Stacked Crystalfne Thrust Sheets and 

Episodes of egiona Metamorphism in 

Northeastern Geo gi and Northwestern 

South Carorna-A einterpretation 
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Stacked Crystalline Thrust Sheets and 

Episodes of Regional Meta orphism in 

Northeastern Georgia and Northwestern 

South Carolina-A Reinter retation 

By ARTHUR E. NElSON 

Thrust sheets that underlie the Greenville quadrangle i 

northeastern Georgia and in northwestern South Carolin 

have been selectively metamorphosed and deformed du 

ing several Paleozoic prograde metamorphic events 

U.S. GEOlOGICAl SURVEY BUllETIN 1822 
DEPARTMENT OF THE INTERIOR 

DONALD PAUl HODEl, Secretary 

U.S. GEOLOGICAl SURVEY 

Dallas l. Peck, Director 

Any use of trade names and trade marks 

in this publication is for descriptive 

purposes only and does not constitute 

endorsement by the U.S. Geological Survey 

UNITED STATES GOVERNMENT PRINTING OFFICE 1988 

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 

Nelson, Arthur E. (Arthur Edward), 1922-

Stacked crystalline thrust sheets and episodes of regional metamorphism in 

northeastern Georgia and northwestern South Carolina. 

(U.S. Geological Survey bulletin ; 1822) 

Bibliography: p. 

Supt. of Docs. no.: I 19.3:1822 

1. Thrust faults (Geology)-Georgia. 2. Thrust faults (Geology)-South 

Carolina. 3. Metamorphism (Geology)-Georgia. 4. Metamoprhism 

(Geology)-South Carolina. I. Title. II. Series. 

QE75.B9 no. 1822 557.3 s [551.7'3'097572] 87-600409 

[QE606.5.U6] 
CONTENTS 

Abstract 1 

Introduction 1 

Previous work 1 

Acknowledgments 2 

General geology of the Blue Ridge 2 

Thrust sheets of the Blue Ridge-Described in ascending structural position 4 

Great Smoky thrust sheet 4 

Helen thrust sheet S 

Young Harris slice S 

Richard Russell thrust sheet S 

Tallulah Falls thrust sheet 6 

Thrust sheets of the Inner Piedmont-Described in ascending structural position 6 

Chauga-Walhalla thrust complex 6 

Six Mile thrust sheet 6 

Laurens thrust sheet 7 

Paris Mountain thrust sheet 7 

Thrust sheets of the Charlotte terrane 7 

Mafic-ultramafic thrust sheet 7 

Charlotte thrust sheet 7 

Deformation 7 

Metamorphism 9 

Discussion ll 

Conclusions l3 

References cited 14 

FIGURES 

1. Map showing previous interpretations of terranes of the southern Appalachian 

Mountains and location of the Greenville quadrangle 2 

2. Generalized tectonic map and cross section of the Greenville quadrangle 3 

3. Generalized schematic diagram showing the thrust sheet stacking order 

northwest of the Brevard zone 4 

4. Generalized tectonic map of the Greenville quadrangle showing metamorphic 

grade and metamorphic zones 10 

5. Generalized tectonic map of the Greenville quadrangle showing interpreted 

regional metamorphic ages for the various thrust sheets n 

TABLE 

1. Summary of fold phases observed in the northwestern part of the Greenville 

quadrangle, northwest of the Tallulah Falls thrust sheet 8 

Contents Ill 

Stacked Crystalline Thrust Sheets and Episodes of 

Regional Metamorphism in Northeastern Georgia and 

Northwestern South Carolina-A Reinterpretation 

By Arthur E. Nelson 

Abstract 

Parts of three major allochthonous terranes underlie 

the Greenville 1 ox 2° quadrangle, Georgia and South Carolina. From northwest to southeast, they are the eastern part 

of the Blue Ridge terrane, the Inner Piedmont, and the 

Charlotte terrane. The Brevard zone forms the tectonic 

boundary between the Blue Ridge terrane and the Inner 

Piedmont, and the Lowndesville shear zone forms the 

boundary between the Inner Piedmont and the Charlotte 

terrane. A total of eleven and possibly twelve westwardtransported crystalline thrust sheets compose these terranes in the Greenville quadrangle. The Blue Ridge terrane 

consists of a stack of five thrust sheets; the Inner Piedmont 

is underlain by four and possibly five thrust sheets, and 

two thrust sheets compose the Charlotte terrane. 

A variety of metasedimentary, igneous, and metaigneous rock assemblages compose the various thrust 

sheets. Some adjoining thrust sheets have metasedimentary units that are formed from sediments laid down in 

different depositional environments, and some thrust 

sheets contain distinctly different proportions and types of 

igneous and metaigneous rocks. 

Various Paleozoic prograde metamorphic or thermal 

events are recorded in the rocks of thrust sheets underlying the Greenville quadrangle. These events occurred at 

the following times: between 470 ·and 430 Ma, possibly 

between 430 and 410 Ma, about 365 Ma to possibly 344 

Ma, and 338 to 312 Ma. Generally the oldest metamorphic 

events are recorded in rocks of thrust sheets underlying 

the northwestern part of the quadrangle; successively 

younger metamorphic events are recorded in rocks of 

thrust sheets exposed to the southeast. These metamorphic events represent intense thermal-deformation pulses 

that are recorded in the rocks that were subjected to episodes of major westward thrusting. This thrusting 

emplaced a series of thrust sheets onto the North American Continent during the middle and late parts of the 

Paleozoic Era. 

INTRODUCTION 

Previously, workers showed that thrust sheets transported toward the west are the dominant structural feature in the Valley and Ridge province of the southern 

Appalachian orogen (fig. 1 ). Recent work has shown that 

the same structural style also dominates much of, the 

crystalline terrane east of the Valley and Ridge. Regional 

geologic investigations show that all the metamorphosed 

crystalline rocks underlying the Greenville 1 oX 2° quadrangle are allochthonous. Assemblages of these rocks 

form thrust sheets that were emplaced by tectonic transport toward the west. Recent seismic-reflection studies, 

the Consortium for Continental Reflection Profiling 

(COCORP) line (Cook and others, 1979), and the U.S. 

Geological Survey seismic lines (Harris and Bayer, 1979; 

Harris and others, 1981) present seismic profiles across 

different parts of the southern Appalachians. Each of 

these studies shows southeast-trending seismic profiles 

across several segments of the southern Appalachian 

Mountains. When taken together, these seismic profiles 

cross the major lithotectonic units that form the southern 

Appalachian Mountains from the Appalachian Plateaus 

in the northwest to the Coastal Plain in the southeast. 

These seismic studies clearly support the allochthonous 

nature of the crystalline rocks from the Blue Ridge to the 

Coastal Plain as suggested by geologic mapping. The 

studies also suggest that Paleozoic sedimentary rocks in 

several thrust sheets continue from the Valley aud Ridge 

beneath the crystalline rocks of the Blue Ridge and under 

a part of the western Inner Piedmont. Harris and Bayer 

(1979) suggest 179 km of westward transport for the 

crystalline rocks of the Blue Ridge. 

Previous Work 

Many geologic studies have been made within the 

Greenville quadrangle over a considerable time span. 

Introduction 1 
··-- .,.,.,.. -~"·,..~~, ......... , ..,., -~ .............. ·-·r-"""'"""~ ....... ~ -"""· 

J\L/\B ('\i\'!.\ ~ 

VALLEY 

AND 

RIDGE 

BLUE 

RIDGE 

INNER 

--f.I~_D~_Q~T_---­

PIEDMONT 

COASTAL 

PLAIN 

f 50 100 MILES 

50 100 KILOMETERS 

Figure 1. Previous interpretations of terranes of the southern Appalachian Mountains. The Greenville 1 ox 2° quadrangle is 

striped. Physiographic provinces discussed in the text are shown to the left. 

Yeates and McCallie (1896) and Park (1953) described 

some of the gold deposits and mining properties of 

Georgia. One of the major gold producing zones, the 

Dahlonega gold belt, extends northeast from Dahlonega 

and forms part of the Helen thrust sheet, defined on page 

5 in this report. Hopkins (1914) described soapstone, and 

Furcron and Teaque (1943) reported on mica-bearing 

pegmatites within the Greenville quadrangle. Crickmay 

(1952) and Hurst (1973) described rocks in this area as 

part of their general descriptions of Blue Ridge crystalline 

rocks. Hartley (1973) reported on the ultramafic rocks 

present in the northern part of the area, and Hatcher 

(1971) described the geology of Rabun and Habersham 

Counties, Ga. Hatcher also reported on various aspects of 

the tectonic history of northern Georgia (1974, 1976, 

1978a,b). Dupuis (1975) and Wooten (1980) mapped 

adjoining areas to the west and north, respectively, of the 

Greenville quadrangle, and Shellebarger (1980) and Gillon (1982) mapped areas in the northwestern part of the 

quadrangle. German (1985) mapped the Dahlonega gold 

belt, and Nelson (1982, 1983a,b, 1985) and Nelson and 

Koeppen (1986) mapped areas in the northwestern part 

of the Greenville quadrangle. In the Inner Piedmont and 

southeast of the Brevard zone, Griffin (1967, 1973, 197 4, 

1975, 1977, 1978, 1979, 1981) mapped a large part of the 

Greenville quadrangle in South Carolina. Grant (1958) 

mapped Hart County, Ga., and Hatcher (1969) mapped 

southeast of the Brevard zone. Nelson and others (1986) 

compiled a tectonic map of the Greenville quadrangle. 

Acknowledgments 

I thank Michael Higgins, J. Wright Horton, Jr., and 

James aarke for constructive criticism during field work, 

and I greatly appreciate the helpful reviews of the manuscript by Michael Higgins, Louis Pavlides, J. Wright 

Horton, Jr., and Thomas Neathery. 

GENERAL GEOLOGY OF THE BLUE RIDGE 

The distribution and the stacking order of the thrust 

sheets that form the allochthonous rocks underlying the 

Greenville quadrangle are shown in figure 2 (Nelson and 

others, 1986). Parts of three major allochthonous terranes underlie the Greenville quadrangle. From northwest 

2 Thrust Sheets and Regional Metamorphism, Georgia, South Carolina-A Reinterpretation 
0 20 MILES 1-----~---r-' 

0 30 KILOMETERS 

10 Autochthonous basement 

EXPLANATION 

Stacking order of thrust sheets 

BLUE RIDGE 

T Tallulah Falls thrust sheet 

R Richard Russell thrust sheet 

Y Young Harris slice 

H Helen thrust sheet 

G Great Smoky thrust sheet 

INNER PIEDMONT 

P Paris Mountain thrust sheet 

L Laurens thrust sheet 

S Six Mile thrust sheet 

C-W Chauga-Walhalla thrust complex 

CHARLOTTE TERRANE 

C Charlotte thrust sheet 

M Mafic-ultramafic thrust sheet 

----- Intrusive contact 

--r-..,...? Thrust fault-Teeth on upper plate; 

dashed where inferred; queried 

where questionable 

Granitic rock-shown only where 

extensive or where tectonic 

boundaries are obscured 

Figure 2. Generalized tectonic map and cross section of the Greenville 1°X2° quadrangle. 

to southeast, they are the eastern part of the Blue Ridge 

Mountains, the Inner Piedmont, and the Charlotte terrane. Each of the terranes consists of a series of westwardtransported stacked thrust sheets. The Brevard zone 

forms the tectonic boundary between the Blue Ridge and 

the Inner Piedmont, and the Lowndesville shear zone 

forms the boundary between the Inner Piedmont and the 

Charlotte terrane. A stack of five crystalline thrust sheets 

underlies the Blue Ridge terrane; a stack of four (possibly 

five) thrust sheets forms the Inner Piedmont. Two addiGeneral Geology of the Blue Ridge 3 · 
tional thrust sheets compose the Charlotte terrane in the 

Greenville quadrangle. In ascending order, the thrust 

sheets that form the Blue Ridge thrust stack are the Great 

Smoky thrust sheet, the Helen thrust sheet, the Young 

Harris slice, the Richard Russell thrust sheet, and the 

Tallulah Falls thrust sheet. The ascending stacking order 

for the Inner Piedmont thrust sheets are the ChaugaWalhalla thrust complex, the Six Mile thrust sheet, the 

Laurens thrust sheet, and the Paris Mountain thrust sheet. 

A mafic-ultramafic thrust sheet and the overlying Charlotte thrust sheet compose the Charlotte terrane. 

The metamorphosed stratified rocks of the Great 

Smoky thrust sheet include rock assemblages of the Late 

Proterozoic Ocoee Supergroup together with some minor 

Cambrian age rocks of the Murphy syncline. The ages of 

metasedimentary rock units in other thrust sheets, however, are uncertain, but the ages are thought to range from 

Late Proterozoic(?) to Ordovician(?). Two bodies of 

Middle Proterozoic (Grenville age, 1,200 Ma, Fullagar 

and others, 1979) basement rocks are present in the 

Tallulah Falls thrust sheet, but Middle Proterozoic basement has not been observed elsewhere in the Greenville 

quadrangle. In the adjoining Knoxville quadrangle to the 

north, Middle Proterozoic plutonic rocks and variably 

layered paragneisses are exposed in the eastern part of the 

Great Smoky thrust sheet (Hadley and Nelson, 1971; 

Nelson and Zietz, 1983). Where the basement rocks have 

been dated in the Blue Ridge province, the ages range 

from 1,000 to 1,300 Ma-ages typical of the Grenville 

province of eastern Canada and elsewhere in the Appalachian orogen (Rankin, 1975, p. 304). It is uncertain 

whether the Middle Proterozoic rocks represent detached 

fragments of the Grenvillian North American craton or 

possibly parts of an accreted terrane (Hatcher, 1978b; 

Zen, 1981; Nelson and Zeitz, 1983). 

The allochthonous rocks underlying the eastern 

Blue Ridge were previously divided into two major thrust 

sheets, the Hayesville sheet to the southeast and the Great 

Smoky sheet to the northwest (Hatcher, 1978b; Williams, 

1978; Nelson and Zietz, 1983). Nelson and Zietz (1983) 

divided the Hayesville thrust sheet into three major 

lithotectonic units, each of which has tectonic borders and 

contains distinctive rock assemblages juxtaposed along 

thrust faults. The two largest units were referred to as the 

east and west parts, and a third unit in the middle was 

called the Helen-Coweeta terrane. In this report, the east 

part of the Hayesville thrust sheet is named the Tallulah 

Falls thrust sheet; the west part is called the Richard 

Russell thrust sheet, and the terrane in the middle is 

called the Helen thrust sheet. 

Griffin (1970, 1971, 1974, 1977, 1978) divided the 

Inner Piedmont, extending from the Chauga belt 

(Hatcher, 1969) southeast of the Brevard zone to the 

Lowndesville shear zone, into a central core of sillimanite 

schist and gneiss that is flanked on either side by zones 

rich in amphibolite and granitoid gneiss. These zones are 

separated from each other by faults and tectonic slides. 

Griffin (1975) named the Walhalla, Six Mile, and Antreville nappes as parts of his core and flank complex and 

proposed a tectonic stockwork model for the Inner Piedmont. While many of the geologic interpretations are 

similar to those presented by Griffin, I have integrated the 

more recent COCORP seismic data and have interpreted 

the stacking order of the thrust sheets differently than was 

shown in the stockwork model. The Inner Piedmont has 

been divided into four and possibly five thrust sheets 

(Nelson and others, 1986). 

THRUST SHEETS OF THE BLUE RIDGEDESCRIBED IN ASCENDING STRUCTURAL 

POSITION 

Great Smoky Thrust Sheet 

The lowest crystalline thrust sheet in the Blue 

Ridge thrust stack is the Great Smoky thrust sheet (fig. 

3). Seismic reflection surveys (Harris and Bayer, 1979; 

Harris and others, 1981; Cook and others, 1979) support 

surface observations that the Great Smoky thrust sheet in 

the eastern Blue Ridge of Georgia was emplaced westward along the Great Smoky fault upon Paleozoic sedimentary rocks. These rocks may be an oceanward extension of the lower Paleozoic section in the Valley and. Ridge 

province to the northwest, in eastern Tennessee. The 

other westward-directed thrust sheets overlie the Great 

Smoky thrust sheet that is succeeded structurally to the 

southeast by the Richard Russell thrust sheet, the Young 

Harris slice, the Helen thrust sheet, and the Tallulah Falls 

thrust sheet (fig. 2). 

Middle Proterozoic (Grenville) basement rocks and 

rock assemblages of the Ocoee Supergroup, the 

Chilhowee Group, and the Murphy Group of Hatcher 

(1972), as used by Dallmeyer and others (1978), constiFigure 3. The thrust sheet stacking order northwest of the 

Brevard zone. Arrows show the direction of fault movement. 

4 Thrust Sheets and Regional Metamorphism, Georgia, South Carolina-A Reinterpretation 
tute the Great Smoky thrust sheet. Metamorphosed Late 

Proterozoic conglomerate, sandstone, quartzite, siltstone, 

and shale of the Ocoee Supergroup make up most of the 

Great Smoky thrust sheet in the Greenville quadrangle. 

Rocks of the Ocoee Supergroup in northeastern Georgia 

are interpreted as shallow water deposits in a fluviatile 

coastal-plain environment (Dupuis, 1975; Price, 1977; 

Shellebarger, 1980) that were probably deposited along 

the western side of a rift basin along the eastern margin of 

the North American craton. These rocks of the Ocoee do 

not contain volcanic deposits and are believed to have 

formed from sediments derived from the North American 

craton. 

The Great Smoky thrust fault defines the: base of 

the Great Smoky thrust sheet, but this fault is not exposed 

in the Greenville quadrangle. Farther west in Georgia and 

to the north in Tennessee, however, the Great Smoky 

thrust sheet rests on Paleozoic sedimentary rocks of the 

Valley and Ridge along the Great Smoky fault (Hadley 

and Goldsmith, 1963). The Hayesville thrust fault marks 

the upper boundary of the Great Smoky thrust sheet in 

the northwestern part of the Greenville quadrangle (figs. 

1 and 2). 

Helen Thrust Sheet 

Rocks of the Helen Group (Nelson and Gillon, 

1985) form the Helen thrust sheet that is exposed in the 

northwestern part of the Greenville quadrangle. This 

thrust sheet has a variable width and is overlain on the 

west by the Richard Russell thrust sheet and on the east 

by the Tallulah Falls thrust sheet. The Helen thrust sheet 

includes a variety of interlayered metagraywacke, including some very thinly laminated units that are distal 

turbidites, quartzite, graphite-bearing garnet-muscovitebiotite schist, metasiltstone, phyllite, feldspathic metasandstone (locally conglomeratic), thin muscovite-schist beds, 

some garnet-diopside-plagioclase-quartz granofels, and 

chemical metasediments (Stanton, 1976) represented by 

banded iron formation, manganiferous schists, and quartz 

magnitite rocks. Thin to thick layers of amphibolite are 

also present. Granitic and granodioritic gneisses interpreted to be intrusive rocks are included in the Helen 

thrust sheet, and numerous discontinuous pegmatite veins 

and pods of various sizes are also widely dispersed. The 

Helen Group, which constitutes most of the Helen thrust 

sheet, has been interpreted by Gillon (1982) to represent 

a rock sequence derived from sediment deposited in a 

moderate- to low-energy rift basin that has associated 

marine-pelitic and volcanic deposits. The volcanic rocks 

are believed to be the results of volcanism on the ocean 

floor. 

The Helen thrust sheet rests on the Great Smoky 

thrust sheet along the Allatoona fault, which is not 

exposed in the Greenville quadrangle but is exposed to the 

southwest. The Richard Russell thrust sheet rests on the 

Helen thrust sheet along the Hayesville thrust fault (fig. 

2), which, along with the Allatoona fault, forms the 

northwest border of the Helen thrust sheet. The Dahlonega fault, which forms the southeast border of the Helen 

thrust sheet, places the Tallulah Falls thrust sheet on top 

of the Helen thrust sheet (figs. 2 and 3). 

Young Harris Slice 

All thrust sheets overlying the Great Smoky thrust 

sheet contain a wide variety of ultramafic and mafic rocks 

that form small discontinuous pods, as well as some large 

mappable units (Hadley and Nelson, 1971; Nelson, 1982, 

1983a,b; Nelson and Zietz, 1983). These rocks are chiefly 

serpentinite, dunite, pyroxenite, eclogite, troctolite, 

gabbro, and amphibolite. Some of these rocks are rich 

locally in magnetite. A separate thrust slice of ultramafic 

and mafic rocks, named the Young Harris slice in this 

report, lies between the Great Smoky and the Richard 

Russell thrust sheets around the Brasstown Bald and 

Shooting Creek windows. At least parts of the Young 

Harris slice are a melange. The ultramafic rocks of the 

Young Harris slice have chemical affinities with mantle 

rocks (Hartley, 1973, p. 59), and additional geochemical 

studies suggest a midocean ridge or island-arc origin for 

them (Long and Miller, 1983). Shaw and Wasserburg 

{1984) analyzed a sample from the Young Harris slice 

and suggested that it represents oceanic crust. The Young 

Harris slice and other smaller mafic-ultramafic bodies 

may represent fragments of oceanic crust emplaced within 

the various thrust sheets during or before their westward 

transport. 

Richard Russell Thrust Sheet 

The Richard Russell Formation (Nelson and Gillon, 

1985) structurally overlies a previously unnamed rock 

assemblage, informally labeled in this report the schist of 

Crooked Creek. These two units form most of the Richard 

Russell thrust sheet, formerly the western part of the 

Hayesville thrust sheet. Intrusive rocks include granitic 

and dioritic gneisses along with variably layered granitic 

rocks; pegmatites, quartzofeldspathic segregations, and 

migmatitic biotite gneiss are locally abundant. The 

Richard Russell Formation consists primarily of thinly 

layered migmatitic garnet-biotite gneiss that is gradational 

to garnetiferous-feldspathic-argillaceous metasandstone 

interlayered with thin garnet-sillimanite-biotite schist. 

Smaller amounts of mica schist, quartzite, and small, 

discontinuous, thinly layered calc-silicate bands and minor 

amphibolite are present. The interlayered metasandstone 

and mica schist of the Richard Russell Formation resemThruat Sheeta of the Blue Rldge-Deacrlbed In Aacendlng Structural Position 5 
ble some of the metasandstone of the Ridgepole Mountain and Coleman River Formations of the Coweeta 

Group (Hatcher, 1979) and may correlate with them 

(R.D. Hatcher, oral commun., 1986). In a few places, 

some interlayered, thin psammitic and pelitic horizons 

with thicker and locally graded metasandstone& of the 

Richard Russell suggest that these rocks most likely 

formed as deep-water turbidite deposits (Gillon, 1982). 

The schist of Crooked Creek lies between the 

western part of the Richard Russell Formation and the 

Hayesville fault. This unit is composed of an irregularly 

layered sequence of reddish-weathering schist, finegrained quartz-feldspar gneiss, thinly to thickly layered 

amphibolite, hornblende gneiss, calc-silicate rocks, argillaceous to feldspathic metasandstone and (or) metagraywacke, and minor diamictite. The Crooked Creek 

contains a more heterogeneous rock assemblage and is 

generally more variably layered than the Richard Russell. 

The Crooked Creek has a higher metavolcanic and 

schist component and smaller amounts of feldspathic 

metasandstone and metagraywacke than does the Richard 

Russell Formation, which is characterized in this terrane 

by its low amphibolite content, by its high percentage of 

fine-grained, garnetiferous, biotite gneiss that is locally 

migmatitic, and by gneissic metasandstone that is 

interlayered with very thin pelitic horizons. To the northeast along strike, however, numerous amphibolite bodies 

are present in rocks that probably correlate with the 

Richard Russell. These lithologic differences between the 

Crooked Creek and the Richard Russell suggest that they 

may have formed in different environments, in different 

parts of a large depositional basin, or in a basin that had 

a large influx of volcanic material during deposition of the 

Crooked Creek. In the northern part of the quadrangle, a 

fault separates the Richard Russell from the Crooked 

Creek, but elsewhere the nature of the contact between 

the two rock units is obscure, and it is difficult to 

determine if it is tectonic or depositional. Within the 

Crooked Creek and the Richard Russell, bedding is rarely 

preserved; instead, a discontinuous compositional layering is the most prevalent structure. This results from 

metamorphic differentiation and transposition of bedding 

into the regional foliation (Nelson, 1983a,b ). 

Geologic field evidence at hand does not support 

the subdivision of the Richard Russell thrust sheet. The 

Crooked Creek underlying the western part of the Richard 

Russell thrust sheet is lithologically similar to and might 

correlate with the rocks of the Zebulon thrust sheet 

(Higgins and others, 1984). 

Tallulah Falls Thrust Sheet 

Several metamorphosed sedimentary rock assemblages, a variety of intrusive rocks, pegmatites, and some 

Grenville basement plutonic rocks (Fullagar and others, 

1979), make up the Tallulah Falls thrust sheet. The 

Tallulah Falls sheet overlies the Helen thrust sheet along 

the Dahlonega fault. To the southeast, the Tallulah Falls 

thrust sheet is bounded by the Brevard zone. The Tallulah 

Falls Formation of Galpin (1915), as used by Hatcher 

(1971), forms a large part of the thrust sheet and consists 

of the following members: (1) a lower metagraywackeschist-amphibolite, (2) an aluminous schist, (3) a 

metagraywacke-schist, and ( 4) an upper quartzite-schist 

(Hatcher, 1976). The Union Grove sequence (Gillon, 

1982) of metagraywacke, biotite schist and gneiss, amphibolite, calc-silicate granofels, and some epidote quartzite 

is present along the southeast side of the Dahlonega fault. 

These rocks correlate with the lower metagraywackeschist-amphibolite member of the Tallulah Falls Formation. Gillon (1982) considered the metasedimentary rock 

assemblages of the Union Grove sequence to represent 

sediments deposited in a fluvial-delta to distalturbidite environment. Intrusive rocks include granitic, 

granodioritic, quartz monzonitic, and tonalitic gneisses 

and pegmatite. 

THRUST SHEETS OF THE INNER 

PIEDMONT -DESCRIBED IN ASCENDING 

STRUCTURAL POSITION 

Chauga-Walhalla Thrust Complex 

The Chauga River and the Poor Mountain Formations of Hatcher (1969), together with rocks of the 

Walhalla nappe (Griffin, 1974 ), form the 

Chauga-Walhalla thrust complex. This thrust complex 

includes button phyllonites, graphite phyllonite, carbonate 

rocks, considerable amphibolite, granitoid, hornblende 

gneiss, quartzite, feldspathic quartzite, various types of 

biotite gneiss, migmatite, and mica gneisses. These rocks 

probably originated from sediments derived from a deeply 

weathered source and deposited both on a shelf and in an 

associated rift basin that also received considerable oceanfloor volcanic deposits. 

Griffin (1974) interpreted the contact between the 

rocks of the Chauga belt and his Walhalla nappe to be a 

tectonic slide; elsewhere, Hatcher and Acker (1984) 

interpreted this contact as a metamorphic gradient. Our 

work suggests that there is a structural discontinuity 

locally between these lithotectonic units but that in other 

places the contact appears to be a metamorphic gradient. 

The Chauga-Walhalla thrust complex overlies the Tallulah 

Falls thrust sheet along the Brevard zone. 

Six Mile Thrust Sheet 

In this thrust sheet, the mapped units are unnamed 

and consist of varying assemblages of many rock types. In 

8 Thrust Sheets and Regional Metamorphism, Georgia, South Carolina-A Reinterpretation 
order of decreasing abundance, they are mica :;chist, 

red-weathering biotite schist, sillimanite schist and gneiss, 

amphibolite, various biotite gneisses (some of whieh are 

porphyroblastic ), felsic gneiss, metagraywacke, some manganiferous schist, and gondite. The layering varies from 

thin to thick, and some is massive; the rocks are commonly deeply weathered. These rocks probably formed 

from sediments deposited in an environment that also 

received considerable volcanic materials. 

The Six Mile thrust sheet is believed to rest on the 

Chauga-Walhalla thrust complex along a tectonic slide 

(Griffin, 1973). This tectonic slide is difficult to trace in 

the field, but lithologic and structural discontinuities along 

the contact and the higher metamorphic grade of the 

rocks forming the Six Mile sheet contrast with the lower 

grade rocks of the adjoining Chauga-Walhalla thrust 

complex. A low-angle thrust fault separating these sheets 

has been seen but is difficult to map. Numerous variably 

sized klippen of the Six Mile thrust sheet are present in 

the Chauga-Walhalla thrust complex. 

Laurens Thrust Sheet 

The principal rock type of the Laurens thrust sheet 

is a layered biotite gneiss. Individual layers art: very 

noticeable in large outcrops. Amphibolite, hornblende 

gneiss, some biotite schist, and locally, considerable 

granitoid are also present. These rocks appear to be 

mostly meta\Ulcanic rocks that were probably deposited 

in an island-arc environment. The Laurens thrust sheet 

overlies the Six Mile thrust sheet along an unnamed fault. 

Paris Mountain Thrust Sheet 

Sillimanite schist is the predominant rock type in 

the Paris Mountain thrust sheet. Amphibolite is p:resent 

locally near the western margin; elsewhere, metasiltstone, 

quartzite, garnet-sillimanite schist, sillimanite-bearing 

felsic gneiss, and a marker bed of garnet -quartz granulite 

are present. Granite plutons are present throughout the 

terrane, composing about half of the thrust sheet's volume. The Paris Mountain thrust sheet overlies both the 

Six Mile and Laurens thrust sheets along an unnamed 

fault. 

THRUST SHEETS OF THE CHARLOTTE 

TERRANE 

Mafic-Ultramafic Thrust Sheet 

An assemblage of ultramafic, mafic, and fragmental 

mafic rocks, together with some variably sized granitic 

bodies, composes a terrane on the southeast side of the 

Lowndesville shear zone near the southern border of the 

Greenville quadrangle. To the northeast, this terrane is 

overlain by the Charlotte thrust sheet. The boundary 

between the t\\0 terranes has not been observed but is 

inferred to be a thrust fault. 

The mafic-ultramafic terrane is deeply weathered 

to a saprolite, and the distribution of fresh rock exposures 

is sparse. Some of the saprolite is derived from a fragmental rock that had a hornblende-rich matrix. The fragments 

in the saprolite were originally gabbro, ultramafic rock, 

and some siliceous rock. Because of the deep weathering, 

the distribution of much of the rock types within the 

terrane is uncertain. However, since this terrane is along 

strike with the Macon melange (Higgins and Crawford, 

1985) to the southwest, it is probably also a melange. Like 

the Young Harris slice, these rocks are probably derived 

from ocean crust or a midocean ridge. 

Charlotte Thrust Sheet 

Formations and unnamed rock units that compose 

the Kings Mountain belt, Charlotte belt, and Carolina 

slate belt make up the Charlotte thrust sheet. These rocks 

include phyllite, greenstone, metamorphosed intermediate volcanic tuffs and lava flows, amphibolite, metasandstone, metagraywacke, metasiltstone, various biotite gneiss 

and mica schist units, and intrusive rocks. Granite, 

granodiorite, pyroxenite, and variably interlayered and 

textured gabbro form the principal intrusive rocks. The 

Charlotte thrust sheet and the mafic-ultramafic terrane 

overlie rocks of the Six Mile and Laurens thrust sheets 

along the Lowndesville shear zone. 

DEFORMATION 

All the thrust sheets and some rocks within fault 

zones have experienced several episodes of deformation. 

Detailed studies in the northwestern part of the Greenville 2° quadrangle have shown that the rocks have been 

deformed by folding at least four and possibly six times 

(Nelson, 1985). Small interference folds are commonly 

seen at rock exposures, and the present outcrop patterns 

of large structural features, such as the the large Chattahoochee basin (Nelson, 1985) and the Tallulah Falls 

dome (Hatcher, 1971), have resulted from superposed 

folding (Dallmeyer and others, 1978; Hatcher, 1974; 

Nelson, 1985). The first generation folds are represented 

by intrafolial, rootless, and recumbent isoclinal folds in 

transposed layers. Second generation folds (F 2 ), which 

form the major folds, are steeply inclined to recumbent. 

The limbs of F2 folds have been folded into two sets of 

tight to open, upright to overturned flexure folds. These 

later folds form conjugate fold pairs. All the above 

Deformation 7 
mentioned folds have axial planar cleavages. A later 

folding event gently folded the flanks of some late flexure 

folds, but axial plane cleavage has not been identified with 

these later folds. 

Most of the major folds (F2 ) trend northeast, and 

their axes plunge gently northeast or southwest. These 

folds range from upright to inclined to recumbent, and 

although some of them verge southeast, most verge 

northwest. Regional F 2 folds in the Great Smoky thrust 

sheet are mostly overturned to the northwest, and their 

axial surfaces are steeply inclined. In the Richard Russell 

sheet, most of the F2 folds are reclined to recumbent and, 

depending on their location with reference to the Chattahoochee basin, have variable orientations reflecting 

considerable F3 (northwesterly and northeasterly) strain. 

In contrast, in both the Helen thrust sheet and the Tallulah 

thrust sheet west of the Tallulah Falls dome, the F 2 folds 

generally have steeply dipping axial surfaces overturned 

to the southeast, and their axes generally plunge northeast 

or southwest. These fold attitudes are believed to result 

from later superposed folding associated with development of basins and domes in this part of the Greenville 

quadrangle (Nelson, 1985). Table 1 summarizes the types 

of folds characteristic of each fold phase. 

In many places, the rocks display multiple sets of 

planar surfaces-foliation, cleavage, metamorphic layering, and bedding (table 1). The first foliation (S1) is 

considered to have formed during a regional metamorphic event and was later deformed during regional folding 

(F2 ) that probably occurred after the high temperature 

peak of metamorphism (Nelson, 1985). Moderate temperatures may have continued through a third episode of 

folding (F3 ). This is indicated by biotite that has grown 

Table I. Summary of fold phases observed in the northwestern part of the Greenville quadrangle, northwest of the 

Tallulah Falls thrust sheet 

Fold 

phases Characteristics of phases 

F 1 . . . . • • . • Rootless recumbent to reclined isoclinal folds 

that trend northeasterly; may be coplanar with 

F2 folds and lie in the transposed S1 foliation. 

F2 •.•••••• Steep to recumbent isoclinal folds; form major 

folds and fold sl foliation; probably are postpeak metamorphism; rarely have well-developed axial-plane ~ foliations. 

F8 •••••.•• Upright to slightly inclined conjugate fold pairs 

that have axial-planar crenulation cleavage in 

pelitic units; probably late metamorphic; conjugate fold sets trend northeasterly and northwesterly. 

F 4 • • • • • • • • Poorly developed, gentle, upright folds and warps 

that have east-northeast- and north-northeasttrending axes; axial-plane cleavage has not 

been observed with these later folds. 

along the axial-plane cleavage of third-generation folds. 

This later folding event may also represent a separate 

thermal pulse. 

Regional relations suggest that the Richard Russell 

thrust sheet was emplaced in a westward direction over the 

Great Smoky thrust sheet along the Hayesville fault. This 

fault is probably pre- to synmetamorphic but formed 

before the regional metamorphic peak (Shellebarger, 

1980; Wooten, 1980). North of the Greenville quadrangle, 

Wooten reported that the fault is folded by F2 folds; it does 

not appear to offset the sillimanite isograd or to juxtapose 

rocks of different metamorphic grade. In the Greenville 

quadrangle or in an area to the north, the first generation 

foliation attitudes in rocks on either side of the fault do 

not appear to be deflected (Wooten, 1980). At a few 

places along the fault, however, some rocks of the Richard 

Russell thrust sheet have small zones where blastomylonite and mylonite textures are preserved (Shellebarger, 

1980). 

The northwestern side of the Helen thrust sheet is 

bounded by an unnamed fault. Foliation attitudes appear 

to be parallel in rocks on both sides of the fault; however, 

local discordances of foliation attitudes between the Helen 

and the Richard Russell thrust sheets suggest some 

post-S1 foliation movement along at least part of the fault. 

From the Georgia-North Carolina boundary, the unnamed 

fault extends southwestward toward Dahlonega (Gillon, 

1982), where it appears to join the Hayesville fault west of 

the Greenville quadrangle. If the Hayesville and the 

unnamed fault are the same, as the present interpretation 

suggests, then the Hayesville fault does not continue 

southwestward through Georgia as depicted by Williams 

(1978). Southwest of the Greenville quadrangle, McConnell and Costello (1980) correlated the Allatoona fault 

with the Hayesville fault, but Higgins and others (1984; 

1988) mapped the Allatoona fault as the northwesternmost boundary of the Ropes Creek thrust sheet. 

The Dahlonega fault (Crickmay, 1952) juxtaposes 

the southeastern part of the Helen thrust sheet, whose 

rocks are nonmigmatitic, with highly migmatitic rocks of 

the Tallulah Falls thrust sheet. Early ductile deformation 

along the fault formed mylonites and blastomylonites, but 

later brittle deformation formed button schists and 

intensely fractured the rocks (Bowen, 1961; McConnell 

and Costello, 1980; Gillon, 1982). Ductile deformation 

along the Dahlonega fault probably began near the 

metamorphic peak, and later brittle deformation probably occurred after temperatures had cooled to near the 

lower temperature boundary of greenschist facies conditions (Sibson, 1977). 

Although a detailed structural study has not been 

completed southeast of the Brevard zone, preliminary 

work shows that these rocks were also polydeformed. 

Similar styles of superposed folds are present and the 

major folds also trend northeast. Rock exposures also 

8 Thrust Sheets and Regional Metamorphism, Georgia, South Carolina-A Reinterpretation 
display planar structures such as metamorphic layering, 

foliation, schistosity, and cleavage. In places, several of 

these planar fabrics are displayed in the same exposure. 

Rocks in both the Brevard zone and the Lowndesville shear zone are also polydeformed. Early ductille and 

later brittle deformation fabrics are common (r\"elson, 

1981 ), and several generations of folding are evide:nt, as 

are several generations of cleavage. 

The Lowndesville shear zone closely follows a major 

gravity gradient that trends northeast across the eastern 

United States (American Geophysical Union, 1964; 

Bouguer gravity map compiled from data on file at the 

Defense Mapping Agency). The significance of this gravity gradient and its relations to the Lowndesville shear 

zone are unknown. The gravity gradient probably rdlects 

a major change in the deeply buried basement. Griffin 

(1970) suggested that northwestward thrusting and development of the mobile Inner Piedmont core was related to 

underthrusting of the continental crust by an a<:eanic 

plate. The gravity gradient may reflect the juxtaposition of 

continental basement to the northwest and oceanic crust 

to the southeast (Hatcher and Zeitz, 1980; Nelson, 1981). 

METAMORPHISM 

Metamorphic gradients exist within some thrust 

sheets, and some thrust faults juxtapose terranes of 

differing metamorphic grade (figs. 4 and 5). Northwest of 

the Brevard zone in the Blue Ridge, the Great Smoky 

thrust sheet has regional metamorphic zones ranging 

from chlorite (in the northwest) to sillimanite (in the 

southeast) (Hadley and Nelson, 1971). In the Greenville 

quadrangle, however, the rocks of the Great Smoky sheet 

range from garnet to sillimanite-muscovite zones (Shellebarger, 1980; Gillon, 1982). In the overlying Richard 

Russell thrust sheet, the rocks appear to be mostly in the 

sillimanite-muscovite zone (Gillon, 1982; Nelson and 

Zietz, 1983), although to the northeast, beyond the quadrangle boundary, some of the rocks are in the granulite 

facies of regional metamorphism (Eckert and 1~ohr, 

1985). The Helen thrust sheet is exposed in a relatively 

narrow zone and generally contains lower grade rocks 

than does the adjoining Richard Russell thrust sht~et to 

the northwest or the Tallulah Falls thrust sheet to the 

southeast. Rocks in the Helen thrust sheet range from the 

garnet to staurolite and kyanite zones (Gillon, 1982; 

Nelson, 1982, 1983a). To the southeast, the Tallulah Falls 

thrust sheet includes rocks ranging from the kyanite to 

sillimanite-muscovite zones (Hatcher, 197 6; Roper and 

Dunn, 1970). 

Southeast of the Brevard zone, the Chauga-Walhalla 

thrust complex of the Inner Piedmont contains prograde 

metamorphic rocks ranging from the greenschist facies to 

the kyanite zone of the amphibolite facies. Most of the 

rocks in the Chauga part of the complex are in the 

greenschist facies. To the southeast, the metamorphic 

grade gradually increases to kyanite in the Walhalla part 

of the thrust complex (Griffin, 1967, 1975; Hatcher, 

1969). To the southeast, the Six Mile thrust sheet is 

mostly in the sillimanite-muscovite zone, but locally it is 

in the kyanite zone (Griffin, 1975). The Paris Mountain 

and Laurens thrust sheets farther to the east are in the 

sillimanite-muscovite zone. 

Southeast of the Lowndesville shear zone, highly 

weathered and altered mafic and ultramafic rocks of the 

mafic-ultramafic terrane are poorly exposed, and, 

although metamorphic data are sparse, the rocks appear 

to be at medium grade. Adjoining the mafic-ultramafic 

terrane to the northeast is the Charlotte thrust sheet that 

includes rocks of the Carolina slate belt that are in the 

biotite-chlorite zone of the greenschist facies. Also 

included are rocks of the Kings Mountain belt and the 

Charlotte belt that are in the amphibolite facies. 

Retrograded metamorphic rocks are exposed in and 

near the Brevard zone and the Lowndesville shear zone. 

In addition, retrograded metamorphic rocks are also 

associated with some smaller shear zones elsewhere in the 

quadrangle. 

Much radiometric whole rock and mineral age 

dating has been done on samples from the southern 

Appalachian Mountains (Long and others, 1959; Kulp 

and Eckelmann, 1961; Butler, 1972; Odom and Fullagar, 

1973; Dallmeyer, 1975, 1978; Fullagar and Butler, 1979; 

Harper and Fullagar, 1981; Fullager and Kish, 1981; 

Whitney and others, 1976; Odom and others, 1976; 

Medlin, 1968). This radiometric dating includes the U-Pb 

zircon, K-Ar, 40 Ar-39 Ar, and Rb-Sr methods. The oldest 

period of regional metamorphism recorded in the southern Appalachian Mountains occurred about 1,000-1,200 

Ma (Hadley and Goldsmith, 1963; Rankin and others, 

1969), but there was also a thermal peak about 800--900 

Ma. In the Blue Ridge thrust sheet, mostly Great Smoky 

thrust sheet of this report, Butler (1972) indicates that a 

Paleozoic Barrovian-type prograde metamorphism 

occurred between 430 and 470 Ma, probably during the 

Taconic orogeny; a possible period of metamorphism also 

occurred about 380 Ma (Acadian) when the Spruce Pine 

pegmatites originated. In addition, he indicated an episode of retrograde metamorphism that was particularly 

intense along the Brevard zone and along other faults but 

which was sporadically developed elsewhere. This retrograde metamorphism appears to be associated with late 

Paleozoic deformation and thrust faulting but could also 

be the result of uplift and cooling and not necessarily a 

separate thermal event (Shellebarger, 1980). Dallmeyer 

(1975) also concluded that the Blue Ridge was regionally 

metamorphosed about 480 Ma. Butler (1972) considered 

the Inner Piedmont to have been metamorphosed about 

Metamorphism 9 
840 

N 

L-M t 

0 20 MILES 1-----,.L-------,-l 

0 30 KILOMETERS 

EXPLANATION 

METAMORPHIC GRADE 

~ Low to medium grade 

~ Medium grade 

METAMORPHIC ZONES 

[D Sillimanite 

0 Kyanite 

0 Staurolite 

~ Garnet 

I •· •. R' .• I Retrograded 

Granitic rocks shown where 

they obscure faults or where 

extensive 

-...._~'1. Thrust fault-Teeth on 

upper plate; dashed 

where inferred; queried 

where questionable 

-....§ _..- lsograd-dashed where inferred 

K 

~ Intrusive contact 

Figure 4. Generalized tectonic map of the Greenville 1°X2° quadrangle showing metamorphic grade and metamorphic 

zones. 

410-430 Ma and that belts to the southeast were metamorphosed about 380--420 Ma. 

Odom and others (1976) indicated that a part of the 

southern Appalachians in Alabama and Georgia that 

corresponds to the Tallulah Falls thrust sheet was regionally metamorphosed about 370 Ma. Dallmeyer (1978) 

gave evidence to support a regional metamorphic event in 

the Inner Piedmont of Georgia at about 365 Ma. 

Shearing and recrystallization and tectonism in the 

Brevard zone have been dated around 356 Ma (Odom 

and Fullagar, 1973). The minimum age for mylonite 

formation in the Lowndesville shear zone is reported as 

10 Thrust Sheets and Regional Metamorphism, Georgia, South Carolina-A Reinterpretation 
0 20 MILES ~----.-L------rl 

0 KILOMETERS 

EXPLANATION 

Letter symbols correspond to those of figure 2 

~ 43Q-470 Ma a 312-338 Ma 

[]JI] -365 Ma Granitic rocks 

EJJ -365 Ma ~ Contact . or possibly 

41Q-430 rna -.._.'\. Thrust fault-Teeth on 

~ upper plate; dashed 

-344 Ma where inferred; queried 

where questionable 

Figure 5. Generalized tectonic map of the Greenville 1°X2° quadrangle showing interpreted regional metamorphic 

ages for various thrust sheets. 

350 Ma (Davis, 1980; Horton, 1981), but in the study 

area, recent unpublished radiometric zircon age data (T. 

Stern, written commun., 1986) suggest that the mylonites 

of the Lowndesville shear zone were formed between 312 

and 344 Ma. The Brevard zone and the Lowndesville 

shear zone form the tectonic boundaries for three of the 

major allochthonous terranes in the study area, and they 

must have been subject to major tectonism approximately 

312-356 Ma. 

DISCUSSION 

Rocks in all thrust sheets are polymetamorphic and 

polydeformed. Some rocks contain two postregional 

metamorphic schistosity or cleavage surfaces, and some 

rocks have been folded at least four times (Nelson, 1985). 

Small patches of retrograded rocks are irregularly dispersed in all thrust sheets, but the most intensely retrograded rocks are in or close to the Brevard zone or the 

Discussion 11 
Lowndesville shear zone. Locally, a diamictite contains 

some medium -grade metamorphic boulders and rock 

fragments whose foliation-schistosity trends are discordant to the regional schistosity of the enclosing matrix. 

This suggests that the boulders and their source rock unit 

within the same thrust sheet had a previous prograde 

metamorphic history. Other evidence to support preregional metamorphic events, however, is rare, and most 

probably, if there were early prograde events, much of the 

evidence was destroyed as each thrust sheet was regionally 

metamorphosed under relatively high grade conditions. 

Even though considerable isotopic dating has been 

done in the southern Appalachians, the orogenic evolution 

and age of metamorphism of some allochthonous terranes in the orogen remain enigmatic. The Greenville 

quadrangle is underlain by a series of stacked thrust 

sheets extending from the Blue Ridge province through 

the Inner Piedmont and into the Piedmont province. 

Some of these thrust sheets correlate with terranes where 

the regional metamorphism has been dated. For example, 

the Great Smoky thrust sheet, the Richard Russell thrust 

sheet, and the Helen thrust sheet form a large part of the 

terrane that was metamorphosed 430-470 Ma (Butler, 

1972). Rocks within the Tallulah Falls thrust sheet, however, appear to have conflicting isotopic dates. Rock units 

of the Tallulah Falls thrust sheet were previous] y thought 

to correlate with rocks to the northeast that were regionally metamorphosed between 430 and 470 Ma (Butler, 

1972); however, these rocks to the northeast are now 

believed to be from the Great Smoky and the Richard 

Russell thrust sheets. To the southeast, some rocks in the 

Tallulah Falls thrust sheet probably correlate with units of 

the Ashland-Wedowee belt (Hurst, 1973). Odom and 

others (1976) presented Rb-Sr data that suggest some 

metasedimentary units of the Ashland-Wedowee belt were 

regionally metamorphosed about 370 Ma. Preliminary 

unpublished U-Pb zircon ages suggest that the regional 

metamorphism in the Tallulah Falls thrust sheet is probably no older than 351-373 Ma (T. Stern, written commun., 1986) and thus may represent the same metamorphic event reported by Odom and others. 

The age of regional metamorphism for the Inner 

Piedmont, which includes the Chauga-Walhalla thrust 

complex, the Six Mile thrust sheet, and the Laurens thrust 

sheet in the Greenville quadrangle, is also incompletely 

understood. To the northeast, rocks of these thrust sheets 

appear to be on strike with Inner Piedmont rocks that 

were regionally metamorphosed between 410 and 430 Ma 

(Butler, 1972), but to the southwest, the rocks of these 

thrust sheets extend into and form the Inner Piedmont 

terrane that Dallmeyer (1978) suggests was metamorphosed about 365 Ma. 

Preliminary, radiometric dating studies suggest that 

rocks of the Chauga-Walhalla thrust complex were not 

regionally metamorphosed earlier than about 400-424 

Ma (T. Stern, written commun., 1986), and these studies 

agree well with Butler's (1972) age of Inner Piedmont 

metamorphism at 410-430 Ma, but these rocks could also 

have been regionally metamorphosed during the 365 Ma 

event of Dallmeyer. Preliminary U-Pb zircon ages suggest 

that regional metamorphism for the eastern part of the 

Six Mile thrust sheet occurred no earlier than about 

365-391 Ma (T. Stern, written commun., 1986). These 

limits suggest a closer correspondence to the 365 Ma 

regional metamorphism date of Dallmeyer. Preliminary 

U-Pb zircon dating for rocks in the Laurens thrust sheet 

suggests that regional metamorphism occurred no earlier 

than about 344-359 Ma (T. Stern, written commun., 

1986). This seems to preclude using the 410-430 Ma for 

metamorphism of the Laurens thrust sheet that Butler 

used for the Inner Piedmont farther to the north. The 

344-359 Ma for metamorphism is closer to and may be a 

late stage of the 365 Ma event of Dallmeyer (1978). 

Within the Greenville quadrangle, the Inner Piedmont is bounded on the northwest by the Brevard zone, 

which separates the Tallulah Falls thrust sheet on the 

northwest from the Chauga-Walhalla thrust complex on 

the southeast. Farther to the southwest in Georgia and 

Alabama, the Brevard zone does not form a major 

terrane boundary, as some rock units from the AshlandWedowee belt extend from the west across the Brevard 

zone and into the Inner Piedmont (Medlin and Crawford, 

1973). Because of this, Dallmeyer has pointed out that the 

Ashland-Wedowee belt and some rocks of the Inner 

Piedmont were probably regionally metamorphosed about 

365-370 Ma. 

Butler (1972) suggests that belts southeast of the 

Inner Piedmont and east and northeast of the Greenville 

quadrangle were regionally metamorphosed between 380 

and 420 Ma. In the Greenville quadrangle, rocks underlying the Charlotte thrust sheet (fig. 1) lie immediately 

southeast of the Inner Piedmont along the Lowndesville 

shear zone. Preliminary U-Pb zircon studies suggest that 

the Charlotte thrust sheet was regionally metamorphosed 

approximately 312-338 Ma (T. Stern, written commun., 

1986), and here the age of regional metamorphism does 

not correspond with the 380-420 event farther to the 

northeast. Medlin (1968) reported that postmetamorphic 

plutons in the Charlotte thrust sheet have K-Ar age dates 

of 380, 386, and 387 Ma. These dates appear anomalous; 

they do not correspond with recent U-Pb zircon dates, but 

they do correspond with the 380-420 Ma event of Butler 

(1972). 

Fullagar and Kish (1981) presented Rb-Sr mineral 

age data for a part of the Inner Piedmont, represented by 

the Laurens thrust sheet, the Paris Mountain thrust sheet, 

and the Charlotte thrust sheet. These Rb-Sr mineral ages, 

within the report area, range from 254 to 280 Ma. The 

Fullagar and Kish study shows that the youngest mineral 

ages are in the western part, and they suggest that this 

12 Thrust Sheets and Regional Metamorphism, Georgia, South Carolina-A Reinterpretation 
results from more recent uplift and erosion of the rocks 

underlying the western Piedmont. The 254-280 Ma mineral ages (Permian) for parts of the Laurens thrust sheet, 

the Paris Mountain thrust sheet, and the Charlotte thrust 

sheet are probably the results of rapid cooling of an 

earlier thermal event. Throughout the Greenville quadrangle, several postpeak regional-metamorphic stages of 

cleavage development and mica crystallization exist in 

these cleavage planes. I suggest that Permian mineral 

ages might represent slightly earlier, but postregional, 

metamorphism thermal-deformation events that may not 

have been very intense nor extensively developed. 

CONCLUSIONS 

While the precise timing of regional metamorphic 

events in specific thrust sheets within the Greenville 

quadrangle is imperfectly known, the following pattern 

seems to be present. The oldest regional metamorphic 

event, exclusive of the Middle Proterozoic event in the 

basement rocks, occurs in the rocks of thrust sheets 

northwest of the Tallulah Falls thrust sheet (fig. 5). The 

youngest prograde metamorphic event appears to be in 

the rocks of the Charlotte thrust sheet in the southeast 

part of the quadrangle. Generally the Chauga-Walhalla 

thrust complex, the Six Mile thrust sheet, the Laurens 

thrust sheet, and the Charlotte thrust sheet appear to 

have been regionally metamorphosed at successively 

younger intervals from west to east. 

Rocks that compose the thrust sheets northwest of 

the Tallulah Falls thrust sheet appear to have been 

regionally metamorphosed during the Paleozoic between 

430 and 470 Ma (Butler, 1972) (fig. 5). Immediately to 

the southeast, rocks of the Tallulah Falls thrust sheet seem 

to have been metamorphosed between 365 and 370 Ma. 

Next to the southeast, in the Inner Piedmont, rocks of the 

Chauga-Walhalla thrust complex could have been metamorphosed either during the 410-430 Ma event of Butler 

(1972) for the Inner Piedmont or during the 365 Ma event 

for the Inner Piedmont to the south (Dallmeyer, 1978). 

Rocks of the Six Mile thrust sheet were probably metamorphosed during the 365 Ma event suggested by Dallmeyer. The Laurens thrust sheet appears to have been 

metamorphosed no earlier than 344 Ma or during a later 

phase of the 365 Ma event. The rocks of the Charlotte 

thrust sheet exposed in the Greenville quadrangle were 

probably regionally metamorphosed between 312 and 

338 Ma. 

At the present time, a sketchy and imperfect understanding exists of the metamorphic and deformational 

history of the thrust sheets underlying the Greenville 

quadrangle. The distribution and position, as well as the 

present metamorphic grade and age, of the thrust sheets 

underlying the Greenville quadrangle show that they have 

evolved through a complex deformation and metamorphic 

history. Thrust sheets with varying ages and grades of 

metamorphism are juxtaposed, and some thrust sheets 

have anomalous ages of metamorphism. Deformation 

along some of the major thrust faults covers a long time 

interval; some faults are pre- to synmetamorphic, and 

parts of some earlier faults appear to have been reactivated later under a brittle regime. I suggest that the 

present distribution of the thrust sheets results &om 

telescoping of previously metamorphosed thrust sheets 

during a long interval of intermittent westward transport 

of much of the thrust stack onto the North American 

craton during the Paleozoic and that selected assemblages 

of thrust sheets were metamorphosed during one of 

several metamorphic events and assembled into their 

present position as outlined below. 

The Helen thrust sheet was emplaced upon the 

Great Smoky thrust sheet before the 430-470 Ma regional 

metamorphic event. Later, during an interval that began 

before, but extended into, the period of regional metamorphism, the Richard Russell thrust sheet and the 

Young Harris slice were thrust over bOth the Helen and 

the Great Smoky thrust sheets along the Hayesville fault. 

The Hayesville fault is a pre- to synmetamorphic fault, 

but some postmetamorphic movement along the fault 

between the Richard Russell and Helen thrust sheets has 

occurred (Nelson, 1985), perhaps as a back thrust. The 

Great Smoky thrust sheet, the Helen thrust sheet, and the 

Richard Russell thrust sheet, along with the Young Harris 

slice, form a northwest thrust sheet assemblage that was 

metamorphosed 430-470 Ma. 

The metamorphosed Tallulah Falls thrust sheet was 

emplaced upon the Helen thrust sheet along the Dahlonega fault probably before 356 Ma. In places, lo\ver grade 

rocks (garnet zone) of the Helen thrust sheet are juxtaposed with migmatite and sillimanite grade rocks of the 

Tallulah Falls thrust sheet; this juxtaposition suggests that 

the two thrust sheets were separated during metamorphism of the Tallulah sheet that occurred about 365 Ma. 

Rock units of the Chauga-Walhalla thrust complex 

were metamorphosed between 365 and 430 Ma (fig. 5). 

The preferred date is close to 365 Ma because rocks of 

this thrust complex are close to and probably correlate 

with some rocks that Dallmeyer (1978) indicates were 

metamorphosed 365 Ma. The Six Mile thrust sheet was 

also metamorphosed at approximately the same time, 

while the Paris Mountain and the Laurens thrust sheets 

were metamorphosed slightly later, about 344 Ma. Thrust 

sheets of the Inner Piedmont exposed between the 

Brevard zone and the Lowndesville shear zone form a 

distinct thrust sheet assemblage considered to have been 

metamorphosed during the same event that extended 

&om 344 to 365 Ma. The Chauga-Walhalla thrust complex, which forms the northwest part of this thrust sheet 

assemblage, was thrust onto the Tallulah Falls thrust sheet 

Conclualona 13 
along the Brevard zone about 356 Ma ( Odom and 

Fullagar, 1973) when the mylonites and blastomylonites 

of the Brevard zone formed. Subsequently rocks in the 

Brevard zone were brittly deformed over a long inteJVal. 

The Six Mile thrust sheet was thrust onto the 

Walhalla thrust sheet along an unnamed postmetamorphic fault. When the Laurens thrust sheet was emplaced 

onto the Six Mile sheet is unknown, but the Paris Mountain thrust sheet was emplaced after the Laurens and Six 

Mile sheets were joined. The metamorphosed and 

deformed Charlotte thrust sheet was thrust upon parts of 

the Six Mile and Laurens thrust sheets along the Lowndesville shear zone between 312 and 344 Ma. 

If the present interpretation is correct, the various 

thrust sheet assemblages were metamorphosed during 

one of three periods of regional metamorphism-312-338 

Ma, 344-365 Ma, or 430-470 Ma-younging from northwest to southeast. Except for the northwestermost assemblage, the thrust sheets or thrust sheet assemblages were 

metamorphosed before emplacement upon thrust sheets 

to the northwest. After the major thrust sheets or assemblages of thrust sheets were joined, they were thrust as a 

unit along a master decollement to their present position 

upon unmetamorphosed Paleozoic rocks of the Valley 

and Ridge near the close of the Paleozoic. 

REFERENCES CITED 

American Geophysical Union, 1964, Bouguer gravity map of 

the United States: Washington, D.C., U.S. Geological 

Suxvey, 2 sheets, scale 1:2,500,000. 

Bowen, B.M., Jr., 1961, The structural geology of a portion of 

southeastern Dawson County, Georgia: Atlanta, Ga., 

Emory University, unpublished M.S. thesis, 45 p. 

Butler, J.R., 1972, Age of Paleozoic regional metamorphism 

in the Carolinas, Georgia, and Tennessee southern 

Appalachians: American Journal of Science, v. 272, no. 

4, p. 319-333. 

Cook, F.A., Albaugh, D.S., Brown, L.D., Kaufman, Sidney, 

Oliver, J.E., and Hatcher, R.D., 1979, Thin-skinned tectonics in the crystalline southern Appalachians, 

COCORP seismic reflection profiling of the Blue Ridge 

and Piedmont: Geology, v. 7, no. 10, p. 563-567. 

Crickmay, G.W., 1952, Geology of the crystalline rocks of 

Georgia: Georgia Geological Suxvey Bulletin 58, 54 p. 

Dallmeyer, R.D., 1975, Incremental 40Ar/39Ar ages of biotite 

and hornblende from retrograded basement gneisses of 

the southern Blue Ridge-Their bearing on the age of 

Paleozoic metamorphism: American Journal of Science, 

v.275,no.4,p.444-460. 

--1978, 40 A/39 Ar incremental-release ages of hornblende and biotite across . the Georgia Inner Piedmont: 

Their bearing on late Paleozoic-early Mesozoic tectonothermal history: American Journal of Science, v. 278, no. 

2, p. 124-149. 

Dallmeyer, R.D., Courtney, P.S., and Wooten, R.M., 1978, 

Stratigraphy, structure, and metamorphism east of the 

Murphy syncline, Georgia-North Carolina: Georgia Geological Society, Field Trip Guidebook 17, 74 p. 

Davis, G J ., 1980, The southwest extension of the MiddletonLowndesville cataclastic zone in the Greensboro, Georgia area and its regional implications: Athens, Ga., University of Georgia, unpublished M.S. thesis, 151 p. 

Dupuis, R.H., 1975, Stratigraphy, structure, and metamorphic 

history of the northern half of the Nottely Dam quadrangle, Georgia-North Carolina: Athens, Ga., University of 

Georgia, unpublished M.S. thesis, 150 p. 

Eckert, J.O., and Mohr, D.W., 1985, Petrologic evidence for 

Paleozoic granulite facies metamorphism in the North 

Carolina Blue Ridge [abs.]: Geological Society of America Abstracts with Programs, v. 17, no. 7, p. 90. 

Fullagar, P.D., and Butler, J.R., 1979, 325 to 265 m.y.-old 

granitic plutons in the Piedmont of the southeastern 

Appalachians: American Journal of Science, v. 279, p. 

161-185. 

Fullagar, P.D., Hatcher, R.D., and Merschat, C.E., 1979,1200 

M.Y. old gneisses in the Blue Ridge province of North 

Carolina: Southeastern Geology, v. 20, no. 2, p. 69-77. 

Fullagar, P.O., and Kish, SA., 1981, Mineral age traverses 

across the Piedmont of South Carolina and North Carolina, in Carolina Geological Society Field Trip Guidebook, Geological Investigations of the Kings Mountain 

belt and adjacent areas in the Carolinas: Columbia, S.C., 

South Carolina Geological Society, p. 155-165. 

Furcron, A.S., and Teaque, K.H., 1943, Mica-bearing pegmatites of Georgia: Georgia Geological Suxvey Bulletin 48, 

p. 134-144. 

Galpin, S.L., 1915, A preliminary report on the feldspar and 

mica deposits of Georgia: Georgia Geological Suxvey 

Bulletin 30, 190 p. 

German, J.M., 1985, The geology of the northeastern portion 

of the Dahlonega gold belt: Georgia Geologic Suxvey 

Bulletin 100, p. 1-41. 

Gillon, K., 1982, Stratigraphic, structural, and metamorphic 

geology of portions of the Cowrock and Helen Georgia 

7 1/2' quadrangles: Athens, Ga., University of Georgia, 

unpublished M.S. thesis, 236 p. 

Grant, W .H., 1958, The geology of Hart County, Georgia: 

Georgia Geological Suxvey Bulletin 67, 75 p., scale 

1:48,000. 

Griffin, V.S., Jr., 1967, Geology of the Six Mile quadrangle, 

South Carolina: South Carolina Division of Geology 

Map Series MS-14, scale 1:24,000. 

--1970, RelevanL)' of the Dewey-Bird hypothesis of 

Cordilleran-type mountain belts and the Wegmann stockwork concept: Journal of Geophysical Research, v. 75, 

no.35,p. 7504-7507. 

--1971, The Inner Piedmont of the southern crystalline 

Appalachians: Geological Society of America Bulletin, v. 

82,no. 7,p. 1885-1898. 

--1973, Geology of the Old Pickens quadrangle, S.C.: 

South Carolina Division of Geology Map Series, MS-18, 

54 p., scale 1:24,000. 

--1974, Geology of the Walhalla quadrangle, S.C.: 

South Carolina Division of Geology Map Series, MS-19, 

53 p., scale 1:24,000. 

14 Thrust Sheets and Regional Metamorphism, Georgia, South Carolina-A Reinterpretation 
---1975, Geology of the Seneca, Westminster, and portions of the Avalon and Oakway quadrangles, S.C.: 

South Carolina Division of Geology Map Series, M~20, 

42 p., scale 1:24,000. 

---1977, Preliminary geologic map of the South Carolina 

Inner Piedmont belt: South Carolina Division of Geology Geologic Notes, v. 21, no. 4, p. 198-204. 

--1978, Geology of the Calhoun Creek, Calhoun Falls 

and portions of the Chennault and Verdery quadrangles: 

South Carolina Geological Survey Map Series, M~23, 

47 p., scale 1:24,000. 

--1979, Geology of the Abbeville East, Abbeville West, 

Latimer, and Lowndesville quadrangles: South Carolina 

Geological Survey Map Series, M~24, 58 p., scale 

1:24,000. 

--1981, Geology of the Anderson South, Hartwell NE, 

La France, and Saylors Crossroads (7.5 minute) quadrangles and the Anderson (15 minute) quadrangle, South 

Carolina: South Carolina Geological Survey Map Series, 

M~25, 28 p., scale 1:24,000. 

Hadley, J.B., and Goldsmith, Richard, 1963, Geology of the 

eastern Great Smoky Mountains, North Carolina and 

Tennessee: U.S. Geological Survey Professional Paper 

349-B, p. B1-B118. 

Hadley, J.B., and Nelson, A.E., 1971, Geologic map of the 

Knoxville quadrangle, North Carolina, Tennessee, and 

South Carolina: U.S. Geological Survey Miscellaneous 

Geologic Investigations Map I-654, scale 1:250,000. 

Harper, S.B., and Fullagar, P.O., 1981, Rb-Sr ages of granitic 

gneisses of the Inner Piedmont belt of northwestern 

North Carolina and southwestern South Carolina: Geological Society of America Bulletin, pt. 1, v. 92, p. 

864-872. 

Harris, L.D., and Bayer, K.C., 1979, Sequential development 

of the Appalachian orogen above a master decollement-A hypothesis: Geology, v. 7, no. 12, p. 568-572. 

Harris, L.D., Harris, A.G., and de Witt, Wallace, Jr., 1981, 

Evaluation of the southeastern overthrust belt beneath 

the Blue Ridge-Piedmont thrust: American Association 

of Petroleum Geologists Bulletin, v. 65, no. 12, p. 

2497-2505. 

Hartley, M.E., 1973, Ultramafic and related rocks in the 

vicinity of Lake Chatuge: Georgia Geological Survey 

Bulletin 85, 61 p. 

Hatcher, R.D., Jr., 1969, Stratigraphy, petrology, and structure of the low rank belt and part of the Blue Ridge of 

northwestemmost South Carolina: South Carolina Division of Geology Geologic Notes, v. 13, no. 4, p. 105-141. 

--1971, Geology of Rabun and Habersham Counties, 

Georgia-A reconnaissance study: Georgia Geological 

Survey Bulletin 83, 48 p. 

--1972, Developmental model for the southern Appalachians: Geological Society of America Bulletin, v. 83, no. 

9, p. 2735-2760. 

--1974, An introduction to the Blue Ridge tectonic history of northeast Georgia: Georgia Geological Society 

Field Trip Guidebook 13-A, 60 p. 

--1976, Introduction to the geology for the eastern Blue 

Ridge of the Carolinas and nearby Georgia: Columbia, 

S.C., Carolina Geological Society Guidebook, 53 p. 

--1978a, The Alto allochthon-A major tectonic unit of 

the northeast Georgia Piedmont, in Short contributions 

in the Geology of Georgia: Atlanta, Ga., Georgia Geological Survey, p. 83-86. 

--1978b, Tectonics of the western Piedmont and Blue 

Ridge, southern Appalachians-Review and speculations: American Journal of Science, v. 278, no. 3, p. 

276-304. 

--1979, The Coweeta Group and Coweeta SynclineMajor features of the North Carolina-Georgia Blue 

Ridge: Southeastern Geology, v. 4, no. 1, p. 17-29. 

Hatcher, R.D., Jr., and Acker, L.L., 1984, Geology of the 

Salem quadrangle, South Carolina: South Carolina Geological Survey Map Series, M~26, 23 p., scale 1:24,000. 

Hatcher, R.D., Jr., and Zietz, 1., 1980, Tectonic implications 

of regional aeromagnetic and gravity data from the 

southern Appalachians, in Wones, R.D., ed., Proceedings, The Caledonides in the U.S.A., IGCP Project 27-

Caledonide Orogen, 1979, meeting: Virginia Polytechnic 

Institute and State University Memoir 2, p. 235-244. 

Higgins, M.W., Atkins, R.L., Crawford, T J., Crawford, R.F., 

Jr., Brooks, Rebekah, and Cook, R.B., 1988, The structure, stratigraphy, tectonostratigraphy, and evolution of 

the southern part of the Appalachian orogen, Georgia 

and Alabama: U.S. Geological Survey Professional Paper 

1475. 

Higgins, M.W., Atkins, R.L., Crawford, TJ., Crawford, R.F., 

Jr., and Cook, R.S., 1984, A brief excursion through two 

thrust stacks that comprise most of the crystalline terrane of Georgia and Alabama: Atlanta, Georgia, Georgia Geological Society Guidebook, 67 p. 

Higgins, M.W., and Crawford, R.F., Jr., 1985, The Macon 

melange, an ancient subduction complex in the southern 

Appalachians, Alabama-North Carolina [abs.]: Geological Society of America Abstracts with Programs, v. 17, 

no 7, p. 610. 

Hopkins, O.B., 1914, Talc, asbestos, and soapstone deposits 

of Georgia: Georgia Geological Survey Bulletin 29, p. 

275-300. 

Horton, J.W., Jr., 1981, Shear zone between the Inner Piedmont and Kings Mountain belts in the Carolinas: Geology,v. 9, no. 1,p. 28-33. 

Hurst, V J., 1973, Geology of the southern Blue Ridge belt: 

American Journal of Science, v. 173, no. 10, p. 643-670. 

Kulp, J.C., and Eckelmann, F.D., 1961, Potassium-argon isotopic ages on micas from the southern Appalachians: 

New York Academy of Science Annals, v. 91, p. 

408-419. 

Long, L.E., Kulp, J.L., and Eckelmann, F.D., 1959, Chronology of major metamorphic events in the southeastern 

United States: American Journal of Science, v. 257, p. 

585-603. 

Long, L.K., and Miller, C.F., 1983, Chemistry, genesis and 

tectonic significance of the Lake Chatuge maficultramafic complex, North Carolina-Georgia [abs.]: Geological Society of America Abstracts with Programs, v. 

15, no. 3, p. 143. 

McConnell, K.L., and Costello, J.O., 1980, Guide to geology 

along a traverse through the Blue Ridge and Piedmont 

provinces of North Georgia, in Frey, R.W., ed., ExcurReferences Cited 15 
sions in southeastern geology, v. 1: Falls Church, Va., 

American Geological Institute, p. 241-257. 

Medlin, J.H., 1968, Comparative petrology of two igneous 

complexes in the South Carolina Piedmont: the Pennsylvania State University, Ph.D. dissertation, 328 p. 

Medlin, J.H., and Crawford, T.J., 1973, Stratigraphy and 

structure along the Brevard fault in western Georgia and 

eastern Alabama: American Journal of Science, v. 

273-A, no. 1, p. 89-104. 

Nelson, A.E., 1981, Polydeformed rocks of the Lowndesville 

shear zone in the Greenville 2° quadrangle, South Carolina and Georgia, in Carolina Geological Society Field 

Trip Guidebook, Geological Investigations of the Kings 

Mountain belt and adjacent areas in the Carolinas: 

Columbia, S.C., South Carolina Geological Society, p. 

181-193. 

--1982, Geologic map of the Tray Mountain Roadless 

Area, North Georgia: U.S. Geological Survey Miscellaneous Field Studies Map MF-1347-A, scale 1:30,000. 

--1983a, Geologic map of the Chattahoochee Roadless 

Area, Towns, Union, and White Counties, Georgia: U.S. 

Geological Survey Miscellaneous Field Studies Map 

MF-1502-A, scale 1:30,000. 

--1983b, Geologic map of the Blood Mountain Roadless 

Area, Union and Lumpkin Counties, Georgia: U.S. Geological Survey Miscellaneous Field Studies Map 

MF-1503-A, scale 1:30,000. 

--1985, Major tectonic features and structural elements 

in the northwest part of the Greenville quadrangle, 

Georgia: U.S. Geological Survey Bulletin 1643, 22 p. 

Nelson, A.E., and Gillon, K.A., 1985, Stratigraphic nomenclature in the Richard Russell and Helen thrust sheets, 

North Georgia, in Contributions to stratigraphy 1984: 

U.S. Geological Survey Bulletin 1605-A, p. A59-A62 

Nelson, A.E., Horton, J.W., Jr., and Clarke, J.W., 1986, Generalized tectonic map of the Greenville 1 °X 2° quadrangle, Ga., S.C., and N.C.: U.S. Geological Survey Miscellaneous Investigation Map, MF-1898, scale 1:250,000. 

Nelson, A.E., and Koeppen, R.P. 1986, Geologic map of the 

Overflow Roadless Area, Rabun County, Georgia, and 

Macon County, North Carolina: U.S. Geological Survey 

Miscellaneous Field Studies Map MF 1618-B, scale 

1:48,000. 

Nelson, A.E., and Zietz, Isidore, 1983, The Clingman lineament, other aeromagnetic features, and major lithotectonic units in part of the southern Appalachian Mountains: Southeastern Geology, v. 24, no. 3, 147-157. 

Odom, A.L., and Fullagar, P.D., 1973, Geochronological and 

tectonic relationships between the Inner Piedmont, 

Brevard zones, and Blue Ridge belts, North Carolina: 

American Journal of Science, v. 273-A, no. 2, p. 133-149. 

Odom, A.L., Russell, G.S., and Russell, C.W., 1976, Distribution and age of Precambrian basement in the southern 

Appalachians [ abs.]: Geological Society of America 

Abstracts with Programs, v. 8, no. 2, p. 238. 

Park, C.F., 1953, Gold deposits of Georgia: Georgia Geological Survey Bulletin 60, p. 60-67. 

Price, E.H., 1977, Stratigraphy, structure, and metamorphic 

history of the southern half of the Nottely Dam quadrangle, Georgia-North Carolina: Athens, Ga., University of 

Georgia, unpublished M.S. thesis, 200 p. 

Rankin, D.W., 1975, The continental margin of eastern North 

America in the southern Appalachians: The opening and 

closing of the Proto-Atlantic Ocean: American Journal 

of Science, v. 275-A, no. 3, p. 298-336. 

Rankin, D.W., Stern, T.W., Reed, J.C., Jr., and Newell, W.F., 

1969, Zircon ages of felsic volcanic rocks in the Upper 

Precambrian of the Blue Ridge, central and southern 

Appalachian Mountains: Science, v. 166, no. 3906, p. 

741-744. 

Roper, P J., and Dunn, D.E., 1970, Geology of the Tamassee, 

Satolah and Cashiers quadrangles, Oconee County, 

South Carolina: South Carolina State Development 

Board Division of Geology Map Series, MS-16, 55 p. 

Shaw, H.F., and Wasserburg, G.J., 1984, Isotopic constraints 

on the origin of Appalachian mafic complexes: American 

Journal of Science, v. 284, nos. 4 and 5, p. 319-349. 

Shellebarger, J.E., 1980, A preliminary report on the geology 

of the Coosa Bald and Jack's Gap quadrangles, Georgia: 

Athens, Ga, University of Georgia, unpublished M.S. 

thesis, 209 p. 

Sibson, R.H., 1977, Fault rocks and fault mechanisms: Journal of the Geological Society of London, v. 133, no. 2, p. 

191-213. 

Stanton, R.L., 1976, Petrochemical studies of the ore environment at Broken Hill, New South Wales: 1, Constitution of "banded iron formations": Transections of the 

Institution of Mining and Metallurgy, sec. B, v. 85, p. B 

33-B 46. 

Whitney, J.A., Jones, L.M., and Walker, R.L., 1976, Age and 

origin of the Stone Mountain granite, Lithonia district, 

Georgia: Geological Society of America Bulletin, v. 87, 

p. 1067-1077. 

Williams, Harold, 1978, Tectonic lithofacies map of the 

Appalachian Orogen: St. Johns, Memorial University of 

Newfoundland, scale 1:1,000,000. 

Wooten, R.M., 1980, Geology of the southern half of the 

Hayesville quadrangle, North Carolina: Athens, Ga., 

University of Georgia, unpublished M.S. thesis, 254 p. 

Yeates, W.S., and McCallis, S.W., 1896, The gold deposits of 

Georgia: Georgia Geological Survey Bulletin 4, 542 p. 

Zen, E-an, 1981, An alternative model for the development 

of the allochthonous southern Appalachian Piedmont: 

American Journal of Science, v. 281, no. 9, p. 1153-1163. 

16 Thrust Sheets and Regional Metamorphism, Georgia, South Carolina-A Reinterpretation 
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