For many years, the question regarding what happens to the rocks of the Talladega belt in the vicinity of their apparent northeastern terminus near Cartersville has been the subject of controversy. This has coincided with the debate over the age and correlation of metasedimentary rocks that overlie the billion-year-old Corbin gneiss complex to the east of Cartersville. Both of these problems are interrelated, and the resolution of each is dependent on the other. Stratigraphic relationships in the polydeformed rocks exposed in the Salem Church anticlinorium east of Cartersville indicate that the rocks unconformably overlying the Corbin gneiss complex are lithostratigraphic equivalents of the lowermost Ocoee Supergroup. These lithologies can be traced southwestward to the area east of Emerson where the Talladega belt has been presumed to end. Here, it is evident from studying the small- and large-scale structural features that folding has played an important role in the structural and stratigraphic complications that occur. Our mapping suggests that although part of the Ocoee Supergroup does disappear southwest of Cartersville because of folding, other parts of the Ocoee continue on to the southwest and into the Talladega belt. In the Talladega belt of Alabama, rock units such as the Heflin Phyllite, Abel Gap Formation, and Lay Dam Formation are lithologically similar but may be much younger than parts of the lowermost Ocoee Supergroup sequence present in Georgia. Other rock units of the Talladega belt in Alabama also resemble parts of the Ocoee sequence, but they too are not directly relatable to the Ocoee. AH long-range correlations can be considered only speculative until detailed mapping in western Georgia and eastern Alabama is completed. However, there is evidence to suggest that at least part of the Talladega belt is Precambrian in age and was deposited synchronously with the Ocoee Supergroup.

Talladega “Series” rock units in Polk and Paulding Counties have been mapped through the Cartersville area along the southeastern fault boundary of the “Corbin granite complex,” and correlated with rock units of the Great Smoky Group in Cherokee County. The Talladega “Series” in this area is bounded on the northwest by the Emerson (Cartersville) fault, along which the Talladega was thrust over (1) Valley and Ridge rocks ranging in age from Early Cambrian (Chilhowee Group) to Mississippian (Fort Payne Chert), (2) the Ocoee Supergroup, and (3) the “Corbin granite complex.” The Emerson fault also overrode the Great Smoky fault, which separates Ocoee from Chilhowee rocks in the Cartersville area. The thrust fault along the southeastern boundary of the Talladega “Series” is only one of numerous closely spaced imbricate faults within and southeast of the Talladega. The presence of closely spaced thrusts within the Talladega, the association of Hillabee Chlorite Schist-“Pumpkinvine Creek” lithologies with many of these faults, and the fact that detailed mapping has not been completed between the Rockmart-Yorkville area and the Alabama state line emphasize the need for caution in projecting correlations and interpretations across this area.

The Talladega belt in Alabama and Georgia is the northwesternmost belt of the Appalachian Piedmont metamorphic province. It contains low-rank metasediments and metavolcanics that have been thrust faulted onto Paleozoic sediments of the Valley and Ridge province via the Cartersville-Talladega fault system. The age of several formations in the southwestern part of the Talladega belt in Alabama has been determined to be Devonian, but controversy exists concerning the age of much of the rest of the belt. Another major problem has been the age and structure relationships of the Talladega belt to the Precambrian and Lower Cambrian rocks of the Blue Ridge province on strike with the Talladega belt to the northeast. In the Borden Springs area, Cleburne County, Alabama, nappes of the Lower Cambrian Weisner and Shady Formations rest on younger Paleozoic rocks immediately northwest of the Talladega belt. A sequence composed mainly of slates and quartzites characterized by graded beds lies between the Talladega belt and the nappes of Weisner and Shady. Distinctive lithologies within this sequence are found also within the Talladega belt near Borden Springs and also near the southwest end of the belt in Alabama within metasediments immediately below the Jumbo Dolomite of the Sylacauga Marble Group. Although the slate-quartzite sequence has been interpreted in recent years as being Ordovician to Devonian, detailed mapping in the Borden Springs area indicates that it is correlative with the Early Cambrian Weisner and Shady, although somewhat different in sedimentary aspect from Weisner and Shady in nappes to the west. Therefore, the Talladega belt may contain rocks at least as old as Early Cambrian and may be at least partly equivalent in age to rocks of the Blue Ridge province. The slate-quartzite sequence lies northwest, west, and southeast of an anticlinal region of younger Paleozoic sediments in western Georgia, over which it was thrust faulted. It thus forms an imbricated nappe sequence rooted, if at all, beneath the Piedmont province to the southeast.

The Talladega slate belt in eastern Alabama represents a crystalline thrust sheet composed of low-grade metasediments. Three major lithologic sequences comprise the Talladega slate belt: (1) the Kahatchee Mountain Group, (2) the Sylacauga Marble Group, and (3) the Talladega Group. The contact relationships between the Sylacauga Marble Group and the Talladega Group indicate that the phyllites and slates of the Talladega Group rest unconformably on marbles of the Sylacauga Marble Group. Previous workers have identified specific stratigraphic sequences within the Talladega Group both in the north-central portion of the Talladega slate belt and in the southern portion of the belt. Little work has been carried out in the south-central portion of the Talladega slate belt, a region intermediate between areas to the northeast and southwest where the regional stratigraphy has been defined. To the northwest in Cleburne and Clay Counties, Alabama, the Talladega Group has been broken down into the Heflin Phyllite, the Able Gap Formation, and the Chulafinnee Schist. To the southwest in Chilton County, Alabama, similar units have been mapped as the Lay Dam Formation, the Butting Ram Sandstone, and the Jemison Chert. These units have not been mapped through this intermediate south-central region of the Talladega slate belt because of the absence by faulting of a major sandstone unit, the Cheaha Quartzite, which has been used for regional correlation. Another prominent unit, the Jemison Chert, which outcrops to the southeast of the Cheaha Quartzite, continues across this region and was used to correlate the regional stratigraphy from the northeast with that in the southwest. Detailed mapping has shown that a small slice of paper-thin quartzites of the Jemison Chert interval has overridden the Cheaha Quartzite. The geometric relationships between these two units, the differing petrologic character of these ridge-forming lithologies, the duplication of the Jemison Chert interval, and the emplacement of this imbricate slice of Jemison, in addition to structural fabric data, suggest that this termination of the Cheaha Quartzite is fault related.

A major carbonate sequence occurs within the lower part of the Talladega slate belt in Chilton, Coosa, and Talladega Counties. The carbonate units are overlain by a major regional unconformity known as the pre-Lay Dam Formation unconformity. The carbonate sequence below the unconformity is represented in different areas by the Jumbo Dolomite, the Marble Valley carbonates, and the Sylacauga marbles. At the type location in Chilton County, the Jumbo is a 67-m-thick, predominantly thickly bedded dolostone. The contact with the underlying slates of the Wash Creek Slate (Mount Zion Formation) is an interlayered zone of dolostone and fine, commonly graphitic, clastic rock. This zone grades upward into a dolostone that contains a few pelitic layers. Near the base, the Jumbo contains intraclasts and recrystallized fragments up to 6 cm in length. Rounded quartz grains are disseminated in the lower section of the Jumbo. Near the middle of the massively bedded dolostone is a layer that contains intraclasts of massive and laminated carbonate as much as 12 cm in length. Just below the unconformity in the type section, the upper part of the Jumbo contains laminations of fine-grained clastic rock. Along strike to the northeast and southwest the unconformity appears to have erosional relief. Less than 1 km west of the type location the unconformity truncates the carbonate sequence completely. To the northeast the pre-Lay Dam Formation unconformity appears to rise in the section in the Marble Valley carbonates and the Sylacauga marbles, exposing a very thick carbonate sequence. Stratigraphic and structural relationships of the Jumbo, Marble Valley, and Sylacauga marbles are not yet resolved. Initial data indicate that the Jumbo occurs stratigraphically below and to the northwest of the Marble Valley carbonates, suggesting that the Jumbo is the oldest carbonate unit in the sequence.

The age of the Erin Shale, Clay County, Alabama, has been variously interpreted based primarily upon the acceptance or rejection of the original Carboniferous age assignment. The failure to confirm the in-place occurrence of the reported Pennsylvanian megafossils, coupled with both regional and detailed mapping, has led to the recent placement of the Erin Shale in a stratigraphically equivalent position with the Lay Dam Formation of inferred Early Devonian age. An investigation of the previously illustrated Carboniferous fossils reportedly collected from the Erin Shale and suites of rock specimens collected during the present study has added new pieces to the Erin puzzle but has not resolved the age asignment problem. Petrographic and x-ray diffraction powder analyses of the adhering matrix on Lepidostrobus hobbsii D. White and phyllites collected from the Erin outcrop belt indicate that these rocks are similar if not indistinguishable. Identifiable coal fragments exist in the Erin as do poorly preserved, unassignable fossil plant fragments. Much additional work is needed to fully define the fossiliferous nature of the Erin.

The Hillabee Greenstone is a mafic metavolcanic sequence at the stratigraphic top of the Talladega Group in the Northern Alabama Piedmont. The Hollins Line fault forms the upper contact of the Hillabee, and an undetermined amount of the Greenstone has been removed by faulting. The igneous protolith consisted of tholeiitic rocks (ash and lava) with minor calc-alkaline dacites. Volcanism was arc-related, based on geochemical evidence and the associated lithologies. Greenschist facies metamorphism and alteration have resulted in changes in the chemistry and mineralogy of the rocks. However, a variety of remnant igneous textures can be observed, and through statistical means, samples that have experienced minimal alteration can be identified, thereby allowing some of the igneous evolution of the Hillabee to be deduced. The chemistry and mineralogy (norm and mode) indicate tholeiitic fractionation representative of relatively shallow crustal depths with typical enrichment in Fe, V, Ti, and quartz and depletion of Mg, Cr, Ni, Co, and olivine. The dacites are associated with more highly fractionated basalts but do not appear to be a direct product of fractionation from the basalts. Some mafic rocks are typically gabbroic in texture and are interpreted to represent lava flows. Geochemical and field evidence indicates that the exposed Hillabee Greenstone represents an immature arc; plagioclase and olivine were highly fractionated prior to extrusion, and early stages of fractionation are not represented in surface exposures. Temporally earlier volcanics may occur downdip to the southeast toward the volcanic source; the exposed Hillabee Greenstone represents volcanics deposited somewhat distally from the volcanic source on the edge of the basin.

Slate belt rocks of southern Chatham and northern Moore Counties, North Carolina, constitute an overlapping series of metamorphosed volcanic and volcaniclastic strata reflecting three distinct sites of volcanic activity separated in time, space, and composition. At the base of the section, felsic volcanic and epiclastic rocks had a northeastern source. Subsequently, deposition was dominated by a center of relatively mafic (50 to 57 wt% SiO 2 ) volcanism to the northwest. Accretionary lapilli and sedimentary structures indicate subaerial to shallow subaqueous conditions in the north; southward decrease in grain size and changes in structures suggest deposition on the deeper-water slopes of the volcanic edifice. A still younger site of felsic (68 to 75 wt% SiO 2 ) volcanism abruptly developed on the southern flank of the waning mafic eruptive complex; local depositional paleoslope reversed, as felsic flows and tuffs interfingered northward with banded mudstones. The bimodal igneous rock geochemistry is consistent with the stratigraphic model. Low K/Na (K 2 O/Na 2 O < 0.2) may reflect alteration and metamorphism; some (more stable) minor and trace elements suggest calc-alkalic affinities.

A phyllite unit from the Carolina slate belt of South Carolina contains sponge spicules. The sponge spicules, which occur along bedding planes, are of three types: hexactines, tetraclads, and monactines. Even though the overall morphology of the spicules is very simple, they suggest a Middle Cambrian or younger age. The discovery of sponge spicules and recent discoveries of trilobites and metazoan trace fossils demonstrate that the Carolina slate belt is probably comprised of late Precambrain to Middle Ordovician metasediments.

This study documents an eruptive center, the instrusive Flat River complex and associated Carolina slate belt volcanic rocks near Durham, North Carolina. The zircon Pb/U age of the granite, granodiorite, quartz diorite, gabbro Flat River complex is 650 ± 30 m.y. Local vent breccias, chilled and protoclastically deformed margins, and petrographic comparisons with the experimental results in the qz-ab-or system confirm that the Flat River complex was emplaced at a depth of less than 1 km and was locally surface breaking. Thus, the Flat River can be viewed as a very shallow fossil volcanic magma chamber and may be typical of many granitoid plutons in the Carolina slate belt. The Flat River was intruded into a pile of coarse, near-vent pyroclastic deposits and lavas of felsic to intermediate composition. Intercalated in these is an exhalative unit of thinly layered to laminated metachert and iron oxide. Shallow to deep (or quiet) probably marine conditions prevailed. Some subaerial pyroclastic rocks may be present in the older parts of this >650-m.y. to 620-m.y.-old sequence of volcanic rocks.

A geochronological study of the Lincolnton metadacite, a prominent unit in the slate belt along the Georgia-South Carolina border, provides indicated primary ages of 554 ± 20 m.y. (Rb-Sr) and 568 m.y. (U-Pb, zircon). On the basis of both lithological and geochronological data, the Lincolnton metadacite and associated felsic pyroclastic sequence are interpreted to be correlative with the Uwharrie Formation in the Albemarle-Denton-Asheboro area of North Carolina. On the basis of lithologic comparison alone, the Lincolnton metadacite and associated felsic pyroclastic sequence are also interpreted to be equivalent to the Persimmon Fork Formation near Columbia, South Carolina. Prominent argillite units that overlie felsic metavolcanics in all three areas are likewise considered correlative. These units include the Tillery Formation (Albemarle-Denton-Asheboro area), the Richtex Formation (Columbia, South Carolina, area), and the upper sedimentary sequence (Lincolnton, Georgia-McCormick, South Carolina, area). Available data suggest a Cambrian age for most of these units, although some of the lowermost formations could actually be of very late Precambrian age.