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1965 The Geologic Evolution of the Black Warrior Detrital Basin. Robert Ehrlich Louisiana State University and Agricultural & Mechanical College
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This Dissertation is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Historical Dissertations and Theses by an authorized administrator of LSU Digital Commons. For more information, please contact [email protected]. This dissertation has heen microfilmed exactly as received 66-726 EHRLICH, Robert, 1936— THE GEOLOGIC EVOLUTION OF THE BLACK WARRIOR DETRITAL BASIN. Louisiana State University, Ph.D., 1965 G eology
University Microfilms, Inc., Ann Arbor, Michigan THE GEOLOGIC EVOLUTION OF THE BLACK WARRIOR DETRITAL BASIN
A Dissertation
Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of Doctor of philosophy
in
The Department of Geology
by Robert Ehrlich B.A., University of Minnesota, 1958 M.S., Louisiana State University, 1961 August, 1965 ACKNOWLEDGMENTS
So many persons have given aid and encouragement during the progress of this problem that I approach these acknow ledgments with trepidations concerning possible omissions.
Conspicuous, however, is the importance of the teaching and advice of Dr. John C. Ferm who, besides being respon sible for that which is worthwhile in my training as a sedimentologist, has provided me with a model of high pro fessional integrity.
The Geological Survey and Oil and Gas Board of Alabama provided for field expenses and the cost of thin sections through its cooperative research program. However, the p "rsonal support and encouragement of individual members of that organization is appreciated as much or' more. Some of these Survey members include Philip E. LaMoreaux, State
Geologist, whose expressed confidence in the successful completion of this project sometimes exceeded my own; Charles
W. Copeland, Jr., Thomas J. Joiner, and Mrs. Jane W. Win- borne of the Stratigraphic Division; Thomas A. Simpson,
T. W. Daniel, Jr. and Otis M. Clark, Jr. of the Economic
ii Geology Division; and George Swindel, administrative geolo gist, who directed the admirable, logistical support.
Aid, advice and hospitality of Drs. Douglas E. Jones of the University of Alabama, John Carrington and William
Thomas of Birmingham Southern College are gratefully acknow ledged. Discussions with Dr. Reynold Q. Shotts, Professor, in the Alabama School of Mines, and with Donald Maples, graduate student at the University of Alabama, were of great value in understanding the petrology of the Basin.
The active cooperation of Donald Palmore, geologist with the Alabama Highway Department; the late R. S. Villad- sen, Walker County Engineer; Russel Boren, mining engineer; and officials of the Republic Steel Corporation is greatly appreciated. TABLE OF CONTENTS
Page
ACKNOWLEDGMENTS...... ; ...... ii
LIST OF FIGURES...... vi
ABSTRACT ...... vii
Chapter
I. INTRODUCTION...... 1
II. THE PETROGRAPHIC RECONNAISSANCE...... 4
III. THE GENERAL NATURE OF THE LOWERMOST SANDSTONE COMPLEX ...... 8
IV. REGIONAL VARIATIONS OF THE LOWERMOST SANDSTONE COMPLEX ...... 11
The northern orthoquartzite facies...... 11 The intermediate mixed facies ...... 11 The southern greywacke facies ...... 12 Summary of the observed facies pattern...... 12
V. MODELS OF COMPOSITIONAL VARIATION AND INFERENCES BASED ON T H E M ...... 16
The sedimentary-tectonic model...... 16 Preliminary interpretation of facies pattern. . 17 The model of total compositional variation. . . 18 Tectonic intensity factors...... 19 Methods for the removal of non-tectonic effects on mineral composition...... 19 Effects due to local current fluctuations . 19 Effects due to post-depositional mixing . . 20 Effects due to environmental differences and random variation...... 21
iv Page
. VI. THE SAMPLING P L A N ...... 23
Criteria for selection of sample localities . . 23 Intra-locality sampling plans ...... 25 Introduction. .25 Core sampling...... 25 Sampling at outcrop localities...... 27 Thin section technique...... 27
VII. OBSERVED MINERAL SPECIES...... 29
VIII. COMPOSITIONAL PATTERN OF THIN SECTION DATA. . . . 32
Areal compositional variation in the lowermost sandstone complex ...... 32 Removal of grain size effect on composition . 32 Regional pattern of compositional deviations. 33 The record of changes in tectonic intensity within the core ...... 37
IX. CORROBORATION OF OBSERVED LATERAL AND VERTICAL PATTERNS IN OTHER PARTS OF THE DETRITAL VOLUME...... 41
The basal limestone to shale facies change. . . 42 Facies change in the Jagger-Pratt interval. . . 42 Low quartzoseness of sandstone from the vicinity of Tuscaloosa...... 43 The southern conglomeratic facies ...... 43
X. SUMMARY AND CONCLUSIONS...... 45
SELECTED REFERENCES...... 49
APPENDIX ...... 53
VITA ...... 63
v LIST OF FIGURES
FIGURE Page
1. Regional Setting of the Black Warrior Basin. . . . 2
2. Total Thickness of Upper Carboniferous Detrital Sequence ...... 6
3. Geologic and Location Map of the Outcrop Area. . . 10
4. North-South Facies Relationship between Orthoquartzite and Greywacke F a c i e s ...... 14
5. Relationship between Quartzoseness and Grain Size of Core Samples ...... 34
6. Relationship between Quartzoseness and Grain Size of Samples from Localities within the Lowermost Sandstone Complex...... 3 5
7. Comparison of Quartz-Grain Size Relationships between Localities within the Lowermost Sandstone Complex...... 36
8. Deviations of Core Samples from Least Squares Line with Stratigraphic Position ...... 39
9. Total Quartz-Grain Size Relationship of Core Samples with Stratigraphic Position...... 40
10. North-to-South Generalized Cross-Section through the Detrital Volume...... In pocket
vi ABSTRACT
The Black Warrior Basin, located in northern Mississippi'
and Alabama, is bounded on the east and west respectively by
the northeast trending Appalachian and the northwest trend
ing Ouachita tectonic belts; and on the north by the broadly
arched Nashville-Ozark domal system. Excepting outcrops in
northern Alabama, the basinal character is obscured by the
post-Paleozoic sediments of the Gulf Coastal Plain and the
Mississippi Embayment. In the outcrop area, a mass of upper
Carboniferous (upper Chester and Pottsville) detritus caps
an otherwise predominantly carbonate early to middle Paleo
zoic succession. Detection and evaluation of patterns of
stratigraphic variation within the detritus exposed in the
Alabama outcrop area points to a greenschist-cored uplift
in southern Alabama as the source terrane of these sediments.
No such patterns were observed along east-west directions.
The main line of evidence was the documentation of a north-south compositional gradient (after the data was cleared
as much as possible of extraneous non-tectonic effects) in
the lowermost sandstone complex — with orthoquartzitic sands in the north intertonguing southward with sands containing
large amounts of greenschist detritus. The transition zone between these two facies lies between Gadsden and Birming ham. A similar, but vertical, pattern was observed in a continuous core from northern Tuscaloosa County wherein the
sediments contain a steadily increasing proportion of green
schist detritus upwards through the section.
These two lines of evidence, one concerning lateral trends and the other vertical, establish the main patterns of variation within the detrital volume. Other corrobora ting evidence taken from other parts of the basin include a north-to-south limestone to shale facies change in sediments below the lowermost sandstone complex; a southwards increase in sand content in the Jagger-Pratt interval above the com plex; the presence of a southern conglomeratic facies inter tonguing with a more northern sandy facies; and the very low quartzoseness of sandstones from the Tuscaloosa area — the southernmost sampled locality.
The patterns of grain size and compositional variation observed in the outcrop area of the Black Warrior Basin are the reflection of the influence of a source terrane, located in southern Alabama, being uplifted at an increasing rate
viii with eventual emergence of a greenschist core. This situ ation is interpreted to be a manifestation of a Ouachita uplift beginning in late Mississippian time. The inaugu ration of Appalachian uplift is considered to be distinctly later since its effects are not reflected in the sedimentary patterns, yet do structurally deform these sediments. Fur ther, the Ouachita structural trend must have extended much farther east than has now been determined in order to produce the observed patterns. Thus, the later Appalachian folding and uplift quite likely cross-cut this earlier tectonic trend. I
INTRODUCTION
The Black Warrior Basin presents a unique opportunity
to study the evolution of a detrital basin and to evaluate
the possible interactions between patterns of sedimentation
and the present tectonic boundary elements. The basin,
located in northern Alabama and Mississippi, is bounded on
the east and west respectively by the northeast trending
Appalachian and the northwest trending Ouachita tectonic belts,
and on the north by the Nashville-Ozark fonal system (see
fig. 1). Together with the Arkoma Basin, the Black Warrior
Basin may properly be considered as part of a larger detrital basin extending from Alabama to Texas.
Basinal character of Black Warrior Basin Sediments is
restricted to pre-Mesozoic rocks which, save for outcrops
in northwest Alabama, are now buried by the post-Paleozoic
deposits of the Gulf Coastal Plamnr-.and the Mississippi
Embayment. In the outcrop area, a mass of upper Car boniferous detritus (upper Chester and Pottsville in age)
several thousand feet thick caps an otherwise predominantly
1 Figure 1. Regional Setting of the Black Warrior Basin carbonate Paleozoic succession.
The delineation and character of the detrital source
terrane and relative dating of the uplift of the tectonic boundary welts was the purpose of a petrographic reconais-
sance of the outcrop area and is the subject of this report II
THE PETROGRAPHIC RECONNAISSANCE
The petrographic reconnaissance was designed to evalu ate the spectrum of megascopic variability with the late
Paleozoic detrital mass. This evaluation consisted of two phases: an early selection phase wherein, from the mul titude of available characteristics, a small number were selected for detailed observation; and a later synthetic phase wherein the patterns of variability and interrelation ships of these characteristics were determined.
The characteristics chosen were those whose scale of variation best suited the rather low level of stratigraphic control available in the outcrop area. The patterns of variation and covariation were originally field-determined, but were corroborated and amplified by thin section data.
Geographic location, total thickness, grain size, and mineral composition were easily observable characteristics and formed interrelated and meaningful patterns within the detrital volume. The thickness of the sequence at any location can, for instance, be predicted if the distance from
4 the northern margin of outcrop is known (figure 2). On the
other hand, little variation in thickness has been observed
along east-west directions. The values of the other
characteristics, grain size and mineral composition, can be
predicted with varying degrees of precision, if values of
thickness or location are known.
The interpretation of this pattern and those related
to it is ambiguous without some knowledge of the strati
graphic relationships within the detrital volume. The
ambiguity results from a wide latitude of choice of models
of stratigraphic variation; ranging from a model of wide
spread constancy of sequent unlike strata to a model of intra-
regional constancy of faciesr According to the first model,
the thickening and related lithic variation arises from
deposition and preservation of additional detritus upon
strata observed farther north. Acceptance of a model closer
to the second results in an interpretation involving pro
portional southward thickening of individual beds, as well
as intercalation of new units between them.
In order to resolve this ambiguity, special care was iaken to examine one unit, the lowermost sandstone complex,
that is conspicuously present over a wide area. The results 0 20 40 50 80 I II III I V MILES (South of N.Edge of Outcrop)
Figure 2 Total Thickness of Upper Carboniferous Detrital Sequence
6 of this examination not only fixed a model of stratigraphic variation relatively close to the model of regional con stancy of facies for north-south directions# but also shed enough light on the problems surrounding the provenance of the detritus to relegate other lines of evidence to a cor roboratory role. Ill
THE GENERAL NATURE OF THE LOWERMOST SANDSTONE COMPLEX
The stratigraphically lowest detritus wherever observ
ed, is a silty or clayey shale. This sequence, generally
finest near the underlying limestones, becomes coarser upwards by both increase in average particle size and by
increasing additions of thin beds of sandstone.
These shales are capped by a sandstone complex which is several hundred feet thick and composed of almost equal amounts of -massive sandstone and sandy siltstone. The sandstones, often cross-bedded, contain local concentra tions of quartz pebbles and woody debris. One or two coals are often observed within the included silty phases.
Major compositional changes in the sands are mani fested megascopically by color changes. The deepening of color from light grey or buff (value about 6.5) to dark greenish grey (about 5CT 6/1) signals a relative decrease in quartz content from near 100% ("orthoquartzitic" sand stones) to as low as 50% ("low rank greywacke" sandstones) and a concomittant increase in chloritic greenschist
8 detritus.
The complex, overlain by less resistant sediments, is a major ridge-former along the flanks of the Appalachian folds. Consequently, verification of lateral continuity of this unit for relatively great distances is not diffi cult.
Numerous road cuts afforded observations of the lower most sandstone complex from extreme northern Alabama to the
Birmingham area. These exposures, rimming the more western
Appalachian folds, provided a pool from which a more limited number were selected for more detailed examination and sampling (see fig. 3). Additional data was obtained from inspection and sampling a continuous core containing the entire detrital sequence in northern Tuscaloosa County. TEN N E E E
< a F ib iu i
Paleozoic ...» ... Pre-Detrital Sediments HUNTSVILLE a
Margin
GADSDEN
W arrior
Pinson
BIRMINGHAM
Metamorpnic TUSCALOOSA Igneous
Mmiicvallu
^ A L 10 T i- 50 J « . ______J "t mi le i p* > r* ,g ps * r 7 . < i >
Figure 3. Geologic and Location Map of the Outcrop Area
10 IV
REGIONAL VARIATIONS OF THE LOWERMOST SANDSTONE COMPLEX
The Northern Orthoquartzite Facies
Localities A, B, and C (figure 3), all located north of Birmingham, resemble one another both in grain size and mineral composition and accurately represent exposures of the complex located farther to the north, from Locality A to at least the Tennessee state line. All include ridge- forming sandstones as well as a basal sand unit resting on an underlying shale. Siltstone sequences iruterbedded with sandstones invariably contain coal but seldom, if ever, marine fossils. Shales underlying the complex contain scattered horizons containing marine fossils.
The great majority of the sands are orthoquartzitic, but minor amounts of darker colored greywacke occur near the tops of the exposures at localities B and C and also at
Boyles Gap (figure 3).
The Intermediate Mixed Facies
The situation at Locality D is complex. Here, about
11 12 half of the massive sandstones are dark-colored low rank greywackes and about half are orthoquartzites. The mixing of the two components occurs on many different scales— from -finely banded "gneissoid'1 sequences to juxtaposition of beds of greywacke and orthoquartzite ten or more feet thick. In addition, homogeneous beds of intermediate compo sition occur.
The Southern Greywacke Facies
At Locality E most sands are greywacke in composition with the possible exception of the capping sandstone bed.
In addition, greywacke sandstone is here observed inter bedded with the underlying marine shales— an occurrence not observed farther nprth.
Summary of the Observed Facies Pattern
The facies pattern observed within the lowermost sand stone complex can be described as a progressive southwards lateral replacement of orthoquartzitic sandstone by grey wacke sandstone plus invasion of the underlying marine shales with the dark-colored sandstone. This lateral replacement occurs only from Gadsden southwards; more northerly outcrops display little variation and seem to be 13 mainly orthoquartzitic. On the other hand, no such facies pattern has been observed anywhere along east-west lines
(i.e. through localities A, B, and C? or through E and the core location).
This pattern coupled with the presence of greywacke sandstones in sediments overlying the lowermost sandstone complex north of Birmingham (i.e. in the vicinity of Warrior) indicates that the facies change may be considered an inter- tongueing of a greywacke sandstone in the south with ortho quartzites in the north (figure 4). Thus the zone between s. Gadsden and Birmingham is transitional between the two facies.^
Besides yielding evidence on the mode of stratigraphic variation within the basin, further interpretation of this pattern — supplemented and refined with thin section data — yielded results bearing on the provenance of the detritus within the lowermost sandstone complex, and more generally,
•^Failure to recognize this pattern has resulted in the naming of the northern orthoquartzites "the Boyles sandstone member" of the Pennsylvanian Pottsville formation; the bulk of the southern greywackes the Mississipian "Parkwood" for mation; and the use of postulated unconformities to explain the distribution of each (see Butts, 1927; King, 1951; Kummel, 1961; etc.). I
Birmingham Lowermost Sand stone Complex
Figure 4. North-South Facies Relationship between Orthoquart- zite and Greywacke Facies on the provenance of the detritus within a major portion of the basin. These data, when interpreted in the light of a
sedimentary-tectonic model of compositional variation, con stitute the most important evidence in this study. V
MODELS OF COMPOSITIONAL VARIATION AND INFERENCES BASED ON THEM
The Sedimentary-Tectonic Model
The pattern of regional compositional variation of
sandstones can be interpreted in terms of provenance only
if a model or theory of compositional variation of sedi ments in response to tectonism is accepted; and if it can be shown that the observed mineralogical variation is not derived from factors independent of those enumerated in the model.
The model used here, derived from Krynine (1941-1942),
supposes that the composition of detritus deposited near a
source terrane more closely resembles the composition of that terrane than similarly generated detritus deposited
after longer transport. This change in bulk composition of detritus with increasing length of predepositional his tory is considered the result of the selective destruction of relatively unstable mineral species during the processes of erosion, transport and deposition. The regional pattern
16 17
at any one time is one of overlapping compositional gradi ents, one for each mineral species; with the decrease in relative abundance with distance from the source greatest for the most unstable species. Usually, this selective destruction results in quartz enrichment in the silt and sand size ranges because quartz is the most stable mineral commonly occurring in this range.
Preliminary Interpretation of Facies Pattern
In light of the model of tectonic-sedimentary compo sitional interaction, the megascopically observable pattern is interpreted as a reflection of the influence of a source terrane located in southern Alabama. This terrane included greenschist as a major lithologic component. Experience dictates that extensive exposures of greenschist are usually found in the core areas of uplifted sedimentary-metamorphic complexes and the southern source terrane is considered to be such a feature.
However, other factors may also affect the mineral composition of sediments. If a total model of compositional variation is accepted, samples may be collected according to a sampling plan to minimize these extraneous effects. Thin 18
section evaluation of these samples allows objective docu mentation of the necessarily subjective field impressions by more clearly isolating the tectonic component of compo
sitional variation from those arising in response to other
factors.
The Model of Total Compositional Variation
The total amount of compositional variation between
samples from a single sedimentary basin represents, according to this larger model, the response at a particular location to one or a combination of the following six factors:
(1) geographical movement of the source terrane
relative to the sample location?
(2) variations in the rate of uplift or erosive
denudation of the source terrane;
(3) local fluctuations of current velocity reflected
as grain size differences;
(4) post-depositional "mixing";
(5) changes in depositional environment not related to
local fluctuations in current velocity and loosely
coupled, if at all, with conditions of the source;
and 19
(6) random fluctuations inherent in any process
of an essentially steady-state nature.
Tectonic Intensity Factors
The first two factors enumerated above are of greatest interest here. However, the effect of (say) an increase in rate of localized uplift (factor 1) cannot here be distin guished from that due to an approaching "ripple" of tectonic activity of fairly constant amplitude ( factor 2). Thus, an increase in relative abundance of tectonicaly related mineral components (such as schistose detritus) vertically through a sequence at a single location can only be inter preted (all other factors eliminated) as a manifestation of either of these factors.
Methods for Removal of Non-tectonic Effects on Mineral Composition
Effects due to Local Current Fluctuations
Variation of mineral composition with changes in grain size is- displayed, for example, in a fluvial system, by dif ferences observed between a relatively quartzose sandy point bar and an adjacent clayey fine grained backswamp deposit.
The wide oscillations in composition produced by local vagaries of current and geography can be reduced or removed 20 if/the mineral composition of the deposited sediment is evaluated in relation to its grain size. This technique
(developed qualitatively by Ferm (1957)), described more fully in a later section, is based on measuring compositional deviations of samples from a calculated least-square line of best fit.
Effects due to Post-depositional Mixing
If water laid sediments, composed of layers of differing grain size and composition, are subsequently subjected to disruption and concomittant mixing, the resulting sedimen tary characteristics are influenced by the amount of varia tion originally present between the layers, the relative abundance of each type of layer, and the efficiency of the mixing process. Since none of these factors (confounded as they are) are of much interest here, "mixed" rocks were excluded from the ensuing analyses. These include "mud flows" characterized by extremely contorted bedding and sediments disrupted and redistributed by burrowing organisms. 21
Effects due to Environmental Differences and Random Variation
Some differences between environments are tectonically controlled (i.e., compare alluvial fan material at the base of a block faulted mountain with beach sediment accumulated on the edge of a static continent); differences due to these, when present, are pertinent. The environmental differences that interfere with the objectives of an investigation such as this are those that produce inter-locality variation in excess of the true gross difference between localities
(e.g., comparing a beach sand from one locality to a river sand from another — when both localities contain the same relative proportions of beach and river sand).
Random variation is ascribed to differences between samples that cannot be distinguished from random fluctu ations associated with a steady state process. Again, as above, this form becomes onerous only when it is impossible to decide whether or not random fluctuations account for most of the inter-locality variation.
These two sources of variation affecting mineral com position of sediments can neither be eliminated by exclusion from sampling nor analytical manipulation of the data. Instead, the effects of both can be minimized by taking more
than one sample at each locality. Good multiple sampling plans reduce the chance that an atypical minor constituent will represent a locality and also allows definition of a
"central value" estimate (i.e. mean, mode, etc.) that
reacts more sluggishly to random variation than do the
constituent data values. Thus if the number of intra
locality samples is high enough, both of these factors can be minimized. VI
THE SAMPLING PLAN
Samples to be thin sectioned were collected from a carefully selected array of localities. The criteria for sample selection, both regarding choice of sampled locality and choice of samples from a locality, are critically important; for they .define and limit the range of inferences that can be drawn from the data.
Criteria for Selection of Sample Localities
The sampled localities, except for a core located in northern Tuscaloosa County, are outcrops located along the strike of the Appalachian folds. The outcrop localities were chosen from those available on the basis of relative location, relative exposed thickness, and freshness of exposure.
Geographically, the sample locations constituted a sufficiently widespread yet dense enough array to detect and evaluate the potential directions of facies change.
The complete array of sample localities (figure 3) is
23 24 peculiarly sensitive to effects (as gradients of variation) emanating from either of the tectonic boundary welts ■— av Appalachian or Ouachita. If only one of these potential sources of detritus were active during deposition of these sediments, a gradient should exist at a high angle to that trend (e.g. relatively unstable detrital particles should accumulate near the source and decrease in relative abun dance away from it).
At each locality, a high proportion of the lowermost sandstone complex is exposed and crops out over a relatively short horizontal distance. The requirement that a rela tively large amount of the unit be exposed was considered necessary because it was considered inadvisable to deduce the nature of the whole from a small and possibly biased sample. Short lateral distance of exposure was specified to minimize a stratigraphic-geographic interaction at a single locality.
Relative freshness, the last of the major sampled- locality selection criteria, was required because of the radical diagenetic changes in mineral composition caused by prolonged weathering in this region. 25
Intra-locality Sampling Plans
Introduction
All the sampling plans, although varying slightly one
from another, were slight variants of a purely systematic
sampling plan. Part of the differences between the plans
reflects basic qualitative differences between the core
and the outcrop localities; differences between plans for
different outcrop localities are due more to the usual
restrictions imposed by a fixed total sample size and a
natural evolution of technique as the study progressed.
Core Sampling
The core (located in Section 35, T17S, R9W, and stored
at the Geological Survey of Alabama) represents an essen
tially complete record of about 3200 feet of upper Car boniferous detritus extending from the surface to the first occurrence of fhassive limestone. The entire core was
sampled at roughly uniform intervals (see appendix), so that the material overlying the lowermost sandstone complex was
sampled in addition to the complex itself.
The core is stored in boxes which are classified according to the order in which their contents were removed from the hole. The first few boxes for instance are all
labelled "core 1" indicating that their contents all came
from the first, uppermost, core barrelful of material? and
are labelled additionally according to relative stratigraphic position within the core barrel. Since the contents of a
single core barrel varied from less than ten feet to fifty
feet in length, these were contained in as few as one or as many as four individual boxes.
The sampling of the core consisted of opening one box
from every fourth core barrelful. In some instances, the
scheme was slightly modified because of operational problems.
The selection of the particular box containing a portion of the entire core-barrel was made purely on the basis of ease of access in the core library.
Samples were selected from each box on the basis of visual differences (e.g., one sample was taken from each different-appearing rock type). These differences were apparently due to variation in color, grain size, and internal structure. The subjective criteria for selection of different rock types were so defined that any and every possible megascopic difference would be represented among 27 the samples. The samples from the core (numbering over 50) thus represented estimates of the maximum spectrum of mega scopic variation at roughly uniform stratigraphic intervals.
Sampling at Outcrop Localities
The samples collected from the outcrop localities are more coarse grained than most of the core samples because finer grained sediments are less resistent to processes of surficial weathering. The better ejqposed and preserved coarser sediment (coarse silt and sand) was sampled at roughly uniform intervals vertically at each outcrop (see appendix). A few samples collected at some localities represented sediment that appeared markedly different than the rest, even if it occurred in minor amounts (such as the rare greywacke beds present in the northern outcrops).
Again, sediments in bored zones and "mud flows" were not used in the collection of thin section data — even when such samples were sectioned.
Thin Section Technique
The samples were thin-section perpendicular to bedding.
Data was collected from within visually homogeneous units within the thin section in order to reduce intra-sample
p? / si- variability and to free the estimates from the influence of the ratio of thin section size to homogeneous unit size
(Ehrlich, 1964). Layered thin sections therefore yielded, in many cases, more than one set of data, each set repre- senting a separate layer. Composition and size estimates were obtained from Chayes (1949) point-count traverses parallel to bedding. Grain size was estimated by calcula ting the mean of ten apparent long axes (converted to phi) of quartz grains. Composition estimates were obtained by evaluation of 25 points on a Chayes traverse. VII
OBSERVED MINERAL SPECIES
Thin section study shows that the major constituents
(totaling more than 90%) of the lowermost sandstone complex
are quartz and "greenschist detritus" with minor amounts of
feldspar, chert, and "heavy" minerals.
Quartz occurs as angular to subangular grains
exhibiting the total range of extinction patterns from
simple to patchy (Krynine, 1950). Micaceous inclusions
are common and in some cases were so abundant (constituting more than half) that the particle was classed as a green
schist fragment.
"Greenschist detritus" is a term that covers the many micaceous products of a disintegrated greenschist.
These include polymineralic fragments of schist and phyllite (generally composed predominantly of chlorite)
as well as chlorite flakes. Biotite and chloritized-
epidotized igneous rock fragments (of relatively rare
occurrence) were also included in this category.
Three feldspar varieties can be distinguished:
29 untwinned albite, twinned sodic plagioclase, and
orthoclase. The untwinned albite, comprising up to
10% of the total composition, is difficult to distinguish
from quartz when occurring as unweathered grains in
thin section. It is often strained and exhibits complex
extinction patterns often thought to be characteristic
of quartz. Examination of thin sections of the Hillabee
Schist from Clay County, Alabama, an igneous roclc that has undergone retrograde metamorphism and containing
similar albite varieties, aided in the identification
of this feldspar in the sediments. The predominance
of this feldspar variety, among the feldspars present,
was confirmed by examination of x-ray diffraction
patterns from several samples. The presence of this
species of feldspar is not unexpected since untwinned
albite is a common product of retrograde metamorphism of
more calcic feldspars in greenschist complexes. Twinned
plagioclase and orthoclase was judged to be highly sodic
on the basis of relative refractive indices and the
narrowness of twin lamellae. The orthoclase, stained
with sodium cobaltic nitrate, was sparsely present in most
samples. Rather coarse-grained chert was observed in most sections, but was not abundant enough to much affect the point counts. The heavy mineral suite, described in detail by Bryan (1963) contains garnet as the most abundant non-chloritc constituent. VIII
COMPOSITIONAL PATTERN OF THIN SECTION DATA
Areal Compositional Variation in the Lowermost Sandstone Complex
Removal of Grain Size Effect on Composition
If a group of samples cover a wide enough range of both compositional values and grain sizes, a functional relation ship between size and composition can be determined. The compositional deviations of observed sample values from those predicted at a particular grain size by the function are independent of the grain size affect on composition.
This compositional deviation value then varies predominantly in response to tectonic intensity factors, since other effects were minimized by sampling techniques.
Rather than determining such a relationship for each
sample locality and then comparing the resulting functions, the functional relationship was calculated only from the core samples. The core function was the least squares line of best fit for the relationship between grain size
32 33 and "quartzoseness"^ (figure 5). The relationships between the sample-point arrays from each locality to each other and to the core function can be observed graphically. The core function itself, as will be seen later, represents an average of many different, but roughly parallel functions generated at different levels in the core.
Regional Pattern of Compositional Deviations
The scatter plots from each locality generally produced a pattern that was parallel to the core function but not coincident with it (figure 6). The arrays from localities
A, B, and C (figure 3) overlap one another almost completely
(figure 7) and define a function about 20% more quartzose for all grain sizes than that of the core. Although some samples from locality D fall in with the scatter of sample points from A, B, and C; others fall well below that group ing. Samples from locality E and from the lowermost sand stone complex in the core also array in patterns less quartzose
^'Quartzoseness" is actually the sum of all the "three- dimensional framework" minerals — quartz, feldspar, and chert. Quartz is by far the most abundant constituent. Quartzose- ness, representing mechanically resistant minerals, bears an inverse relationship to the abundance of greenschist detritus, a category containing mechanically weak mineral species with predominantly layered crystal structures.
r Ficrure 5. Relationship between Quartzoseness and Grain Size of Core Samples Core ofSize Grain and Quartzoseness between Relationship Ficrure5.
QUARTZ CONTENT 10095-25 0 5 - 5 6095-1 OE TSAOS COUNTY TUSCALOOSA CORE: Aprn Ln Ai o Quartz) of Axis Long (Apparent RI SIZE,SIZE GRAIN 100%-251- • » « 100% - 25 r* • Blount Mtn. Outcrop A Outcrop B • • . 8 0 % - 2 0 - g«0% -l5
2 0 % - 5
GRAIN SIZ£. ♦ GRAIN SIZE. +
Outcrop D
z C 3% - 15
2 0 % - S
GRAIN SIZE. + GRAIN SIZE. •
100%-25 p • Q t t m Sfeinf* Hwy. Outcrop E C ore . 8 0 % - 2 0 -
g AO fc- 10
GRAIN SIZE. ♦ GRAIN SIZE. 8
a '* SIZE. ♦
Figure 6. Relationship between Quartzoseness and Grain Size of Samples from Localities within the Lowermost Sandstone Complex
35 il Be. a Core, Upper Bed,
* 6 0 % - 1 5 * 6 0 % -1 5 •00
GRAIN SIZE, 0 GRAIN S IZE, •
IS U , B lo u n t U t a . , 0 C o re , L o ererm o et Be, * Send M ta . O Oreen flprtnf* IHrjr, •o
p 40% - 10
GRAIN SIZE. • GRAIN SIXE. ♦
5 60% -15
y 40% - 10
20% - 5
GRAIN SIZE. ♦ GRAIN...SIZE, ♦
Figure 7. Comparison of Quartz-Grain Size Relationships between Localities within the Lowermost Sand stone Complex
36 37
at any grain size than most samples from A, B, and C. In
addition, locality E, southernmost sampled locality, appears
to be on the whole least quartzose of all. The large amount
of overlap of sample' arrays from A, B, and C and also of
those from locality E and the core indicates little variation
along east-west directions.
These relationships between sampled localities corrobo
rate the field-derived pattern of compositional variation
detected in the sandstones of the lowermost sandstone complex.
The data, cleared as much as possible of extraneous effects,
still reflects compositional variation expected from the
effects of transport from a southern uplifted greenschist terrane. A similar analysis of the pattern of compositional deviations with stratigraphic position in the core yields data concerning chronologic changes in the rate of tectonic
intensity as recorded in northern Tuscaloosa County.
The Record of Changes in Tectonic Intensity Within the Core
The complete core represents the total detrital record
available at a single locality of the changes in tectonic
intensity associated with the southern source terrane. This
information, coupled with the data concerning lateral 38 variation reported in the preceding section, allows con struction of a crude model of stratigraphic variation within the basin.
The deviations of the core samples from the values pre dicted by the core function exhibit a trend of increasing quartzoseness with depth (figure 8). This pattern reflects a history of increasing tectonic intensity with time. The youngest samples from the core indicate neither a slackening of rate nor the ultimate degradation of this positive fea ture. At last glimpse the system is in robust growth.
That removal of the grain size effect was necessary is indicated by figure 9 where the observed trend is almost obliterated by the addition of the component of compositional variation due to the variation in grain size. Figure
FEET BELOW LAND SURFACE B . Deviations of Core Samples from Least Squares Line with Line Squares Least from Samples Core of Deviations B. 2,000 3,000 1,000 3,200 Stratigraphic Position Stratigraphic -40S -40S UR Z DVAIN RM Y-24.1-3.2x DEVIATION FROMQUARTZ, • • * • - 20 0 3 * • • • • • % • • • • 0 * <>• • %
o \ o • • • 0 40S 20* \ UCLS COUNTY TUSCALUSA v . • k •. • * 5
CORE: 10
Figure
FEET BELOW LAND SURFACE ! 9 . Total Quartz-Grain Size Relationship of Core Samples with Samples ofCore Relationship Size Quartz-Grain Total 9. 2,000 3,200 3/000 ,0 • • h 1,000 Stratigraphic Position Stratigraphic “ I • • • • • • • • 20 U RZ RELATIVEQUARTZ, ABUNDANCE % • • 0 6S 0 100H 80S 60S 40* • • • • • • • • • • • •
15 20 20 15 • 1 • • • • • • • • * UCLS COUNTY TUSCALUSA • • ^ sir ■^5
•• CORE: 7
I IX
CORROBORATION OF OBSERVED LATERAL AND VERTICAL PATTERNS IN OTHER PARTS OF THE DETRITAL VOLUME
The compositional pattern, observed in the core, of
decreasing quartzoseness upwards documents the later por
tion of the record of the accelerating emergence of a
detrital source terrane. A similar, lateral, pattern of
decreasing quartzoseness from north to south within the
lowermost sandstone complex indicates the direction in which
the source was located. Extrapolation of these two lines of
evidence permits construction of a rough model of patterns
of variation to be expected in sediments both above and
below the sandstone complex. Observed patterns include a
north to south limestone to shale facies change in sediments below the complex, a southwards increase in sand content in
sediments overlying the complex, presence of a southern con
glomeratic facies intertonguing with northern sands, and
the very low quartzoseness of sandstones from the Tuscaloosa
area.
41 4 2
The Basal Limestone to Shale Facies change
The Gaspar and Bangor limestones, uppermost Mississip-
pian carbonates in northern Alabama, are reportedly
replaced by Floyd Shale south of an east-west line drawn
near Birmingham (Butts, 1910, 1927). Butts, himself,
interpreted this pattern as representing the influence of a
southeastern source — an interpretation not greatly at
variance with the one presented here.
Facies Change in the Jagger-Pratt Interval
As shales overly limestones at the base of the detrital
sequence, so do greywacke sandstones interbedded with silt-
stone overly the orthoquartzitic phases of the basal sand
stone complex. Massive sands are, however, less common in
this interval in the Birmingham area, although more common
farther south.
An instance of this southwards coarsening can be
observed in the interval between the Jagger coal bed (lowest
economically valuable coal) and the Pratt coal group (next higher-valuable coal group). This interval, about 500 feet
thick, changes from a poorly sorted grey siltstone with occasional interbeds of greywacke sandstone near Birmingham
to predominantly greywacke sand in the vicinity of 43
Tuscaloosa, about fifty miles to the southwest.
Low Quartzoseness of Sandstone Prom the Vicinity of Tuscaloosa
Surface and shallow core samples from the Tuscaloosa area are stratigraphically higher and located farther south than any group of samples heretofore discussed. They are, on the whole, much less quartzose than any of the other sample groups (figure 7) — a result ejqpected from their location and stratigraphic position. In addition, thick chlorite books occur in noticeably greater amounts than in samples collected farther north.
The Southern Conglomeratic Facies
Several thousand feet of conglomerate and conglomeratic sandstone are reported to cap the detrital sequence near the southern limit of outcrop (Butts, 1927). The lateral vari ation of a prominent conglomerate bed near the base of this sequence, the Straven Conglomerate, has been described by
Butts and checked by the author. The unit is principally composed of quartzite cobbles and pebbles but includes frag ments of greenschist and chert.
Butts reports: "The Straven is a very coarse 44 conglomerate 40 feet thick or thereabouts. ...The pebbles diminish in number and size northwards, and in the area southwest of Henryellen in the Birmingham Quadrangle the bed is a sandstone that has a few small pebbles scattered through it. The Straven Conglomerate is the basal bed- of a con glomerate series of the same kind, which reaches a thickness of 200 feet, making the uppermost part of the Pottsville formation in the southeastern part of the Cahaba coal field west of Montevallo. The source of the material was probably still farther southeast." (Butts, 1927, p. 14).
Thus a thick conglomeratic facies caps the sequence at the southern limit of outcrop and intertongues, at least in part, with the more northern sandy facies. SUMMARY AND CONCLUSIONS
The exposed sequence of detritus in the Black
Warrior Basin thickens southwards. Apace with, this thickening, new petrologic elements are introduced that are, at least in part, facies of rock types observed farther north.
The key to understanding the observed patterns of variation in the basin was data on the related variations of the two most abundant compositional components - quartz and greenschist detritus obtained from a widespread array of localities within the lowermost sandstone complex. The compositional data, cleared of extraneous effects, established the presence of a gradient of decreasing quartzoseness southwards; and, on the other hand, presented no evidence for a similar trend along directions oriented more nearly east-west.
Examination of a core from northern Tuscaloosa County
in a like manner resulted in detection of a similar pattern, but with quartzoseness decreasing upwards. 46
These lines of evidence are interpreted as reflections of the influence of a southern greenschist terrane being uplifted at an increasing rate. Other lines of evidence, from other portions of the detrital mass substantiate these conclusions (see cross-section figure 10). The first pulses of uplift are detected by observation of the replacement of Upper Missippian limestones by shales south of Birmingham. Above the lowermost sandstone complex, the sediment coarsens southwards, culminating in a conglomeratic sequence observed in the southernmost outcrops. Samples of sandstone from the Tuscaloosa area are, as expected, much less quartzose than those from any other sample group collected at more northern localities.
All of the data point to an uplifted greenschist terrane as the source of the bulk of the detritus observed in the basin. No variational gradients have been detected at high angles to present Appalachian trends.
This situation is interpreted to be a manifestation of a tectonic activity along Ouachita trends beginning in late Mississippian time. The inauguration of
Appalachian uplift is considered to be distinctly younger See Figure 10 "In Pocket" iue1. ot-oSuhGnrlzdCosScintruh the through Cross-Section Generalized North-to-South 10. Figure 8000'*— 700Q1—
6000' — 6000' DEPTH, feet h- 'h 0 0 0 4 h- 'h 0 0 0 5 3000' 3000' 00h- 2000'h 1000' - h - h Detrital Volume Detrital ^ O ^ c * *A * c? ^ O * O ' Facies 2' Conglomeratic • O r^ak. < Gre^wacke.^ . 0 • O . ^ ° ° A & • • & ° ^ c* o ' o
o 1 &
• » * j- o 0 * o ,, ; ‘O' c© A ) 9 * * • o O Q~ s ° O i ® ■ *'* 0/s V ° C v 0 O r ■ ° a * I t> . ' » • : «, v .. - Greywacke a 0 . i . «=> • O crf> • .’ • O ^ • o «® 0 ' \ ~ Silty Facie 1 ^ • . •— •■•— •• • k . : * . b a 0» * * - o
0 & ■ _ • ' a ftp y _ „• V ‘:= ••'.— * -r ; • * _ & -4. • . . * . •; lo ** . — — ° • rv^Orttvo Greywacke Sandy
s e Location D 1 Location E 2 Pottsville fm. 1 Pottsville fm. 2 Parkwood fm. 3 Floyd shale Formal stratgraphy nomenclature after C. Butts, 1927. D i v .'. - - Greywacke • ' Silty Facies.
D i ~ > * m m m m qbartziijicSandvFacies
Location A 1 Pottsville fm. 2 Boyles ss. member p.f. Location D 3 Pennington shale 1 Pottsville fm. 4 Bangor limestone
stratgraphy nomenclature C. Butts, 1927. since its' effect is not reflected in the sedimentary patterns yet did structurally deform the rock body.
Further, the Ouachita structural trend must have extended farther east than now has been determined in order to produce the observed patterns. Thus, the later Appalachian folding and uplift quite likely cross-cut this earlier tectonic trend. SELECTED REFERENCES
Bryan, jack H. 1963 A Petrologic Study of the Pottsville
Formation at Holt Dam Site, Alabama;
M.S. Thesis, Department of Geology,
University of Alabama.
Butts, Charles 1910 Birmingham Folio, Geologic Atlas of
the U.S.; U.S. Geological Survey.
1927 Bessemer-Vandiver Folio, Geologic
Atlas of the U.S.; U.S. Geological
Survey.
Chayes, Felix 1949 A Simple Point Counter for Thin
Section Analysis; American Mineralo
gist, vol. 4; p. 1-11.
Ehrlich, Robert 1963 Evidence on Relative Ages of the
Appalachian and Ouachita Structural
Trends (Abs.); Geol. Soc. of Am.
Spec. Paper 82.
1964 The Role of the Homogeneous Unit in
Sampling Plans for Sediments; Jo urn.
Sed. Pet.; vol. 34, no. 2, p. 437-439,
49 50
1964 Some Ostracods From the Pennington
Shale of Alabama; Geological Survey
of Alabama Circular 29; University,
Ala.
1964 Field Trip Guidebook to the Potts
ville Formation in Blount and
Jefferson Counties, Alabama; Alabama
Geol. Soc. Guidebook No. 1; Univer
sity, Ala.
1965 ( with J. C. Ferm) Tectonic
Chronology of Pennsylvanian Border
lands (abs.); Meetings of the
American Association of Pet.
Geologists; New Orleans, La.
Ferm, John C. 1957 Petrology of the Kittaning Forma
tion near Brookville, Pa.; Ph.D.
Dissertation; Department of
Mineralogy; Pennsylvania State Univ.
State College, Pa.
1964 (with Williams, E. G.) Sedimentary
Facies in the Lower Allegheny Rocks
of Western Pennsylvania; Jour. Sed.
Pet.; vol. 34, no. 3; p. 610-614. 51
King, Philip B. 1951 The Tectonics of Middle North
America; Princeton University
Press; Princeton, N.J.; p. 123-124.
1961 The Subsurface Ouachita Structural
Belt East of the Ouachita Moun
tains; in The Ouachita System, ed.
by Flawn; Univ. of Texas Pub.
no. 610; p. 83-97.
Krynine, Paul D. 1941 Paleogeographic and Tectonic Signi
ficance of Greywackes (abs.); Bull.
Geol. Soc. Am.; vol. 52; p. 1916.
1941 Paleogeographic and Tectonic Signi
ficance of Sedimentary Quartzites
(abs.); Bull. Geol. Soc. Am.;
vol. 52; p. 1915-1916.
1942 Provenance versus Mineral Stability
as a Controlling Factor in the Com
position of Sediments; Bull. Geol.
Soc. Am.; vol. 53, p. 1850-1854.
1948 The Megascopic Study and Field
Classification of Sedimentary Rocks;
Journal of Geol.; vol. 56, no. 2;
p. 130-165. 52
1950 Microscopic Morphology of Quartz
Types? Proc. 2nd Pan American
Congress of Mining Engineering and
Geology? vol. Ill, 2nd Comm. v.
35-49, Petropolis Brazil; Oct., 1946.
Kummel, Bernhard 1961 History of the Earth, W. H. Free- »! man & Co., San Francisco, Cal.y
p. 116.
McCalley, Henry 1886 On the Warrior Coal Field? Special
Report no. 1, Geological Survey
of Alabama, University, Ala. APPENDIX
SAMPLE LOCATIONS AND RAW THIN SECTION DATA 54
LOCALITY A
Location: S34, T13, R3W; Interstate Hwy. 65; Blount Co., Alabama
Thin Section Quartzoseness Grain Size # Counts/25 %
A10 25 100 1.5 A20 20 100 2.4 A21 21 84 2.7 A40 21 84 1.8 A50 23 92 2.1 A51 19 76 4.6 A70 22 88 2.2 A71 22 88 2.0 55
-P'l J * q »o{ r*/f • H i n .
- PlXX
T --TT 1 -PHVfptsr /•*' ■ J l. p //»> puj - 7
LOCALITY B
Location: T13S,R3E, U.S. Hwy. 231 at Blount Mountain '
Thin Section Quartzoseness Grain Size # Counts/25 %
A509 16 64 3.3 A5010 23 92 1.6 A5011 20 80 1.6 £118 23 92 1.4 P122 16 64 4.3 P124 19 76 2.8 P132 13 52 2.7 P133 22 88 2.7 P135 20 80 3.7 P137 15 60 4.0 P1372 17 68 3.3 56
-3L -Pilfaijtk PlXOt Ptzt - fii* - f i t * * - T , | -/»*** LOCALITY C Location: TllS, R5E; U.S. 431, North of Gadson near Rock- ledge, Alabama Thin Section Quartzoseness Grain Size # Counts/25 % A610 8 32 3.0 A611 13 52 2.3 A620 21 84 2.6 A621 23 92 2.3 A622 25 100 1.2 A624 22 88 2.0 P117 23 92 1.5 P120 18 72 3.3 P121 23 92 2.6 P125 16 84 1.9 57 * p m ■ Pn/1/jP/Vf ■ m i P i V 3 r t 3 i P/Vx p m LOCALITY D Location: T15S, RlW; Ala. Hwy. 79, near Pinson, Alabama Thin Section Quartzoseness Grain ; # Counts/25 % P138 .19 76 2.5 P139 20 80 2.0 P140 16 64 2.3 Pi 41 16 64 2.8 P142 17 68 2.0 P143 16 64 1.5 P144 21 84 2.1 P145 20 80 1.7 P146 16 64 1.7 LOCALITY E Location: T18S, R12E; Ala. Hwy. 149 (“Green Springs Hwy."); Birmingham, Alabama Thin Section Quartzoseness Grain Size # Counts/25 % P100 21 84 1.9 PI 01 20 80 2.2 P102 22 88 2.0 PI 04 13 52 2.8 P105 10 40 3.4 PI 06 17 68 2.4 P107 18 72 2.1 PI 08 13 52 2.9 P109 16 64 2.8 P110 15 60 2.7 Pill 18 72 3.5 P112 17 68 2.8 59 - C (lOjCUt C . 7 » o - £ ?» 9 C 7V/ 7J*ft - O/P CORE Location: S35, T17S, R9W, Tuscaloosa Co., Alabama Thin Section Quartzoseness Grain Size # Counts/25 % C620 19 76 1.6 C6211 15 60 3.0 C6212 11 44 4.7 C6213 17 68 3.9 C660 22 88 1.6 C661 23 92 1.5 C7001 20 80 1.8 C7002 3 12 5.7 C730 6 24 6.0 C740 19 76 2.5 C741 18 72 2.8 C750 22 88 1.8 C790 25 100 1.7 60 DATA FROM THE ENTIRE CORE Location: S35-T17S-R9W Tuscaloosa Co., Alabama Depth, Thin Section Quartzoseness Grain Size, feet # Counts/25 % l—l 1 l—l o 40-57 o 13 52 4.9 C 102 5 20 6.3 C 11 14 56 2.0 201-220 C 1021 19 76 2.6 C 1022 8 32 5.0 C 103 9 36 5.3 232-245 C 1411 11 44 1.6 C 1412 12 48 1.6 C 142 17 68 1.5 371-396 C 1811 17 68 1.5 C 1812 0 0 6.5 466-511 C 220 7 28 5.1 C 222 13 52 1.9 622-672 C 2601 8 32 3.6 C 2602 5 20 4.0 C 261 10 40 4.8 C 2621 4 16 4.9 C 2622 4 18 5.8 821-871 C 300 10 64 2.2 C 3011 2 8 5.2 C 3012 10 64 3.2 C 3013 6 24 4.6 1009-1059 C 340 14 56 2.8 C 3411 15 60 3.1 C 3412 6 24 5.6 C 3421 6 24 4.0 C 3422 3 12 5.1 C 3423 13 52 4.0 61 Depth, Thin Section Quartzoseness Grain Size, feet # Counts/25 % 1155-1205 C 3701 16 64 4.3 C 3702 17 68 4.5 C 3703 22 88 4.9 C 3721 12 48 4.2 C 3722 19 76 4.7 C 3723 15 60 3.8 C 3731 8 32 5.0 C 3732 11 44 4.4 C 3733 19 36 4.5 1552-1602 C 460 15 60 3.3 C 461 5 20 5.8 C 462 16 64 4.4 C 463 8 32 4.3 1750-1762 C 5011 0 0 6.8 C 5012 14 56 3.6 1906-1940 C 540 21 84 1.8 C 542 0 0 5.8 2059-2106 C 5801 19 76 3.2 C 5802 19 76 3.2 C 581 16 64 1.5 C 583 3 12 7.2 2301-2351. C 620 19 76 1.6 C 6211 15 60 3.0 C 6212 11 44 4.7 C 6213 17 68 3.9 2451-2497 C. 660 22 38 1.6 C 661 23 92 1.5 2556-2606 C 7001 20 80 1.8 C 7002 3 12 5.7 Lower most sandstone most Lower 2703-2753 C 730 6 24 6.0 62 Depth, Thin Section Quartzoseness Grain Size, feet # Counts/25 % 2753-2794 C 740 19 76 2.5 4J C 741 18 -72 1.8 10 3032-3078 C 8221 17 68 3.1 C 8222 18 72 3.1 3126-3174 C 850 2 8 6.4 C 8502 12 48 4.6 C 8503 18 72 5.2 VITA Robert Ehrlich was born March 4, 1936 in St. Paul, Minnesota; the son of Max and Eva Ehrlich. There, he attended Richards Gordon elementary school (named for an early trafficker with the Indians) and Central High School. Upon graduation from high school in 1954, he entered the University of Minnesota; from which he earned, in 1958, a Bachelor of Arts degree with a major in geology and a minor in physics-geophysics. While at Minnesota, he was a member of "The Cerebrals" — the university champion quiz bowl team of 1956 (and runner-up in 1957), treasurer of the Geology Club, and pitcher for the Geology Club slow-pitch soft ball team. After graduation from Minnesota, he entered the graduate school of Louisiana State University as a candidate for a M.S. degree in geology; receiving that degree in 1961. His masters' thesis was entitled "Petrography of Some Wilcox Sediments at Grand Ecore, Louisiana." He thereupon entered the Ph.D. program in the department of geology at L.S.U. At L.S.U. he has held graduate teaching asSistantships 63 and an instructorship, taught at the Colorado summer camp, and was the recipient of fellowships sponsored by the Pan American Oil Company (1960) and the Socony Mobil Oil Company (1960-1962). He is a founder of the L.S.U. Flat Earth Society and gave the inaugural talk of the Gilbert Harris Club. He accepted a position in 1965 as assistant professor of geology at Michigan State University starting in Septem ber, 1965. His research interests include grain properties of detri- tal sediments, tectonic sedimentology, and geometries. He has had the good fortune to be married to the former Sarah Virginia Turnley since November, 1961. EXAMINATION AND THESIS REPORT Candidate: Robert Ehrlich Major Field: Geology Title of Thesis: The Geological Evolution of the Black Warrior Detrital Basin Approved: 'ajor Professol/and Chairman Dean of the Graduate School EXAMINING COMMITTEE: Date of Examination: July 2, 1965