript approved for publication September 7, 1994

Edited by Richard W. Scott, Jr.

Graphics prepared by Gayle Dumonceaux;

extensive use made of material supplied by John Michael, 

Branch of Earthquake and Landslide Hazards

Photocomposition by Mari L. Kauffmann

*U.S. GOVEKNMQH1 PRINTING OFFICE: 1995-673-046/86076