Geology, Geochemistry, and 1\Y\ineral Resource Assessment of the Southern Nantahafa Wilderness and Adjacent Roadless Areas, Rabun and Towns Counties, Georgia, and ·· Clay and Macon Counties, North Carolina U.S. GEOLOGICAL SURVEY B Geology, Geochemistry, and Mineral Resource Assessment of the Southern Nantahala Wilderness and Adjacent Roadless Areas, Rabun and Towns Counties, Georgia, and Clay and Macon Counties, North Carolina By john D. Peper, Frank G. Lesure, Leslile j. Cox, and john P. D' Agostino U.S. GEOLOGICAL SURVEY BULLETIN 1883 U.S. DEPARTMENT OF THE INTERIOR MANUEL LUJAN, Jr., Secretary U.S. GEOLOGICAL SURVEY Dallas L. Peck, Director Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government UNITED STATES GOVERNMENT PRINTING OFFICE: 1991 For sale by the Books and Open-File Reports Section U.S. Geological Survey Federal Center, Box 25425 Denver, CO 80225 Library of Congress Cataloging in Publication Data Geology, geochemistry, and mineral resource assessment of the Southern Nantahala Wilderness and adjacent roadless areas, Rabun and Towns Counties, Georgia, and Clay and Macon Counties, North Carolina I by John D. Peper ... [et al.]. p. em. - (U.S. Geological Survey bulletin ; 1883) Bibliography; p. Supt. of Docs. no.: 119.3:1883 1. Geology-Southern Nantahala Wilderness (Ga. and N.C.). 2. Geology­ -Georgia-Southern Nantahala Roadless Area. 3. Geology­ Georgia-Buzzard Knob Roadless Area. 4. Mines and mineral resources­ Southern Nantahala Wilderness (Ga. and N.C.). 5. Mines and mineral resources-Georgia-Southern Nantahala Roadless Area. 6. Mines and mineral resources-Georgia-Buzzard Knob Roadless Area. 7. Southern Nantahala Wilderness (Ga. and N.C.). 8. Southern Nantahala Roadless Area (Ga.). 9. Buzzard Knob Roadless Area (Ga.). I. Peper, John D. II. Series. QE75.B9 no. 1883 [QE102.S6] 557.3 s-dc20 [557.58'123] 89-600065 STUDIES RELATED TO WILDERNESS The Wilderness Act (Public Law 88-577, September 3, 1964) and related acts require the U.S. Geological Survey and the U.S. Bureau of Mines to survey certain areas on Federal lands to determine the mineral values, if any, that may be present. Results must be made available to the public and be submitted to the President and Congress. This report presents the results of a geologic, geochemical, and mineral resource survey of the Southern Nantahala Wilderness, the Southern Nantahala Road­ less Area (U.S. Forest Service no. B8-025), and the Buzzard Knob Roadless Area (08-223). The Southern Nantahala Wilderness, partly in the Nantahala National For­ est, Clay and Macon Counties, N.C., and partly in the Chattahoochee National Forest, Rabun and Towns Counties, Ga., was established as a wilderness by the North Caro­ lina Wilderness Act of 1984 (Public Law 98-324, June 19, 1984) and the Georgia Wilderness Act of 1984 (Public Law 98-514, October 19, 1984) .. The Southern Nan­ tahala Roadless Area, Rabun County, Ga., and Buzzard Knob Roadless Area, Rabun and Towns Counties, Ga., are in the Chattahoochee National Forest just south of the wilderness. These two areas were classified as nonwilderness during the Second Road­ less Area Review and Evaluation (RARE II) by the U.S. Forest Service, January 1979. A multiple use classification for both areas was confirmed by the Georgia Wil­ derness Act of 1984 (Public Law 98-514, October 19, 1984). Ill CONTENTS Summary 1 Character and Setting 1 Mineral Resource Potential 3 Introduction 4 Location, Size, and Physiography 4 Previous Work 5 Present Work 6 Geology 6 Lithologic and Structural Setting 6 Regional Geologic Setting and Names of Rock Units 6 Hayesville and Hayesville(?) Faults 7 Richard Russell Thrust Sheet 7 Helen Thrust Sheet 7 Dahlonega Fault 8 Tallulah Falls Thrust Sheet 8 Regional Metamorphism 8 Regional Structural Fabric and Minor Fold Sequence 8 Major Folds and Cross-folds 10 Shope Fork Fault 12 River Mountain-Mill Creek Shear Zone 12 Chunky Gal Mountain Fault 13 Geochemistry 13 Sampling Procedures 13 Analytical Techniques 13 Discussion 14 Boron 14 Barium 14 Cobalt, Copper, Lead, and Zinc 14 Tin 14 Mineral Resource Assessment 14 Stone 14 Other Nonmetallic Commodities 15 Asbestos 15 Corundum 15 Feldspar and Sheet Mica 15 Olivine 15 Vermiculite 16 Potential for Oil and Gas 16 Potential for Gold and Other Metals 16 References 17 Contents V PLATES [Plates are in pocket] 1. Geologic map of the Southern Nantahala Wilderness and adjacent roadless areas 2. Geochemical maps of the Southern Nantahala Wilderness and adjacent roadless areas, Georgia and North Carolina FIGURES 1. Index map showing locations of wilderness and roadless areas in northeastern Georgia and adjacent North and South Carolina 2 2. Map showing major structural features in northeastern Georgia and adjacent North and South Carolina 3 3. Photograph showing view looking southeast across the Southern Nantahala Road­ less Area from the steep east slope of Scaly Knob toward Gulf Knob and Penson Knob 5 4. Photograph showing minor F2 fold exposed in roadcut 1 ,000 ft south of Boyd Chapel Cemetery and north of Hightower Creek, northeastern Macedonia quadrangle 9 5. Lower-hemisphere equal-area stereographic projection of F 1 and F2 fold axes mea­ sured in the Southern Nantahala Wilderness and adjacent roadless areas 10 6. Lower-hemisphere equal-area stereographic projection of F3 fold axes and mineral lineations measured in the Southern Nantahala Wilderness and adjacent roadless areas 10 7. Sketch map of the central part of the area of the geologic map showing the posi­ tion of the axial traces of major folds and cross-folds relative to the outcrop pat­ terns of major rock units 11 8. Sketch showing features in the River Mountain-Mill Creek shear zone 13 TABLES 1. Summary of types and number of geochemical samples and references to analytical data for the three study areas 22 2. Range and median concentrations of 24 elements in rock, soil, panned­ concentrate, and stream-sediment samples 23 3. Tin in geochemical samples 28 4. Some mines, prospects, and mineral occurrences in and near the Southern Nantahala Wilderness and adjacent roadless areas 29 VI Contents Geology, Geochemistry, and Mineral Resource Assessment of the Southern Nantahala Wilderness and Adjacent Roadless Areas, Rabun and Towns Counties, Georgia, and Clay and Macon Counties, North Carolina By john D. Peper, Frank G. Lesure, Leslie j. Cox, and john P. D'Agostino SUMMARY Character and Setting The Southern Nantahala Wilderness and the Buzzard The Southern Nantahala Wilderness and the adjacent Knob and Southern Nantahala Roadless Areas are near Buzzard Knob and Southern Nantahala Roadless Areas are one another and near the North Carolina-Georgia State in the Blue Ridge Mountains of northeastern Georgia and line in Rabun and Towns Counties, Ga., and Clay and Macon Counties, N.C. The areas collectively span a region southwestern North Carolina (fig. 1). The Southern Nan­ of polydeformed and metamorphosed rocks assigned to tahala Wilderness includes about 10,900 acres of the three major thrust sheets, from east to west the Tallulah Nantahala National Forest in Clay and Macon Counties, Falls, Helen, and Richard Russell thrust sheets. Outcrop N.C., and 12,439 acres of the Chattahoochee National patterns and minor structures in the older sillimanite­ Forest in Rabun and Towns Counties, Ga. The Southern grade Richard Russell rocks in the western part of the Nantahala Roadless Area includes about 5,100 acres of the study area outline an earlier phase of isoclinal folding not Chattahoochee National Forest in Rabun County, Ga., and apparent in the outcrop pattern of younger kyanite- and Buzzard Knob covers about 6,440 acres of the Chatta­ staurolite-grade Coweeta Group rocks immediately to the hoochee National Forest in Rabun and Towns Counties, Ga. east across the Shope Fork fault in the east-central parts of The areas are underlain by variably migmatized gneisses, the study area. Major movement on the Shope Fork fault schists, amphibolites, and calc-silicate granofels that are cut postdates isoclinal F1 folding but preceded F2 isoclinal by a few small to large lenses of leuco-granite, granodiorite, folding, because F1 fold traces are covered by rocks above and granitic pegmatite. Rocks in the central and western the fault and the fault is folded by F2 folds. Later shearing parts of the Southern N antahala Wilderness and in most of along the fault occurred during F3 cross-folding. Geologic the Buzzard Knob Roadless Area are assigned to the considerations and geochemical sampling and analysis Richard Russell Formation, whereas rocks east of the Shope suggest low potential for all mineral resources except Fork fault are mapped locally as the Coweeta Group of common building stone. The potential for some other Hatcher (1979b). These two groups might be partly equiv­ nonmetallic resources, including corundum, feldspar, alent to one another to the south or to the north of the area sheet mica, and vermiculite, is moderate to low. These are and both lie wholly within the Richard Russell thrust sheet. present in limited amounts but are currently of little economic value. The small deposits of soapstone present In the vicinity of the study area, however, there is broad in the areas are too impure to be considered a resource. evidence in the outcrop pattern of rock units indicating that Late Archaic-Early Woodland Indian bowl-carving sites in the Richard Russell rocks west of the Shope Fork fault are soapstone are an archeological heritage that might older and that they experienced an earlier phase of isoclinal deserve conservation. Oil and gas resource potential is folding than did the younger rocks of the Coweeta Group to unknown but believed to be small. Resource potential for the east. In addition, the Richard Russell rocks are locally gold is low; for massive sulfide deposits containing some metamorphosed to sillimanite-muscovite grade of metamor­ copper and zinc, it is low to moderate.