Northward extension of carolina slate belt stratigraphy and structure, south-central virginia: Results from geologic mapping

The Carolina slate belt (CSB) is located in the southeastern Appalachian Piedmont, cropping out as a narrow continuous zone extending from central Virginia southwestward to central Georgia. Geologic investigations of the CSB began in the 1820s, shortly after discovery of gold in Cabarrus County, North Carolina. Early workers established the general distribution and character of the CSB relative to adjacent belts, and more recently, mappable units have been delineated. Present interest in the CSB is in part due to recognition of similarities between slate-belt rocks and those associated with sulfide deposits in New Brunswick, and in part to the recent recognition of sedimentary features in the relatively underformed slate-belt rocks. End_Page 1437------------------------------ Early workers in the CSB recognized the volcanic origin of slate-belt rocks, as well as subsequent metamorphic alteration. More recently, the sedimentologic-stratigraphic aspects of the CSB have been investigated. Interpretations of tectono-sedimentary environments have been made, based on petrologic, geochemical, and stratigraphic relationships, in light of the articulation of the concepts of plate tectonics and accreted terranes. Age interpretations of the CSB have been based on degree of metamorphism, radiochronology, and sparse fossil evidence. Age interpretations in the late 1800s and early 1900s suggested a Precambrian age for the CSB. This was modified in the 1960s by the discovery of a purported Middle Cambrian trilobite and a lead-alpha date of 440 to 470 ± 60 Ma. Post-1960s radiometric dates for the CSB range from 705 ± 15 Ma to 511 ± 14 Ma, representing various postdepositional intrusion and cooling events. The discovery of a mid-Cambrian Atlantic province trilobite fauna and upper Precambrian Ediacarian fossils not only unequivocally date the southern part of the CSB, but also support the accreted terrane concept and Euro-African origin of sedimentary units of CSB. End_of_Article - Last_Page 1438------------

A nearly concordant U-Pb zircon age of 550 ± 4 Ma is interpreted to closely date crystallization of the epizonal Little Mountain metatonalite in the southeastern part of the Charlotte belt in South Carolina. This confirms field studies which indicate that the Charlotte belt contains a plutonic metaigneous complex that developed as a sub-volcanic-arc infrastructure, contemporaneous with vulcanism manifested in the Carolina slate belt. Both paleontological and geochronological controls indicate that the South Carolina slate belt is mostly younger than 570 Ma (Cambrian?), whereas the slate belt in North Carolina and Virginia is mostly of late Proterozoic age. A regionally significant mid-Paleozoic (ca. 340–360 Ma) thermal event is suggested by discordant 40Ar/39Ar whole-rock age spectra of slate/phyllite in the northwestern Carolina slate belt and from hornblende in the southeastern Charlotte belt. It is uncertain if this event was associated with deformation in the eastern Piedmont; however, mid-Paleozoic deformation has been previously documented elsewhere in the western Piedmont. A slightly disconcordant U-Pb zircon age of 317 ± 4 Ma is interpreted to closely date initial crystallization of the deformed Edge-field granite and confirms a record of late Paleozoic penetrative deformation in the Kiokee belt of South Carolina. U-Pb isotope data for the Lake Murray orthogneiss and Clouds Creek granite are discordant and suggest that the magmas of these plutons were derived by partial melting of a sialic Precam-brian source and then emplaced in the eastern Piedmont at ca. 315 Ma (prior to or during the early stages of the Alleghanian orogeny). The thermal maximum of Alleghanian regional metamorphism (amphibolite facies in the Kiokee belt; greenschist facies in the southeastern part of the Carolina slate belt) occurred during ca. 295–315 Ma. During the late Carboniferous and Early Permian, the eastern Piedmont experienced differential uplift, erosion, and relatively rapid postmeta-morphic cooling. Isothermal surfaces were folded into an antiform-synform-antiform configuration corresponding to the Kiokee, Carolina slate, and Charlotte belts, respectively. The geochronological data provide the following calibration for the late Paleozoic deformational chronology recorded in the Kiokee and Carolina slate belts: D2 (Lake Murray deformation), ca. 295–315 Ma; D3 (Clarks Hill deformation), ca. 285–295 Ma; and D4 (Irmo deformation), ca. 268–290 Ma.

The Carolina slate belt includes volcanic and sedimentary rocks of Late Precambrian and Cambrian age, metamorphosed to lower greenschist facies, that extend through the Piedmont from Georgia to Virginia. The segment in central North Carolina (Fig. 1) is probably the best-known part of the belt. Rocks in the Albemarle area are mildly deformed and metamorphosed; the dominant structures are open folds plunging southwest and the regional metamorphism is chlorite and biotite grade. The Albemarle region includes type localities for several stratigraphic units. The localities described here are on the Albemarle (Conley, 1962) and Denton (Stromquist, Choquette, and Sundelius, 1971) 15-minute quadrangles. The guidebook by Stromquist and Conley (1959) marked the beginning of modern studies in the central Carolina slate belt, as they demonstrated that stratigraphy and structure could be worked out on a regional basis. Conley and Bain (1965) applied formation names to the section in the Albemarle area (Fig. 2) and extended this stratigraphic nomenclature through most of the slate belt in North Carolina. In the Albemarle region, a thick, dominantly felsic volcanic unit (Uwharrie Formation) is overlain by a dominantly sedimentary sequence (Albemarle Group). The Morrow Mountain Rhyolite and Badin Greenstone of the Tater Top Group were interpreted to be the uppermost units and to lie with angular unconformity above folded older units (Conley and Bain, 1965). Stromquist and Sundelius (1969) reinterpreted part of the middle and upper stratigraphic sequence. They considered the Tater Tbp Group to be interlayered with other units of the Albemarle Group, rather than

Felsic volcaniclastic rocks and massive pyrite of a part of the Carolina slate belt in South Carolina referred to as the “Haile-Brewer block” seem to have remained closed systems with respect to U, Th, and Pb since ∼465 Ma. U-Pb and Th-Pb whole-rock isochrons indicate ages of 466 ± 40 (2σ) and 462 + 53 Ma, respectively. The Pb-Pb secondary isochron age of the volcaniclastic rocks is ∼455 Ma. Because of the divergent ways in which U, Th, and Pb have behaved during the various alteration events that have affected the Haile-Brewer block (metamorphism, post-tectonic intrusion, weathering), the isochronous relationships most likely represent the emplacement age of the rocks. The preservation of U-Pb and Th-Pb isochrons is thought to be due to the originally glassy nature of the volcaniclastic rocks and to the relatively impermeable character of the rocks, which may have been aided by the sealing of pore space by infiltration of penecon-temporaneous, silica-rich hydrothermal fluids. The U-Pb and Th-Pb whole-rock ages are considerably younger than the ⩾550-Ma age inferred from U-Pb zircon ages and Ediacaran fossil assemblages for the slate belt in North Carolina. The younger ages agree, however, with the presence of sponge spicules no older than Middle Cambrian in the Haile-Brewer block. The younger age of the Haile-Brewer block with respect to other parts of the Carolina slate belt indicates that the belt is more complex than has been thought.

The Carolina slate belt consists of Precambrian-Cambrian, metamorphosed, mafic to felsic flows, volcaniclastics, and derived sediments which filled in a volcanic trough presumed to have formed along the leading edge of the North American continent during the early closing of the proto-Atlantic Ocean. Within the slate belt, in central North Carolina, South Carolina, and on the South Carolina-Georgia line, there are volcanigenic massive sulfide deposits of Kuroko affinities and their metamorphically remobilized sulfide and Au quartz deposits.A total of 296 chemical analyses of volcanic rocks and associated dikes (of which 227 are in unpublished theses, dissertation, and reports) are plotted on alkali-SiO 2 , K 2 O-Na 2 O, AFM, and Na 2 O-K 2 O-CaO diagrams. In addition, selected subsets are compared with standard discriminant plots, such as TiO 2 -SiO 2 , MgO-FeO total -Al 2 O 3 , and Y-Zr-Ti. Generally speaking, the volcanics of the slate belt define a bimodal suite of calc-alkaline to tholeiitic rocks with strong affinities to volcanic suites described in the lesser Antilles and with the volcanics of the coastal volcanic belt of Maine. A subduction-related orogenic environment is most probable.In addition, the major element analyses strongly suggest that a pervasive, postdepositional alteration process has taken place. In general, this alteration appears to have affected the fine-grained matrix of the volcaniclastics, but flows and dikes were not immune. An overall alkali depletion and MgO enrichment is characteristic, with significant, but variable, mobility of Na 2 O, K 2 O, CaO, and SiO 2 . Thus, characterization of the magmatogenesis by major element composition alone is not easily done. Alteration associated with massive sulfide mineralization in the Gold Hill district, North Carolina, and the Lincolnton-McCormick district, South Carolina-Georgia, is similar to, but more intense than, the pervasive secondary alteration. Strong silicification, alkali addition or subtraction, and MgO enrichment is characteristic. In general, a significant proportion of the mineralization-associated alteration falls outside the normal range of compositional variability of typical slate belt suites and, thus, has a notable signature.

Several epigenetic mineral deposits in the Ca1rolina slate belt are intimately related to meteoric-hydrothermal systems of late Precambrian and early Paleozoic age. At Pilot Mountain, low 18 O rocks correlate well with zones of strong silicic alteration and alkali leaching accompanied by high alumina minerals (sericite, pyrophyllite, andalusite + or - topaz) and anomalous concentrations of Cu, Mo, Sn, B, and Au. The alteration occurs within andesitic volcanic and volcaniclastic rocks and is associated with a subvolcanic(?) dacite porphyry stock on the southeastern slope of the mountain. Tilting and erosion have exposed an oblique section through the original system, interpreted to expose shallower rocks to the northwest. A 4-km 2 central zone of slight 18 O depletion (delta 18 O (sub whole rock) = 4.3-6.1ppm) occurs on the broad and resistant (silicifled) western flank of Pilot Mountain, predominantly within quartz-sericite schist and quartz granofels containing pods of high A1 minerals. A magmatic source for much of the sulfur and metal is likely, and a subordinate magmatic water component in the fluid of the central zone is possible. This central zone is surrounded by a >30-km 2 peripheral zone of low 18 O sericite schists, chlorite-sericite schists, and andesitic volcanic rocks (delta 18 O (sub whole rock) < 3.8ppm), with the lowest values (1.4ppm) occurring in intensely sericitized rocks on the eastern flank of Pilot Mountain, near the apex of the dacite porphyry stock. Rhyolites of the Uwharrie Formation (delta 18 O = 3.8-6.3ppm) are not as strongly altered as nearby andesites and may postdate the hydrothermal alteration. The fluid calculated to be in equilibrium with the lowest 18 O quartz veins and country rocks at 300 degrees + or - 50 degrees C would have delta 18 O approximately -4.5 + or - 2.0 per mil, whereas analyses of radiating pyrophyllite indicate equilibrium with a fluid having delta D approximately -30 per mil, consistent with a slightly 18 O-shifted, low-latitude meteoric water. Subsequent greenschist metamorphism caused intermineral isotopic reequilibration in several samples and may have modified preexisting alteration assemblages, but it did not destroy the large delta 18 O anomaly produced by meteoric-hydrothermal activity at Pilot Mountain. Reconnaissance studies of other alteration zones in the Carolina slate belt have so far disclosed the involvement of meteoric-hydrothermal fluids at the Snow Camp pyrophyllite deposit, at the Hoover Hill and Sawyer Au mines, and probably at the Haile and Brewer Au mines.

Boggs, Johnny, Ge Sun, David Jones, and Steven G. McNulty, 2012. Effect of Soils on Water Quantity and Quality in Piedmont Forested Headwater Watersheds of North Carolina. Journal of the American Water Resources Association (JAWRA) 1‐19. DOI: 10.1111/jawr.12001Abstract: Water quantity and quality data were compared from six headwater watersheds on two distinct soil formations, Carolina Slate Belt (CSB) and Triassic Basins (TB). CSB soils are generally thicker, less erodible, and contain less clay content than soils found in TB. TB generated significantly more discharge/precipitation ratio than CSB (0.33 vs. 0.24) in the 2009 dormant season. In the 2009 growing season, TB generated significantly less discharge/precipitation ratio than CSB (0.02 vs. 0.07). Over the entire monitoring period, differences in discharge/precipitation ratios between CSB and TB were not significantly different (0.17 vs. 0.20, respectively). Storm‐flow rates were significantly higher in TB than CSB in both dormant and growing season. Benthic macroinvertebrate biotic index scores were excellent for all streams. Nutrient concentrations and exports in CSB and TB were within background levels for forests. Low‐stream nitrate and ammonium concentrations and exports suggested that both CSB and TB were nitrogen limited. Soils appear to have had a significant influence on seasonal and storm‐flow generation, but not on long‐term total water yield and water quality under forested conditions. This study indicated that watersheds on TB soils might be more prone to storm‐flow generation than on CSB soils when converted from forest to urban. Future urban growth in the area should consider differences in baseline hydrology and effects of landuse change on water quantity and quality.

Discovery of oil and gas in the western overthrust belt has spurred renewed efforts in the southwestern and eastern overthrust belts. Reinterpretations of existing data and acquisition of new data, both geologic and geophysical, have led to several interpretations of the sedimentary history and overthrust geometry of these belts. Although the Carolina Slate belt (CSB) is not a prime petroleum exploration target, the documentation of metazoan elements belonging to the late Precambrian Ediacaran fauna in the CSB is new data pertinent to interpretations of sedimentary history and accretion geometry of an exotic terrane that by some interpretations may be involved in overthrusting and is thus concealing potentially petroleum-bearing strata. The presence of Pteridinium in the CSB provides correlation with late Precambrian strata of the Russian platform, South West Africa, and South Australia, and is thus very significant in paleogeographic reconstructions. Pteridinium in the CSB is represented by 4 specimens that are impressions of petal-like metazoans. These metazoans are approximately bilaterally symmetrical, crudely ovoid-shaped, and composed of curved segments that join across a medial zig-zag groove created by the proximal End_Page 479------------------------------ ends of alternating left and right segments. The segments curve toward one end of the organism, terminating distally in spines. Individual segments exhibit longitudinal ornamentation, and grooves separating adjacent segments indicate articulation. Data from the USSR, Africa, and South Australia suggest that Pteridinium lived in a shallow water, near-shore, high-energy environment. However, the CSB examples are preserved in an essentially bedding-parallel position in deep-water flysch, suggesting transportation from nearshore into deep water. End_of_Article - Last_Page 480------------

Research Article| July 01, 1984 Ediacarian fossils from the Carolina slate belt, Stanly County, North Carolina Gail G. Gibson; Gail G. Gibson 1Department of Geography and Earth Sciences, University of North Carolina, Charlotte, North Carolina 28223 Search for other works by this author on: GSW Google Scholar Steven A. Teeter; Steven A. Teeter 1Department of Geography and Earth Sciences, University of North Carolina, Charlotte, North Carolina 28223 Search for other works by this author on: GSW Google Scholar M. A. Fedonkin M. A. Fedonkin 2Paleontological Institute, Academy of Sciences, Profsoyuznaye 113, Moscow B-321, Union of Soviet Socialist Republics 117868 Search for other works by this author on: GSW Google Scholar Author and Article Information Gail G. Gibson 1Department of Geography and Earth Sciences, University of North Carolina, Charlotte, North Carolina 28223 Steven A. Teeter 1Department of Geography and Earth Sciences, University of North Carolina, Charlotte, North Carolina 28223 M. A. Fedonkin 2Paleontological Institute, Academy of Sciences, Profsoyuznaye 113, Moscow B-321, Union of Soviet Socialist Republics 117868 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1984) 12 (7): 387–390. https://doi.org/10.1130/0091-7613(1984)12<387:EFFTCS>2.0.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Gail G. Gibson, Steven A. Teeter, M. A. Fedonkin; Ediacarian fossils from the Carolina slate belt, Stanly County, North Carolina. Geology 1984;; 12 (7): 387–390. doi: https://doi.org/10.1130/0091-7613(1984)12<387:EFFTCS>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Discovery of metazoan fossils, comparable to those of the late Precambrian Ediacarian fauna, in the Carolina slate belt, Stanly County, North Carolina, extends the paleobiogeographic range of the Ediacarian fauna into the southern Piedmont of the southeastern United States. These fossils provide paleontologic correlation with parts of the Precambrian Valdai Series of the Vendian System of the Soviet Union, the Nama Group of South-West Africa, and the Pound Quartzite of South Australia. In light of the recent discoveries, North Carolina fossil material previously described as the Middle Cambrian trilobite ?Paradoxides carolinaensis St. Jean, 1973, was re-examined and identified as an element of the late Precambrian Ediacarian fauna. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Massive sulfide deposits, gold deposits, and tin-bearing minerals occur in rocks of the Carolina slate belt in South Carolina and adjacent Georgia. The belt of greenschist metamorphic rocks in which the ore deposits occur is mostly Cambrian in age. It is divided into an upper metasedimentary unit and a lower unit of predominantly felsic metavolcanic and metavolcaniclastic rocks. The ore deposits occur in the lower unit chiefly near the contact between the two units. The rocks have been deformed into two maior sets of coaxial folds and at least two minor deformations. Coarse-grained unmetamorphosed Carboniferous, I-type granites, and abundant Triassic-Jurassic diabase dikes cut the slate belt and appear largely unrelated to the ore deposits. Remnants of Cretaceous and younger sedimentary rocks overlie the crystalline rocks near several of the larger mineralized areas.Massive sulfides, largely pyrite, and some polymetallic sulfides occur in mines opened for gold in the nineteenth century. The largest of these in South Carolina are the Haile, Brewer, and Dorn mines. These mines and the Little Mountain and Cedar Creek-Blythewood areas have many similar lithologic characteristics. These are: hydrothermally altered wall-rock consisting of quartz-sericite-kaolinite schist and quartz-sericite schist; abundant aluminous silicates such as kyanite, andalusite, pyrophyllite, and topaz; zones of iron-enriched rocks; and a suite of resistant heavy minerals that includes tin-bearing minerals. Heavy mineral concentrates from alluvium of small streams showed 20,000 ppm tin. Cassiterite and nigerite have been identified.At the Brewer mine, gold has been produced from altered felsic volcanic rocks that contain silicified breccia, massive topaz, abundant pyrite, minor enargite, and probably cassiterite. Massive pyrite and gold have been mined at the Haile mine. In the McCormick-Lincolnton area, a near-surface granitoid pluton is thought to be the source for volcaniclastic rocks that contain polymetallic massive sulfide deposits, gold, and associated deposits of kyanite, barite, and manganese. Tin was found there in heavy mineral concentrates, and rutile occurring with kyanite contains 1,000 ppm tin. At Little Mountain, cassiterite and hematite are present in rocks considered to be metamorphosed hot spring deposits. In the Cedar Creek-Blythewood area, nigerite is present, together with cassiterite, chrysoberyl, and seventeen other heavy minerals in concentrates panned from alluvium in streams draining an area of quartz-sericite-kaolinite schist.The deposition of massive sulfides, gold, and tin minerals is considered to be part of a continuum of volcanic activity that included alteration, deformation, and metamorphism. Altered rocks, which host the ore deposits, result from superimposed processes beginning with alteration syngenetic with the massive sulfides and ending with fracture-controlled alteration.

Voids resembling evaporite crystal molds were found in argillites of tile Carolina Slate Belt, North Carolina. If interpreted correctly, they indicate that at least a portion of the Slate Belt was occasionally exposed to the atmosphere before lithification.

Volcanic rocks of the Persimmon Fork Formation host the largest known gold mines of the Carolina slate belt. U-Pb (SHRIMP) zircon ages have been obtained from rocks closely associated with pyrite-enargite-gold deposits at Brewer (quartz-topaz rhyolite breccia from the argillic alteration zone in the Brewer pit and felsic ash-flow tuff from the quartz sericite alteration zone), from the disseminated and semimassive pyrite-gold deposits at Haile (crystal lithic rhyolitic ash-flow tuffs from the Champion pit), and from the Ridgeway deposit (felsic ash-flow tuff from the stratigraphic host of the North pit gold deposit). Generally, the zircons are fine grained, fractured, and contain crystal imperfections (corrosion, inclusions, and pits). 206 Pb/ 238 U zircon spot ages for all deposits span a wide range, mostly from 400 to 760 Ma. Inclusions and cores indicative of inherited domains in the zircons were not found, and only a few analyses range from 1.1 to 1.8 Ga. A distinct xenocrystic zircon population was not identified. The 206 Pb/ 238 U weighted age averages of zircon indicate the following crystallization dates for the volcanic and volcaniclastic rocks closely associated with the gold deposits: 550 ± 3 Ma for Brewer, 553 ± 2 Ma for Haile, and 556 ± 2 Ma for the Ridgeway deposit. These zircon crystallization ages represent close estimates of the age of the original gold mineralizing events. Younger zircon spot ages can be attributed to the effects of Paleozoic regional metamorphism. Pb isotope compositions of sulfide minerals (galena, pyrite, enargite, sphalerite, chalcopyrite, and molybdenite) and silicate minerals (K-feldspar, and sericite) in the gold deposits help to constrain the sources of fluids and metals during the mineralizing events. The deposits are pyrite rich, containing multiple generations of pyrite, including early-crystallized pyrite that is closely associated with the original gold mineralizing event, as well as recrystallized pyrite formed in response to Paleozoic metamorphism. Pb isotope compositions of pyrite span a wide range, including the most radiogenic values for the sulfides. Galena and K-feldspar are not abundant but where present they are typically the least radiogenic minerals. Galena has a limited range of Pb isotope compositions that are representative of the gold deposits as a group ( 206 Pb/ 204 Pb = 18.020–18.326, 207 Pb/ 204 Pb = 15.550–15.639, 208 Pb/ 204 Pb = 37.605–38.286). Values of 207 Pb/ 204 Pb straddle the average crustal Pb growth curve, consistent with contributions involving the mantle and continental crust. Whole-rock Pb isotope compositions of volcanic and volcaniclastic rocks of the Persimmon Fork Formation nearly match the range for sulfides in the gold deposits. Subtle regional contrasts in Pb isotope compositions exist among the deposits. Sulfide minerals from Barite Hill (e.g., galena 206 Pb/ 204 Pb 206 Pb/ 204 Pb > 18.169), Haile ( 206 Pb/ 204 Pb > 18.233), and Brewer ( 206 Pb/ 204 Pb > 18.311) in northern South Carolina. Because Pb isotope compositions of basement rocks from Grenville massifs in the southern Appalachians and sulfide minerals from the gold deposits do not match, a direct genetic connection cannot be established. Diversity in values of 206 Pb/ 204 Pb and the relatively high values of 207 Pb/ 204 Pb suggest that the deposits evolved adjacent to or closely related to continental blocks, perhaps linked to a back-arc tectonic setting. Among potential younger analogues of the slate belt gold deposits are the sulfide deposits of the Okinawa trough in the western Pacific. Mantle-derived isotopic contributions were more important at Barite Hill in southern South Carolina, the least radiogenic among the deposits where oceanic crust had developed, than at Brewer, Haile, and Ridgeway in northern South Carolina where rifting thinned the continental crust.

The central part of the Carolina terrane in western South Carolina comprises a 30 to 40 km wide zone of high grade gneisses that are distinct from greenschist facies metavolcanic rocks of the Carolina slate belt (to the SE) and amphibolite facies metavolcanic and metaplutonic rocks of the Charlotte belt (to the NW). This region, termed the Silverstreet domain, is characterized by penetratively deformed felsic gneisses, granitic gneisses, and amphibolites. Mineral assemblages and textures suggest that these rocks formed under high‐pressure metamorphic conditions, ranging from eclogite facies through high‐P granulite to upper amphibolite facies.Mafic rocks occur as amphibolite dykes, as metre‐scale blocks of coarse‐grained garnet‐clinopyroxene amphibolite in felsic gneiss, and as residual boulders in deeply weathered felsic gneiss. Inferred omphacite has been replaced by a vermicular symplectite of sodic plagioclase in diopside, consistent with decompression at moderate to high temperatures and a change from eclogite to granulite facies conditions. All samples have been partially or wholly retrograded to amphibolite assemblages. We infer the following P‐T‐t history: (1) eclogite facies P‐T conditions at ≥ 1.4 GPa, 650–730 °C (2) high‐P granulite facies P‐T conditions at 1.2–1.5 GPa, 700–800 °C (3) retrograde amphibolite facies P‐T conditions at 0.9–1.2 GPa and 720–660 °C. This metamorphic evolution must predate intrusion of the 415 Ma Newberry granite and must postdate formation of the Charlotte belt and Slate belt arcs (620 to 550 Ma).Comparison with other medium temperature eclogites and high pressure granulites suggests that these assemblages are most likely to form during collisional orogenesis. Eclogite and high‐P granulite facies metamorphism in the Silverstreet domain may coincide with a ≈570–535 Ma event documented in the western Charlotte belt or to a late Ordovician‐early Silurian event. The occurrence of these high‐P assemblages within the Carolina terrane implies that, prior to this event, the western Carolina terrane (Charlotte belt) and the eastern Carolina terrane (Carolina Slate belt) formed separate terranes. The collisional event represented by these high‐pressure assemblages implies amalgamation of these formerly separate terranes into a single composite terrane prior to its accretion to Laurentia.

Paleomagnetic samples of two late Paleozoic plutons were collected from the eastern Piedmont Province in North Carolina. Results from the early Carboniferous (326±27 m.y.) Lilesville pluton, located in the Carolina Slate Belt, indicate a pole position similar to that of the stable North American craton for the lower Carboniferous. Five sites inthis gabbro/granite complex give a pole of 40°N, 134°E (α 95 = 2.9). The late Carboniferous 282±6 m.y.) Churchland pluton, located in the Charlotte Belt, gives a pole of 34°N, 126°E α 95 = 16.3) which correlates well with other North American poles for the late Carboniferous. Observations made by Kent and Opdyke (1978) on rocks from the eastern edge of the northern Appalachians suggest gross lateral displacement between the mid‐Devonian and late Carboniferous in the late Paleozoic. This paleomagnetic information from the eastern Piedmont region implies that the area of the Carolina Slate Belt and Charlotte Belt was associated with the North American platform for the entire Carboniferous period. The Slate Belt rocks, although geologically a southern counterpart to some of the Avalonian rocks from the northeastern edge of North America, do not display a paleomagnetic history suggestive of great displacement.

Research Article| August 01, 1971 Nappe Formation in Part of the Southern Appalachian Piedmont OTHMAR T TOBISCH; OTHMAR T TOBISCH Division of Natural Sciences, University of California, Santa Cruz, California 95060 Search for other works by this author on: GSW Google Scholar LYNN GLOVER, III LYNN GLOVER, III Department of Geology, Virginia Polytechnic Institute, Blacksburg, Virginia 24060 Search for other works by this author on: GSW Google Scholar Author and Article Information OTHMAR T TOBISCH Division of Natural Sciences, University of California, Santa Cruz, California 95060 LYNN GLOVER, III Department of Geology, Virginia Polytechnic Institute, Blacksburg, Virginia 24060 Publisher: Geological Society of America Received: 06 Nov 1970 Revision Received: 09 Mar 1971 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Copyright © 1971, The Geological Society of America, Inc. Copyright is not claimed on any material prepared by U.S. government employees within the scope of their employment. GSA Bulletin (1971) 82 (8): 2209–2230. https://doi.org/10.1130/0016-7606(1971)82[2209:NFIPOT]2.0.CO;2 Article history Received: 06 Nov 1970 Revision Received: 09 Mar 1971 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation OTHMAR T TOBISCH, LYNN GLOVER; Nappe Formation in Part of the Southern Appalachian Piedmont. GSA Bulletin 1971;; 82 (8): 2209–2230. doi: https://doi.org/10.1130/0016-7606(1971)82[2209:NFIPOT]2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Structural studies of rocks along the Carolina slate belt – Charlotte belt boundary reveal two generations of folding, the earlier of which is represented by a large-scale antiformal nappe. As shown by field relations and quantitative analysis of the fold geometry, this early folding began prior to metamorphism, the mechanism being largely buckling. With the onset of metamorphism and cleavage-forming process, new folds were formed and the pre-existing buckle folds were modified by compressive strain. During this time, a metamorphic gradient developed along the boundary of the two belts; as the rocks became more ductile, the large antiformal nappe was emplaced in the Charlotte belt, with its root located close to the boundary between the belts. Sillimanite-grade metamorphism in the Charlotte belt outlasted the early deformation, and some upwelling of material in this hot zone may have gently arched the nappe. Late, post-metamorphism deformation produced two sets of folds with different orientation, which appear to have a conjugate relationship, and which probably formed contemporaneously.The relation between the Charlotte and Carolina slate belts may be analogous to the infrastructure/superstructure relation commonly found in other intensely deformed mountain belts of the world. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.