Preliminary Report on the Uranium Favorability of the Hartselle Sandstone and the Pottsville Formation in the Coosa Basin, Alabama

GJBX-83(78)

PRELIMINARY REPORT ON THE URANIUM FAVORABILITY OF THE HARTSELLE SANDSTONE AND THE POTTSVILLE FORMATION IN THE COOSA BASIN, ALABAMA

ndi Field Engineering Corporation Grand Junction Operations Grand Junction, Colorado 81501

June 1978

PREPARED FOR THE U.S. DEPARTMENT OF ENERGY GRAND JUNCTION OFFICE UNDER CONTRACT NO. EY-76-C-13-1664

metadc784588 This report was prepared as an account of work sponsored by the United States Govern- ment. Neither the United States nor the United States Department of Energy, nor any of their employees, nor any of their contractors, subcontractors, or their employees, makes any warranty, express or implied, or assumes any legal liability or responsibilityfor the ac- curacy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. I I GJBX-83(78)

PRELIMINARY REPORT ON THE URANIUM FAVORABILITY OF THE HARTSELLE SANDSTONE AND THE POTTSVILLE FORMATION IN THE COOSA BASIN, ALABAMA

Erik H. Schot and H. Michael Penley

BENDIX FIELD ENGINEERING CORPORATION Grand Junction Operations Grand Junction, Colorado 81501

June 1978

PREPARED FOR THE U.S. DEPARTMENT OF ENERGY GRAND JUNCTION OFFICE UNDER CONTRACT NO. EY-76-C-13-1664

CONTENTS

Page

Summary ...... 1

Introduction ...... 2

Purpose ...... 2

Location ...... 2

Previous and present studies ...... 2

Geology ...... 4

Stratigraphy ...... 4

Major rock units under consideration ...... 4

Hartselle Sandstone ...... 4

Pottsville Formation ...... 4

Structure ...... 10

Procedures ...... 10

Literature study ...... 10

Field investigations ...... 10

Analytical investigations ...... 10

Uranium favorability ...... 11

Evidence of uranium mineralization ...... 11

Favorability characteristics ...... 11

Hartselle Sandstone ...... 11

Pottsville Formation ...... 12

Possible sources of detritus and uranium ...... 12

Hartselle Sandstone ...... 12

Pottsville Formation ...... 13

Results ...... 0.9..... 13

iii CONTENTS (continued)

Page

Radiometric surveys ...... 13

Petrography ...... 13

Chemistry...... 13

Conclusions ...... 14

Bibliography...... 17

ILLUSTRATIONS

Figure 1. Generalized geologic map of the Coosa basin, Alabama, and adjacent areas ...... 3

Plate 1. Locations of samples, scintillometer readings, and subbasins in the Coosa basin, Alabama ...... In pocket

2. Generalized stratigraphic section of the Coosa basin, Alabama ...... 0. 0. 0. 0. 0. 0. 0. . . . In pocket

TABLES

Table 1. Paleozoic rock units of the Coosa basin and their equivalent uranium contents ...... 5

2. Results of petrographic and chemical analyses ...... 6

iv SUMMARY

The Hartselle Sandstone and the Pottsville Formation in the Coosa basin were studied to determine if the units appear favorable for the occurrence of uranium deposits and if a more detailed investigation of the area is warranted. The study involved a literature synthesis, field work, and sampling of rock outcrops for petrographic and chemical analyses.

The study indicates that the Hartselle Sandstone and the Pottsville For- mation possess characteristics favorable for uranium mineralization to have occurred. Alteration features and evidence of secondary mineralization at surface exposures suggest that both the Hartselle and Pottsville may possess additional favorable characteristics in the subsurface.

Because of extensive leaching and oxidation of Hartselle and Pottsville exposures, the results from chemical analyses for U3 0, and scintillometer surveys may not be an accurate indication of favorability for uranium occur- rences in the area. Low chemical uranium values obtained from fluorometric analyses as well as the low radioactivity observed in the field do not nec- essarily indicate a low potential for uranium mineralization at depth.

1 INTRODUCTION

PURPOSE

The purpose of this preliminary geologic study was to evaluate the Paleo- zoic rock units exposed in the Coosa basin of Alabama as potential uranium hosts. The study evolved as a result of a report by Dennison and Wheeler (1972) on the potential as uranium host rocks of fluvial-deltaic, Precambrian through Cretaceous strata in the southeastern United States. The Mississippian Hartselle Sandstone and the Lower Pennsylvanian Pottsville Formation were given prime consideration on the basis of the findings and recommendations of Stow (1955), Ferm and Galloway (1971), and Dennison and Wheeler (1972).

LOCATION

The Coosa basin lies within the Valley and Ridge province along the southeastern margin of the Appalachian Carboniferous plateau. The basin trends northeastward and extends from southwestern Shelby County, across St. Clair County, into northwestern Calhoun County in north-central Alabama, and occupies approximately 260 sq mi in the eastern half of the Birmingham quadrangle (U.S. Geol. Survey, 1969; P1. 1; Fig. 1).

PREVIOUS AND PRESENT STUDIES

Previous geological investigations of the Coosa basin pertain to coal, ground water, and clay resources (Gibson, 1895; Prouty, 1909; Butts, 1925; Jones, 1925, 1929; Johnston, 1933; Rothrock, 1949a, 1949b; Causey, 1963; Culbertson, 1964; Clarke, 1968) and to the general geology, stratigraphy, and structure of the basin (Gibson, 1895; McCalley, 1897; Butts, 1927; Rothrock, 1948, 1949a, 1949b; Causey, 1963; Culbertson, 1963; Cooper, 1964; Carrington, 1965; Mueller, 1965; Thomas, 1965a, 1965b, 1967, 1972a; Ferm and Ehrlich, 1967; Wanless, 1967; Clarke, 1968; Drahovzal and Neathery, 1971; Ferm and Galloway, 1971). Geologic maps of the Coosa basin have been prepared by Prouty (1912), Butts (1927), Rothrock (1948, 1949a), and Clarke (1968).

The Geological Survey of Alabama conducted a study of the uranium potential of the Pottsville Formation and of the Tuscaloosa Group in central Alabama as part of the U.S. Geological Survey's Uranium and Thorium Resource Assessment and Exploration Research Program for FY 1976 (Finch, 1975; Gilbert, 1976). The study included geologic mapping, radiometric surveying, and stream-sediment sampling. Seventy stream-sediment samples were collected from the Coosa basin and submitted for chemical analysis to the Savannah River Laboratory as part of the hydrogeochemical and stream-sediment reconnaissance surveys being conducted in connection with the U.S. Energy Research and Development Administra- tion's National Uranium Resource Evaluation (NURE) program (Finch, 1975; Savannah River Lab., 1976).

2 R.2 E.I R.3 E.

010 M iles .- .---. .--- ...... - ...... : .- ......

...... -- *-**.**... .- *'- . -"-... .

- - -- A LA BAM A - -INDE- - -.- X MA P

BASIN BOUNDARY

-:-::- -- -PENNSYLVANIAN

SMISSISSI PPIAN

SILURIAN AND DEVONIAN UNDIFFERENTIATED

U THRUST FAULT CAMBRIAN AND ORDOVICIAN UNDIFFERENTIATED (Modified after Clarke, 1968)

Figure 1. Generalized geologic map of the Coosa basin, Alabama, and adjacent areas.

3 GEOLOGY

STRATIGRAPHY

Exposed rock units in the Coosa basin range in age from Late Cambrian through Early Pennsylvanian. Plate 2 is a generalized stratigraphic section for the basin, Table 1 lists the Paleozoic rock units radiometrically surveyed for this study, and Figure 1 shows the generalized schematic geology of the area.

MAJOR ROCK UNITS UNDER CONSIDERATION

Hartselle Sandstone

The Hartselle Sandstone conformably overlies the Pride Mountain Formation (Mississippian) for a distance of 35 mi along a part of the basin's northwestern flank from Leeds northeastward to beyond Odenville (Thomas, 1965a). The Hartselle attains a maximum thickness of 189 ft near Odenville and pinches out laterally in Shelby County to the southwest and Calhoun County to the northeast.

The Hartselle is the thickest sandstone in the Mississippian rock sequence of the basin and consists of sandy, brown-weathering siltstone which grades upward into a light-gray, fine-grained, well-sorted, thin- to medium-bedded, laminated quartzose sandstone (Rothrock, 1949b). Locally, the Hartselle is calcareous and conglomeratic with clay-, shale-, and siderite-pebble conglomerates. Shale and shaly sandstone intercalations, which are in part carbonaceous and pyritic, occur throughout the Hartselle sequence (Thomas, 1972a). Petrographic analyses indicate that Hartselle sandstones are predominantly quartz arenites and subordinately feldspathic arenites, which are fine to medium grained and moderately to well sorted (Table 2).

The Hartselle Sandstone is thought to represent an interval of clastic sedimentation along a barrier-island complex (Thomas, 1972a). The pinching out of the Hartselle along the strike of the isopachous maximum in the Coosa basin (Thomas, 1972a, p. 3, Fig. 1, Pl. 10) is attributed to accelerated subsidence of the basin and concurrent disintegration of the barrier form. This subsidence or downwarping of the basin led to the development of gravity slides, such as those observed in Hartselle exposures along the railroad cuts east of Odenville.

Pottsville Formation

The Pottsville Formation unconformably overlies the Parkwood Formation of Mississippian age and occupies the central part of the basin. Until recently the contact between the Parkwood and Pottsville Formations was viewed as either regionally unconformable or gradationally conformable, because of the presence of localized scour and fills at its base (Thomas, 1972a). The Pottsville thickens from 5,000 ft at the northeastern end of

4 TABLE 1. PALEOZOIC ROCK UNITS OF THE COOSA BASIN AND THEIR EQUIVALENT URANIUM CONTENTS

Geologic eU* Number of series or Formation Lithology (ppm) locations

shale 12-31 38 siltstone (incl. red beds) 4-24 7 coal 17-22 2 29 1 Pottsville Formation underclay P l mcross-bedded sandstone 4-14 5 Z heavily leached, banded sandstone 2-12 6 Z sandstone 0-22 40 shale-pebble conglomeratic sandstone 7-19 2 quartz-pebble conglomeratic sandstone 0-22 4

Parkwood Formation shale 9-27 13 U,

shale 19-24 3 Floyd Shale carbonaceous shale 19-21* 1 mylonitized shale 17 1 Hartselle Sandstone sandstone 0-12 7 shale 14 1

shale 9-24 4 Pride Mountain Formation iron-oxide stained shale 9-14 4 (Gasper Shale) shale underlying iron-oxide stained shale 17 2

Fort Payne Chert cherty limestone 9-14 3

?Maury Shale shale 24 1 Chattanooga Shale shale 19-24 2 H Z Frog Mountain Sandstone sandstone 9-14 2

*Gamma-ray spectrometer. **Range in readings taken at single location. TABLE 2. RESULTS OF PETROGRAPHIC AND CHEMICAL ANALYSES

Oxide and trace element concentration Sample cU 30O P205 As Pb Se Mo no. J -Sample location Formation Lithology (ppm) (%) (ppm) (ppm) (ppm) (ppm)

18882 Loc. 1: Railroad cut 0.3 mi West of Helena matrix Lithic wacke _ I______4 18880 Loc. 1 Quartz wacke

18897 Loc. 1 Quartz wacke

18902 Loc. 1 Quartz wacke

18894 Loc. 1 Quartz arenite

18898 Loc. 1 a Quartz arenite

18901 Loc. 1 Ca Quartz arenite

O 18885 Loc. 1 Pottsville 00 Black chert C 0 clasts 18889 Loc. 1 Formation Semischist ON c 18893 Loc. 1 Phyllite

CU) 18881 Loc. 1 Leucocratic gneiss

18879 Loc. 1 Silicified rhyodacite porphyry

18891 Loc. 1 Silicified rhyodacite porphyry

18892 Loc. 1 Silicified rhyodacite porphyry

18896 Loc. 1 Silicified rhyodacite porphyry

18900 Loc. 1 Silicified rhyodacite porphyry

L 1 1 20395 Loc. 6: Yellow-Leaf Silty shale 3 3 8 4 Subbasin, cut along dirt road red 20396 Loc. 6 Ferruginous claystone 2 - 4 Nil 6 beds 20397 Loc. 6 Claystone 2 - 8 Nil 6

20398 Loc. 6 Lithic arenite 1 - 3 Nil 4 6

(See footnotes at end of table, p. 8.) TABLE 2. (continued)

Oxide and trace element concentration Sample cU3 0 P205 As Pb Se Mo no. -/ Sample location Formation Lithology (ppm) (%) (ppm) (ppm) (ppm) (ppm)

18071 Loc. -3: Yellow-Leaf Subfeldspathic lithic wacke subbasin, off paved road

18068 Loc. 2: Railroad cut Quartz arenite 0.3 mi north of U.S. route 280

18069 Loc. 2 Quartz arenite

18070 Loc. 2 Pottsville Quartz arenite

18886 Loc. 4: Quarry off State Formation Quartz arenite -2 - <1 Nil 1 <1 route 25 _1 1 18887 Loc. 5: Railroad cut 0.4 Quartz arenite 1 - 2 Nil 2 1 mi ESE of Brompton Shades

18888 Loc. 5 Quartz arenite 1 - '3 10 1 2 Sandstone

20394 Loc. 7: Cut off State Quartz wacke 2 - 3 4 2 Member Nil route 4, 0.5 mi ESE of Brompton |i 20393 Loc. 7 Contact zone Iron-oxide-encrusted zone 2 13 14 9 3

20392 Loc. 7 Parkwood Formation Shale 3 9 21 4 Nil

i i 18884 Loc. 8: Quarry off Quartz arenite 1 - 4 Nil 3 Nil dirt road 1.5 mi ENE of Odenville

18889 Loc. 8 Quartz arenite 2 - Nil Nil 2 1 Hartselle 18890 Loc. 8 Quartz arenite 1 - 2 10 2 <1 Sandstone 18885 Loc. 9: Road cut along Quartz arenite 1 - 3 10 3 <1 State route 174

20391 Loc. 9 Feldspathic arenite 2 - 1 14 13 5

20389 Loc. 10: Railroad cut Quartz arenite 2 - 1 Nil 11 5 east of Odenville

(See footnotes at end of table, p. 8.) TABLE 2. (continued)

Oxide and trace element concentration Sample cU308 P205 As Pb Se Mo (ppm) (%) (ppm) (ppm) (ppm) (ppm) no. Z Sample location Formation Lithology 3

20387 Loc. 11: Railroad cut Shale 3 - 10 Nil 8 3 east of Odenville

20386 Loc. 11 Pride Mountain Fm. Iron-oxide-stained zone 2 - 5 Nil 2 2 (Gasper Shale)

20399 Loc. 11 Shale underlying iron-oxide- 2 - 12 14 7 5 stained zone

20385 Loc. 11 Iron-oxide-stained zone 2 - 2 Nil 2 1

20383 Loc. 12: Railroad cut east of Odenville Ft. Payne Chert Cherty limestone 2 - 3 Nil 3 2

20384 Loc. 13: Railroad cut Shale 3 0.13 2 Nil 11 3 east of Odenville Chattanooga Shale

20382 Loc. 13 Phosphatic nodules 4 0.20 2 Nil 1 <1

20390 Loc. 14: Railroad cut Feldspathic arenite 3 - 1 Nil 5 3 east of Odenville Frog Mountain Ss. 18883 Loc. 15: Ingrams Quarry Quartz arenite 2 - Nil 10 5 1

1 Analytical and sample storage number.

2 Location numbers refer to Plate 1.

3 Petrographic analyses by R. S. Wegrzyn and D. R. Allen; nomenclature after Williams and others (1954).

4 Dash indicates measurement not determined. the basin to 7,500 ft at its southwestern end and consists of a sequence of conglomerates, sandstones, siltstones, and shales deposited in an alluvial and delta-plain environment (Ferm and Galloway, 1971). On the basis of lithologic differences, Rothrock (1949b) subdivided the Pottsville into a lower and an upper sequence (P1. 2).

The lower Pottsville sequence consists of 3,500 ft of red- and brown- weathering, lenticular sandstones, siltstones, and claystones; two conglomeratic sandstone members; and a few, very thin coal beds (Thomas 1972b). The base of the Pottsville is marked by a conglomeratic sandstone, the Shades Sandstone Member, a 190- to 500-ft-thick (Culbertson, 1964), thick-bedded to massive sequence of white to gray, friable, quartzose sandstones and scattered lenses and layers of quartz-pebble conglomerate that contains angular chert and shale fragments. According to Rothrock (1949b), irregular grains and interstitial fillings of kaolinitic material are plentiful in the Shades, in- dicating that originally the rock may have been arkosic or feldspathic. Clarke (1968) also describes the Shades as arkosic.

The Shades is overlain by a persistent 200- to 1,000-ft-thick interval of clay shales, siltstones, and fine-grained sandstones (Culbertson, 1964). This shale-siltstone-sandstone interval is overlain by the Pine Sandstone Member, a 200- to 500-ft-thick, thick-bedded to massive sequence of quartz- and shale-pebble conglomerates (Culbertson, 1964). The Pine is reported to be more conglomeratic than the Shades (Rothrock, 1949b) and to be arkosic as well (Clarke, 1968). Both the Shades and Pine Sandstone Members form the crests of successive ridges of many of the topographic highs in the Coosa basin, such as the Shoal Creek Mountains, Oak Mountain, Double Oak Mountain, and Double Mountain (P1. 1).

The upper Pottsville sequence consists of 2,000 ft of lenticular, fine- to medium-grained, medium- to thin-bedded, gray sandstones; light- to dark- gray siltstones; partly carbonaceous and locally pyritic, gray to black shales and claystones, which weather brown or reddish brown; and numerous relatively thick coal beds. It contains a higher proportion of sandstones than the lower Pottsville sequence (Ferm and Ehrlich, 1967).

Two conglomeratic sandstone members are known from the upper Pottsville sequence in the Coosa basin; these are the Wolf Ridge Sandstone Member and the Straight Ridge Sandstone Member. The Wolf Ridge Sandstone Member is 50 to 100 ft thick, and occurs approximately 1,200 ft above the Pine Sandstone Member; the Straight Ridge Sandstone Member is 20 to 150 ft thick, and occurs 4,500 ft above the Pine Sandstone Member (Jones, 1929; Culbertson, 1964).

Sandstones of the Pottsville are described as conglomeratic sandstones, feldspathic graywackes, and orthoquartzites (Ferm and Ehrlich, 1967; Ferm and Galloway, 1971). According to Ferm and Ehrlich (1967) and Dennison and Wheeler (1972), the sandstones tend to be more quartzitic toward the northeast part of the basin, and in the upper sequence contain volcanic detritus. Petrographic analyses showed that Pottsville sandstones include fine- to medium-grained, poorly to moderately well-sorted quartz arenites, lithic arenites, quartz wackes, and subfeldspathic lithic wackes.

9 STRUCTURE

The Coosa basin is an asymmetric, northeastward-trending, doubly plunging synclinorium. It lies within the Helena fault block, which is an upthrusted area bordered by northeastward-trending high-angle thrust faults: the Helena fault in the northwest and the Yellow-Leaf and Eden faults in the southeast (Fig. 1). Structurally, the basin conforms to the general trend of the Appalachians and is typical of the Valley and Ridge province. It is a com- posite of six northeastward-trending subbasins (P1. 1) separated by fault zones.

Along the northwestern limb of the basin, the rock units generally strike N. 350 to 450 E. and dip 100 to 700 SE. The rock units are faulted and folded more intensely within the plunging noses of the basin than along the northwestern limb. The southeastern limb of the basin has been truncated by high-angle thrust faults, such as the Yellow-Leaf and Eden faults (Fig. 1). This border faulting has dislocated the rock units and obscured their distribution, thickness, and stratigraphic position.

PROCEDURES

LITERATURE STUDY

A literature search and study of all available geologic references on the Coosa basin were conducted at the Geological Survey of Alabama in May 1976. These and other cited references on the general geology and geochemistry of uranium are listed in the bibliography.

FIELD INVESTIGATIONS

Field work was conducted in May and October 1976. Geologic reconnaissance, sampling, and scintillometer surveys were restricted to exposures of rock units along road and railroad cuts and in rock quarries (P1. 1; Table 1). To determine the probable source area of the Pottsville detritus, the Straven Conglomerate Member was studied and sampled just west of Helena (sample loc. 1, P1. 1) outside the Coosa basin.

ANALYTICAL INVESTIGATIONS

Petrographic (semiquantitative modal) analysis and mineral identification were performed on 37 rock samples. Chemical analyses for U3 08 ,. As, Pb, Se, and

Mo were performed on 25 rock samples; two of these were also analyzed for P2 05 . Locations of the sample sites are plotted on Plate 1. The analytical results are listed in Table 2.

10 URANIUM FAVORABILITY

EVIDENCE OF URANIUM MINERALIZATION

Anomalous radioactivity has been reported from asphaltic sandstones of the Hartselle in northern Alabama (Southern Interstate Nuclear Board, 1969; Ferm and Galloway, 1971) and from the basal Pottsville in north-central and northwestern Alabama (Stow, 1955). 0. E. Gilbert, Jr. (1976, personal commun.), reported uranium mineralization along the basal contact of the Pottsville with the Floyd-Parkwood in Marion County, northwestern Alabama. However, no anomalous radioactivity or uranium mineralization has been noted in surface exposures of either the Hartselle Sandstone or the Pottsville Formation in the Coosa basin.

FAVORABILITY CHARACTERISTICS

Characteristics that are prerequisite to the generation of a geochemical uranium cell in sandstones and conglomerates and that are commonly utilized as exploration guides for sandstone uranium deposits are discussed in a number of publications (Adler and Sharp, 1967; Finch, 1967; Grutt, 1972; U.S. Atomic Energy Comm., 1966, 1970). Although the favorability characteristics presented in these publications pertain primarily to clastic rock units exposed to the prolonged arid and semiarid climates of the western United States, the same characteristics are cautiously applied to the clastic rock units of the Coosa basin, which experienced prolonged exposure to a warm, humid climate.

Hartselle Sandstone

The Hartselle Sandstone possesses some characteristics that are associated with sandstones which host uranium:

1. It consists of marginal-marine sandstone and shale deposited in a barrier-bar and lagoonal environment.

2. The sandstones are predominantly quartzose and subordinately feldspathic, fine to medium grained, and moderately to well sorted.

3. Some shale and sha-ly sandstone -intercalations are reported to contain pyrite and carbonaceous material.

4. Exposures of the Hartselle commonly are stained by iron oxide and manganese oxide.

5. Basal Hartselle sandstones are underlain by shales of the Pride Mountain Formation.

11 Pottsville Formation

The Pottsville Formation possesses a number of characteristics that are associated with sandstones which host uranium:

1. It consists solely of continental, fluvial-deltaic conglomerates, sandstones, siltstones, shales, and coals (Dennison and Wheeler, 1972).

2. Conglomerates include quartz and flattened claystone or clay pellets and originally may have been arkosic. Conglomeratic sandstones at the base of the Shades are sparsely carbonaceous. Rothrock (1949b) reports carbonaceous claystone breccias from the upper Pottsville sequence.

3. Sandstones include quartz arenite, lithic arenite, quartz wacke, subfeldspathic lithic wacke, and in the upper sequence volcanic detritus.

4. Shale and siltstone intercalations are abundant; exhibit a discontinuous, intertonguing distribution; and in the upper sequence sometimes contain carbonaceous material and pyrite.

5. Coal beds and underclays of the upper sequence are reported to contain pyrite (Rothrock, 1949a, 1949b, Appendices).

6. Exposures of the Pottsville commonly are stained by iron oxide, and less commonly are bleached.

7. The contact between the basal conglomeratic sandstone..of the Pottsville and the underlying shale of the Parkwood locally is unconformable and characterized by scour and fill structures.

POSSIBLE SOURCES OF DETRITUS AND URANIUM

Hartselle Sandstone

The provenance of the detritus that composes the Hartselle Sandstone in Alabama has been subject to controversy (W. A. Thomas, 1976, personal commun.). One group of researchers advocates a northern provenance for the detritus in the area of eastern Canada and the northeastern Appalachians of the Maritime provinces with sediment transport through the Illinois basin by a southwestward prograding Michigan River (Mellen, 1947; Swann, 1964; Thomas, 1972c; Welch, 1972). The source terrain consists mainly of sedimentary rocks (Swann, 1964), which generally constitute a poor source of uranium.

A Ouachita source with sediments introduced laterally in central and north-central Mississippi along the platform edge that separated the Ouachita trough from the shallow platform (Thomas, 1972a) does not seem feasible. However, the Ouachitas constitute a sedimentary-metasedimentary provenance (Graham and others, 1976) and possibly a better source of uranium.

12 Pottsville Formation

Stratigraphic, sedimentological, and petrographic evidence point to the Alabama Piedmont and the Ouachitas as possible source areas for the detritus that composes the Pottsville Formation (Ferm and Ehrlich, 1967; Dennison and Wheeler, 1972; Graham and others, 1976). The Alabama Piedmont is considered to have been the more important source in terms of volume and realm of geographic spread of the detritus (Dennison and Wheeler, 1972). Graham and others (1976) propose that some sediment may have been contributed to the Pottsville from uplifts near the buried juncture or syntaxis between the Appalachian and Ouachita systems. A provenance in the southern Appalachians or Alabama Piedmont is supported by the fol- lowing evidence: (1) the directions of cross-bedding in the Pottsville (Metzger, 1965), (2) the southwestward thickening of the Pottsville across the basin, (3) the increase in quartz content coupled with a decrease in the lithic (greenschist) fraction of the Pottsville northeastward across the basin, and (4) the composition of Straven clasts as petrographically determined in this study (Table 2). The Alabama Piedmont is composed of sedimentary, metamorphic, plutonic(?) and Voioanic rocks, all of which have been metamorphosed, granitized, and migmatized; pegmatites; and minor mafic and ultramafic intrusive rocks (Deininger and others, 1964). Also, a number of localities with low-grade uranium mineralization have been reported from the Alabama Piedmont (Southern Interstate Nuclear Board, 1969).

RESULTS

RADIOMETRIC SURVEYS

Generally, the equivalent uranium content averaged higher in the shale, siltstone, and coal intervals (9 to 31 ppm eU) than in the sandstone and conglomerate intervals (0 to 14 ppm eU) [Table 1]. Along the basal contacts between the Hartselle Sandstone and Pride Mountain Forma- tion and between the Pottsville and Parkwood Formations, the average total counts per second ranged between those recorded for the underlying shales and the overlying sandstones.

PETROGRAPHY

The results obtained from petrographic analysis of Hartselle and Pottsville sandstones are reported in the "Major Rock Units under Con- sideration" section and are listed in Table 2. Petrographic analysis of clasts from the Straven Conglomerate Member outside the Coosa basin suggests a Valley and Ridge source for the sedimentary clasts and an Alabama Piedmont source for the metamorphic and volcanic clasts (Table 2).

CHEMISTRY

Samples of Hartselle Sandstone contained 1 to 2 ppm cU308; samples from the Pottsville Formation contained 1 to 3 ppm cU3 08 (Table 2).

13 Additional data on the cU3 08 content of samples from the Chattanooga Shale, Fort Payne Chert, Pride Mountain Formation, and Parkwood Formation are listed in Table 2. The results of the chemical U3 08 analyses tend to corroborate the results of the radiometric surveys.

The results of the trace element analyses indicate that the base of the Hartselle near and along the contact with the underlying shales of the Pride Mountain Formation is 4 to 5 times enriched in selenium and molybdenum (Table 2). Similarly, the basal Pottsville near the contact with the underlying shales of the Parkwood Formation appears to be enriched twofold in selenium and molybdenum. The contact zone between the Parkwood and Pottsville Formations appears to be enriched in selenium and molybdenum 2 times in comparison to the overlying Pottsville and the underlying Parkwood.

The chemical uranium concentration of the 70 stream-sediment samples from the Coosa basin analyzed by the Savannah River Laboratory ranges from 0.27 to 36.55 ppm U (Price and Ferguson, 1976). The median chemical uranium concentration of 2.16 ppm U is representative of the stream sediments in the Coosa basin. The higher value of 3.08 ppm U for the average chemical uranium concentration of the stream sediments in the basin is brought about by two anomalously high uranium concentrations reported from stream sediments associated with the Pottsville (15.04 ppm cU) in the Wattsville-Coal City subbasin and with the Floyd-Parkwood (36.55 ppm cU) in the Howard subbasin. These anomalously high uranium concentrations are questionable since subsequent fluorometric analyses of stream sediments collected from the original sample sites consistently showed less than 2 ppm U (Gilbert, 1976).

CONCLUSIONS

As indicated in "Favorability Characteristics," the Hartselle Sandstone and the Pottsville Formation possess a number of characteristics associated with sandstones which host uranium. In general, the diversity of the sandstones which host uranium indicates that mineralogy and depositional environments are not as important as combinations of other geologic factors in determining the favorability of sandstones as host rocks for uranium. Sandstone uranium deposits have been found in arkosic, feldspathic, quartzitic, and tuffaceous sandstones and conglomerates deposited in fluvial- deltaic, marginal-marine, barrier-bar, and lagoonal environments. Such deposits have been found in marginal-marine quartz arenites and feldspathic arenites, analogous to those of the Hartselle Sandstone, in the Texas Gulf Coastal Plain (Grutt, 1972). Most sandstone uranium deposits occur in fluvial-deltaic sandstones and conglomerates similar to those of the Pottsville.

Admixed volcanic detritus, such as that reported from upper Pottsville sandstones, provides a potential source of carbon dioxide which can generate carbonated ground waters with higher than normal uranium contents. Shale

14 intercalations provide important lithologic breaks in the flow of ground water; and when carbonaceous and pyritic, they may be effective in establishing and maintaining reducing conditions that promote the precipitation and retention of uranium. Shale and siltstone intercalations in an interval of sandstones generally provide suitable lithologic breaks in the flow of ground water and act to promote the emplacement of uranium along their contacts with the ad- joining sandstone. The limited areal extent of the Hartselle in the Coosa basin reduces the chances of finding such lithologic breaks or zones favorable for the emplacement of uranium. Pyrite, reported from shale and shaly sandstone intercalations in the Hartselle and from siltstones, coal beds, and underclays in the upper Pottsville sequence, was not observed in exposures of the Hart- selle and Pottsville during this study. Iron oxide staining of Hartselle and Pottsville exposures, often in the form of Liesegang banding, suggest the presence of pyrite in original unoxidized Hartselle and Pottsville rocks. Hartselle exposures locally exhibit abundant staining by manganese oxide and Pottsville sandstones are often bleached. However, due to the absence of uranium minerals, no relationship between alteration features and a redistri- bution of uranium minerals can be demonstrated. Coal in the Pottsville is indicative of a reducing depositional environment and early in its development constituted a potential precipitating agent of uranium. However, no sandstone uranium deposits are known to be associated with coal beds as thick as those of the Alabama Pottsville (Ferm and Ehrlich, 1971). The increased down- warp of the basin during the Early Pennsylvanian suggests that Pottsville sediments were deposited in continual reducing environments. Unconformities, such as those reported from the contact between the Parkwood and the Pottsville, are important because they enhance regional transmissivity to ground-water flow.

The steep dips of Hartselle and Pottsville exposures, generally exceeding 100, coupled with considerable surface leaching and oxidation, preclude any surface or shallow subsurface uranium mineralization. It is not known what effect the subsurface pinch-out of the Hartselle against the isopachous maximum of the basin may have had on the evolution of a uranium cell in the subsurface.

The source terrain of the Hartselle sediments is marginal as a potential source of uranium. The predominantly crystalline Alabama Piedmont, which sup- plied the bulk of Pottsville detritus, is a potentially viable source of uranium.

A number of studies have been published dealing with the distribution of arsenic, lead, selenium, molybdenum, and P2 05 relative to the ore zone of sandstone uranium deposits and with their use as indicator or pathfinder elements (Shoemaker and others, 1959; Gabelman, 1970; Grutt, 1972; Levinson, 1974). A review of these studies indicates that the increase in selenium and concentrations of molybdenum near and along the basal contact of the Hartselle and the Pottsville may satisfy some of the geochemical conditions commonly associated with sandstone uranium deposits.

Surface leaching and oxidation make it difficult to evaluate the results of the scintillometer surveys and chemical analyses for U3 08 with respect to the potential of Hartselle and Pottsville rocks as hosts foruranium. The low equivalent uranium values recorded in the surveys, coupled with the increased equivalent uranium values recorded for the fine-grained rocks, are not encouraging indicators with respect to the host-rock potential of the

15 coarser grained sandstones and conglomerates. Warm, humid climatic conditions are conducive to the leaching of uranium from potential source rocks; however, when these conditions are prolonged, as in the case of the southeastern United States since the Carboniferous, they lead to the removal of uranium from potential host rocks (Robertson, 1970). As a result, low-intensity anomalies could represent surface expressions of highly leached uranium ore (Finch, 1967). The lack of reduzate facies in outcrops of the Hartselle and Pottsville may be attributed to their exposure to prolonged periods of warm, humid climatic conditions after deposition, which resulted in the destruction of any reduzate facies through leaching and oxidation (Adler and Sharp, 1967).

Original, unoxidized Hartselle and Pottsville rocks may have possessed a higher potential as uranium host rocks than their present-day equivalents as indicated by:

1. The inferred presence of pyrite in original Hartselle and Pottsville rocks,

2. The abundance of carbonaceous organic matter in the original Pottsville.

3. The inferred feldspathic composition of some of the original Pottsville sandstones.

4. The inferred shallower dips of both formations prior to the Allegheny orogeny.

Dust rings, which separate the original clastic quartz grains from the secondary quartz overgrowths, indicate that some of the Hartselle and Potts- ville sandstones consisted of subrounded to well-rounded clasts, which made the original sandstones better transmitters of ground water. Cementation by secondary quartz overgrowths may have locked in and preserved an ancestral roll-front or a blanket-type deposit in the subsurface.

16 BIBLIOGRAPHY

Adler, H. H., 1970, Interpretation of colour relations in sandstone as a guide to uranium exploration and ore genesis, in Uranium exploration geology: Internat. Atomic Energy Agency, Panel Proc. Ser., Vienna, Austria, p. 331-342.

Adler, H. H., and Sharp, B. J., 1967, Uranium ore rolls - occurrence, genesis, and physical and chemical characteristics, in Uranium dis- tricts of southeastern Utah: Utah Geol. Soc. Guidebook 21, p. 53-77.

Butts, Charles, 1925, Coal fields of Alabama, in Analyses of Alabama coals: U.S. Bur. Mines Tech. Paper 347, p. 1-7.

1927, Description of the Bessemer and Vandiver quadrangles: U.S. Geol. Survey Atlas Folio 221, 22 p.

Carrington, T. J., 1965, Early Silurian - Early Mississippian interval, in Thomas, W. A., ed., Structural development of the southernmost Appalachians: Alabama Geol. Soc. 3rd Ann. Field Trip Guidebook, p. 19-22.

Carrington, T. J., Simpson, T. A., Joiner, T. J., and Hooks, W. G., 1965, Structure of the Birmingham region, in Thomas, W. A., ed., Structural development of the southernmost Appalachians: Alabama Geol. Soc. 3rd Ann. Field Trip Guidebook, p. 5-9.

Causey, L. V., 1963, Geology and ground-water resources of St. Clair County, Alabama - A reconnaissance: Alabama Geol. Survey Bull. 73, 74 p.

Clarke, 0. M., Jr., 1968, Clay and shale of northeastern Alabama: Alabama Geol. Survey Circ. 20-C, 99 p.

Cooper, B. N., 1964, Relation of stratigraphy to structure in the southern Appalachians, in Lowry, W. D., ed., Tectonics of the southern Appalachians: Virginia Polytech. Inst. Dept. Geol. Sci. Mem. 1, p. 108-110.

Culbertson, W. C., 1963, Correlation of the Parkwood Formation and the lower members of the Pottsville Formation in Alabama: U.S. Geol. Survey Prof. Paper 450E, p. 47-50.

1964, Geology and coal resources of the coal-bearing rocks of Alabama: U.S. Geol. Survey Bull. 1182-B, p. 45-51.

Deininger, R. W., Bentley, R. D., Carrington, T. J., Clarke, 0. M., Jr., Power, W. R., and Simpson, T. A., 1964, Alabama Piedmont geology: Alabama Geol. Survey 2nd Ann. Field Trip Guidebook, 64 p.

17 BIBLIOGRAPHY (continued)

Dennison, J. M., and Wheeler, W. H., 1972, Precambrian through Cretaceous strata of probable fluvial origin in southeastern United States and their potential as uranium host rocks: U.S. Atomic Energy Comm. GJO-4168-1, Open-File Rept., 211 p.

Drahovzal, J. A., and Neathery, T. L., 1971, Middle and Upper Ordovician stratigraphy of the Alabama Appalachians, in Drahovzal, J. A., and Neathery, T. L., eds., The Middle and Upper Ordovician of the Alabama Appalachians: Alabama Geol. Soc. 9th Ann. Field Trip Guidebook, p. 1-62.

Eardley, A. T., 1961, Structural geology of North America: New York, Harper, 624 p.

Ferm, J. C., and Ehrlich, Robert, 1967, Petrology and stratigraphy of the Alabama coal fields, in Ferm, J. C., Ehrlich, Robert, and Neathery, T. L., A field guide to Carboniferous detrital rocks in northern Alabama: Geol. Soc. America, Coal Div. 1967 Ann. Field Trip Guide- book, p. 11-15.

Ferm, J. C., and Galloway, N. C., 1971, Permo-Carboniferous depositional environments and radioactivity in eastern United States: U.S. Atomic Energy Comm. GJO-7405, Open-File Rept., 82 p.

Finch, W. I., 1967, Geology of epigenetic uranium deposits in sandstone in the United States: U.S. Geol. Survey Prof. Paper 538, 121 p.

1975, United States Geological Survey uranium and thorium resource assessment and exploration research program-Fiscal Year 1976: U.S. Geol. Survey Open-File Rept. 75-575, p. 19.

Gabelman, J. W., 1970, Metallotectonic control of uranium distribution, in Uranium exploration geology: Internat. Atomic Energy Agency, Panel Proc. Ser., Vienna, Austria, p. 187-203.

Gibson, A. M., 1895, Report upon the Coosa Coal Field: Alabama Geol. Survey Spec. Rept. 7, 143 p.

Gilbert, 0. E., Jr., 1976, Non-fossil fuel exploration in the Coosa synclinorium - Shelby, St. Clair, Jefferson and Calhoun Counties, Alabama: Alabama Geol. Survey, Open-File Rept., 79 p.

Graham, S. A., Ingersoll, R. V., and Dickinson, W. R., 1976, Common provenance for lithic grains in Carboniferous sandstones from Ouachita Mountains and Black Warrior Basin: Jour. Sed. Petrology, v. 46, p. 620-632.

18 BIBLIOGRAPHY (continued)

Grutt, E. W., Jr., 1972, Prospecting criteria for sandstone-type uranium, deposits, in Bowie, S.H.U., Davis, Michael, and Ostle, Dennis, eds., Uranium prospecting handbook: London, Inst...Mining and Metallurgy, p. 47-77.

Harshman, E. H., 1966, Genetic implications of some elements associated with uranium deposits, Shirley Basin, Wyoming: U.S. Geol. Survey Prof. Paper 550-C, p. 167-173.

1970, Uranium ore rolls in the United States, in Uranium exploration geology: Internat. Atomic Energy Agency, Panel Proc. Ser., Vienna, Austria, p. 219-232.

1972, Geology and uranium deposits, Shirley Basin area, Wyoming: U.S. Geol. Survey Prof. Paper 745, 82 p.

Johnston, W. D., Jr., 1930, Physical divisions of northern Alabama: Alabama Geol. Survey Bull. 38, 48 p.

1933, Ground water in the Paleozoic rocks of northern Alabama: Alabama Geol. Survey Spec. Rept. 16, pt. 1, 414 p.

Jones, W. B., 1925, Report on the Coal City Basin of the Coosa coal field in St. Clair County, Alabama: Alabama Geol. Survey, Open-File Rept., 60 p.

1929, Summary report on the Wattsville basin of the Coosa coal field: Alabama Geol. Survey Circ. 6, 48 p.

Levinson, A. A., 1974, Introduction to exploration geochemistry: Maywood, Illinois, Applied Publishing, 614 p.

McCalley, Henry, 1897, Report on the valley regions of Alabama (Paleozoic strata): Alabama Geol. Survey Spec. Rept. 9, pt. 2, 862 p.

Mellen, F. C., 1947, Black Warrior Basin, Alabama and Mississippi: Am. Assoc. Petroleum Geologists Bull. 31, pt. 2, p. 1801-1816.

Metzger, W. J., 1965, Pennsylvanian stratigraphy in the Warrior Basin, Alabama: Alabama Geol. Survey Circ. 30, 80 p.

Mueller, H. W., III, 1965, Deformational variation across strike in the southernmost Appalachians, in Thomas, W. A., ed., Structural development of the southernmost Appalachians: Alabama Geol. Soc. 3rd Ann. Field Trip Guidebook, p. 11-12.

Price, Van, and Ferguson, R. B., 1976, Savannah River Laboratory hydrogeochemical and stream sediment reconnaissance, Raw data release II, Orientation studies in Alabama: U.S. Energy Research and Devel. Adm. GJBX-46(76), Open-File rept., 8 p.

19 BIBLIOGRAPHY (continued)

Prouty, W. F., 1909, The Coosa coal field of Alabama: Eng. Mining Jour., p. 921-923.

1912, Map of the Coosa coal field with sections: Alabama Geol. Survey, scale 1:95,040.

Rich, R. A., Holland, D. H., and Peterson, Ulrich, 1975, Vein-type uranium deposits: U.S. Energy Research and Devel. Adm. GJO-1640, Open-File Rept., 383 p.

Robertson, D. S., 1970, Uranium: Its geological occurrence as a guide to exploration, in Uranium exploration geology: Internat. Atomic Energy Agency, Panel Proc. Ser., Vienna, Austria, p. 267-284.

Rothrock, H. H., 1948, Geology of the Coal City and Fairview basins, Coosa coal field, St. Clair County, Alabama - Preliminary Map Sheet 1: U.S. Geol. Survey in cooperation with Alabama Geol. Survey, scale 1:31,680.

1949a, Geology of area, in Investigation of coal deposits in the Fairview and Coal City basins, Coosa field, St. Clair County, Alabama - Reserves, petrology, and chemical properties of coals, washability characteristics of coal from Fairview bed; and geology of area: U.S. Bur. Mines Tech. Paper 719, pt. V, p. 32-50.

1949b, Geology and coal sources of the northeast part of the Coosa coal field, St. Clair County, Alabama: Alabama Geol. Survey Bull. 61, pt. 1, 163 p.

Savannah River Laboratory, 1976, Hydrogeochemical and stream sediment reconnaissance - eastern United States, Quarterly Report, January - March 1976: U.S. Energy Research and Devel. Adm. GJBX-17(76), Open- File Rept., 67 p.

Shoemaker, E. M., Miesch, A. T., Newman, W. L., and Riley, L. B., 1959, Elemental composition of sandstone-type deposits, in Garrels, R. M., and Larsen, E. S., III, compilers, Geology and mineralogy of the Colorado Plateau uranium ores: U.S. Geol. Survey Prof. Paper 320, p. 25-54.

Southern Interstate Nuclear Board, 1969, Uranium in the Southern United States: U.S. Atomic Energy Comm. WASH-1128, 230 p.

Stow, M. H., 1955, Report of radiometric reconnaissance in Virginia, North Carolina, eastern Tennessee, and parts of South Carolina, Georgia and Alabama: U.S. Atomic Energy Comm. RME-3107, 33 p.

Swann, D. H., 1964, Late Mississippian rhythmic sediments of Mississippi Valley: Am. Assoc. Petroleum Geologists Bull. 48, no. 5, p. 637-658.

20 BIBLIOGRAPHY (continued)

Thomas, W. A., 1965a, Ouachita influence on Mississippian lithofacies in Alabama, in Thomas, W. A., ed., Structural development of the southernmost Appalachians: Alabama Geol. Soc. 3rd Ann. Field Trip Guidebook, p. 23-28.

1965b, Upper Mississippian clastic facies, in Thomas, W. A., ed., Structural development of the southernmost Appalachians: Alabama Geol. Soc. 3rd Ann. Field Trip Guidebook, p. 56.

1967, Mississippian facies in Alabama, in Ferm, J. C., Ehrlich, Robert, and Neathery, T. L., A field guide to Carboniferous detrital rocks in northern Alabama: Geol. Soc. America, Coal Div. 1967 Ann. Field Trip Guidebook, p. 21-23.

1972a, Mississippian stratigraphy of Alabama: Alabama Geol. Survey Mon. 12, 121 p.

1972b, Regional stratigraphy in Mississippi between Ouachita and Appalachian Mountains: Am. Assoc. Petroleum Geologists Bull. 56, no. 1, p. 81-106.

1972c, Reply to S. W. Welch: Am. Assoc. Petroleum Geologists Bull. 56, no. 12, p. 2462-2463.

Thomas, W. A., and Mueller, H. W., III, 1965, Incompetent structures in Mississippian fine clastics, in Thomas, W. A., ed., Structural development of the southernmost Appalachians: Alabama Geol. Soc. 3rd Ann. Field Trip Guidebook, p. 48.

U.S. Atomic Energy Commission, 1966, Uranium exploration in the United States: Workshop Paper 3a, 7 p.

1970, Uranium ore guides in continental clastic sediments: Workshop Paper 4, 7 p.

U.S. Geological Survey, 1969, Birmingham quadrangle, Alabama: Natl. Topo. Map Series, scale 1:250,000.

Wanless, H. R., 1967, Regional setting of the Alabama coal basins, in Ferm, J. C., Ehrlich, Robert, and Neathery, T. L., A field guide to Carboniferous detrital rocks in northern Alabama: Geol. Soc. America, Coal Div. 1967 Ann. Field Trip Guidebook, p. 5-10.

Welch, S. W., 1972, Regional Paleozoic stratigraphy in Mississippi between Ouachita and Appalachian Mountains: Discussion: Am. Assoc. Petroleum Geologists Bull. 56, no. 12, p. 2461.

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