preliminary report of the uranium favorability of shear zones in the southern appalachians

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GJBX-128(78)
PRELIMINARY REPORT OF THE
URANIUM FAVORABILITY OF
SHEAR ZONES IN THE
CRYSTALLINE ROCKS OF THE
SOUTHERN APPALACHIANS
Bendix
Field Engineering Corporation
Grand Junction Operations
Grand Junction, Colorado 81501
Ir
November 1978
I 's
PREPARED FOR THE U.S. DEPARTMENT OF ENERGY
GRAND JUNCTION OFFICE
UNDER CONTRACT NO. EY-76-C-13-1664
metadc784605
I
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 responsibilityf or 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.
GJBX-128(78)
PRELIMINARY REPORT OF THE URANIUM FAVORABILITY OF SHEAR ZONES IN
THE CRYSTALLINE ROCKS OF THE SOUTHERN APPALACHIANS
H. M. Penley, E. H. Schot, and J. M. Sewell
BENDIX FIELD ENGINEERING CORPORATION
Grand Junction Operations
Grand Junction, Colorado 81501
November 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 and scope . . . . . . . . . . . . . . 2
Literature study and field investigations .2
North Harper Creek prospect . . . . . . . 2
Warwoman lineament . . . . . . . . . . .5
Towaliga fault anomaly . . . . . . . . .5
North Harper Creek prospect . . . . . . . . ... .5
Location . . . . . . . . . . . . ....... .5
Geology . . . . . . . . . . . . . . . . . . . 5
Nature and age of shearing . . . . . . . . . 11
Previous work and known uranium occurrences 11
Possible source of uranium . . . . . . . . . 11
Summary and conclusions . . . . . . . . . . 12
Warwoman lineament . . . . . . . . . . . . . . . .12
Location . . . . . . . . . . . . . . . . . . , 12
Geology - - - - - - - - - - - - - - - - - - 12
Blue Ridge province . . . . . . . . . . 13
Brevard cataclastic zone . . . . . . . 13
Piedmont province . . . . . . . . . . . 15
Nature and age of shearing . . . . . . . . . 16
Previous work and known uranium occurrences 16
Possible source of uranium . . . . . . . . . 17
Conclusions . . . . . . . . . . . . . . . . 17
iii
CONTENTS (continued)
Page
Towaliga fault anomaly ...... . 19
Location . . . 19
Geology.......... .. .. .. . . 19
Nature and age of shearing . . . 19
Previous work and known uranium occurrences . 19
Possible source of uranium . . . 20
Conclusions. .... .. . . . . . 20
Bibliography...................... . 21
iv
ILLUSTRATIONS
Page
Figure 1. Generalized geologic map of the southern
Appalachian region showing the three study areas 3
2. Location of sample sites in the
Grandfather Mountain window area,
North Carolina......... .... . . . . . . . .. .4
3. Generalized geology and cross section in the
Warwoman lineament area . . . . . . . . . . . . . . . 14
PLATES
Plate 1. Location of sample sites along the Warwoman lineament,
Georgia and South Carolina . . . . . . . . . . . . . . In pocket
2. Location of sample sites in the area of the Towaliga
fault anomaly, Lee County, Alabama . . . . . . . . . . . In pocket
TABLES
Table 1. Analyses of rock samples from the Grandfather
Mountain window, North Carolina . . . . . . . . . . 6
2. Analytical results from the Warwoman
lineament, Georgia and South Carolina . . . . . . . 8
3. Laboratory analyses of rock and soil samples from
the Towaliga fault anomaly, Lee County, Alabama . . . 10
V

SUMMARY
Three sheared areas in the crystalline Piedmont and Blue Ridge provinces,
from which uranium occurrences or anomalous radioactivity have been reported,
were studied to determine their favorability for uranium mineralization. The
study, which involved a literature review, geologic reconnaissance, ground
radiometric surveys, and sampling of rock outcrops for petrographic and chemical
analyses, indicates that more-detailed investigations of these and similar
areas are warranted.
In each area, surface leaching and deep residual cover make it difficult
to assess the potential for uranium mineralization on the basis of results from
chemical analyses for U 0 and the radiometric surveys. Although anomalous
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radioactivity and anomalous chemical uranium values were noted in only a few
rock exposures and samples from the shear zones, the potential for uranium
mineralization at depth could be much greater than indicated by these surface
data.
The study indicates that shear zones within Precambrian granitic basement
complexes (such as the Wilson Creek Gneiss of western North Carolina, the
Cranberry Gneiss of eastern Tennessee, and the Toxaway Gneiss of western South
Carolina) are favorable as hosts for uranium and may contain subsurface deposits.
Mylonitized graphitic schists immediately north of the Towaliga fault in Alabama
and Georgia may be favorable host rocks for uranium.
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INTRODUCTION
PURPOSE AND SCOPE
The potential for uranium deposits is probably greater in metamorphic
terrains, especially in those of Precambrian age, than in any other type of
nonsedimentary terrain in the eastern United States (Grauch and Zarinski,
1976). The Piedmont and Blue Ridge provinces are predominantly composed of
Precambrian sedimentary rocks that have been metamorphosed to mica schist and
biotite gneiss, and of intrusive granites that are Precambrian to upper Paleozoic
in age. Locally, the granites are mixed with older schist and gneiss to form
hybrid migmatites. Although the physical and chemical conditions leading to
the dispersion and concentration of uranium during metamorphism have yet to be
defined (Grauch and Zarinski, 1976), one of the probable effects of metamorphism
is the expulsion of potential mineralizing solutions from the metamorphosed
country rocks. Such solutions tend to follow paths of least resistance such
as fault, fracture, and shear zones.
Reconnaissance geologic investigations were conducted along three shear
zones in the Blue Ridge and Piedmont provinces of the southern Appalachians to
evaluate their potential as hosts for uranium. The three zones included
(1) the North Harper Creek prospect within the Grandfather Mountain window of
western North Carolina, (2) the Warwoman lineament of northeastern Georgia and
western South Carolina, and (3) an arcuate zone of anomalous radioactivity that
roughly parallels part of the Towaliga fault in east-central Alabama (Fig. 1).
Uranium occurrences or anomalous radioactivity have been reported from all
three shear zones. Each shear zone will be discussed individually because each
has a different geologic setting and history. The results of the study will
be used to provide recommendations for additional geologic investigations of
the study areas and to provide a basis for preliminary studies in areas with
similar structural and geologic settings.
The investigation was conducted by Bendix Field Engineering Corporation
(BFEC) for the Grand Junction Office of the U.S. Energy Research and Development
Administration (ERDA) as part of their National Uranium Resource Evaluation
program. ERDA subsequently became U.S. Department of Energy.
LITERATURE STUDY AND FIELD INVESTIGATIONS
Field work and review of available geologic information were conducted in
October and November 1976. Rock and saprolite samples were collected from the
shear zones, adjoining host rocks, and nearby potential source rocks. Scintil-
lometer readings were recorded at each sample location and in the immediate
areas of reported uranium occurrences.
North Harper Creek Prospect
Twenty rock and saprolite samples were collected from the North Harper
Creek prospect and other localities in the Wilson Creek Gneiss (Precambrian),
and from the overlying metasedimentary rocks of the Grandfather Mountain.window
(Fig. 2). These metasedimentary rocks range in age from late Precambrian to
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