Talladega ‘Series,’ Great Smoky fault, and Emerson fault: Relationships in the Cartersville area, Georgia

Crawford, Thomas J.; Cressler, Charles W.

doi:10.1130/spe191-p31

Cited by 6 publications

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“…MORB and tholeiitic within-plate ba-B p E-type salts (WPB); WPB; plate C p alkaline D p destructive margin basalts (calc-alkaline); plate mar-E p destructive gin basalts (primitive arc tholeiite). cated by pervasive imbricate faulting (Crawford and Cressler 1982;Holm and Farmer 2002) and has been variously equated with the Hollins line fault (Heuler 1993) or the Goodwater-Enitachopco fault (Bentley and Neathery 1970;Hatcher et al 1990), although the latter fault was interpreted as a normal fault that cuts the Hollins line thrust . If the Hillabee-Dahlonega correlation is correct, however, the Allatoona fault and the Hillabee shear zone may represent essentially the same structural level, although perhaps as parts of a broader zone rather than as one discrete fault.…”

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confidence: 99%

Isotopic Age Constraints and Metamorphic History of the Talladega Belt: New Evidence for Timing of Arc Magmatism and Terrane Emplacement along the Southern Laurentian Margin

McClellan¹,

Steltenpohl²,

Thomas³

et al. 2007

The Journal of Geology

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Talladega belt, southernmost Appalachians, provide insight into the timing and nature of pre-Alleghanian tectonism in this region. Low-grade metasedimentary rocks of the Talladega belt represent the outermost preserved portions of the southern Laurentian margin, thus recording the earliest orogenic events that affected the margin, in addition to later overprinting events. These rocks are structurally overlain by the Hillabee Greenstone metavolcanic sequence, from which metadacite yields an age of ‫4ע074‬ Ma (ion microprobe U-Pb zircon age). Hillabee geochemistry indicates formation in an arc or back-arc setting. We suggest correlation of the Hillabee Greenstone with 460-470-Ma arc-related rocks in the Dahlonega gold belt, which extends along strike with the Hillabee through Georgia and into North Carolina, and interpret the Hillabee as the southernmost volcanic expression of an Early-Middle Ordovician arc that formed outboard of Laurentia. Rocks of the Talladega belt, including the Hillabee, preserve a record of only one Paleozoic dynamothermal metamorphic event. 40 Ar/ 39 Ar dates are consistent with metamorphism following deposition of the youngest biostratigraphically dated unit, the Erin Slate, which contains early Mississippian Periastron plant fossils (360-350 Ma). Muscovite (closure temperature 350Њ-400ЊC) yields internally consistent ages between 334 and 320 Ma. Metamorphism of the Talladega belt, therefore, is constrained to the interval between 360 and 320 Ma. The pre-to synmetamorphic thrust contact between the Hillabee Greenstone and Talladega belt metasedimentary rocks must have formed after deposition of the Erin Slate at 360-350 Ma but before metamorphism of the Talladega belt (no later than ∼320 Ma). We propose that the Ordovician Hillabee-Dahlonega arc terrane first collided with the Laurentian continental margin between 360 and 320 Ma, with variations in timing of deformation and metamorphic character along the collision zone.

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confidence: 99%

Isotopic Age Constraints and Metamorphic History of the Talladega Belt: New Evidence for Timing of Arc Magmatism and Terrane Emplacement along the Southern Laurentian Margin

McClellan¹,

Steltenpohl²,

Thomas³

et al. 2007

The Journal of Geology

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“…Farther northeast into Georgia most geologic maps depict the fault to be the Allatoona fault (Hurst, 1973;Tull, 1978;Hatcher et al, 1990;Tull and Holm, 2005). The Goodwater-Enitachopco/Allatoona fault has been interpreted as a southeast-dipping reverse (thrust) fault (Neathery and Tull, 1975;Pickering, 1976;Tull, 1978Tull, , 1984Costello, 1980, 1982;Crawford and Cressler, 1982;McConnell and Abrams, 1984;Osborne et al, 1988;McClellan et al, 2005;Tull and Holm, 2005). , on the other hand, interpreted the Goodwater-Enitachopco to be a normal fault, reasoning that a thrust fault cutting the basal eastern Blue Ridge thrust (i.e., the Hollins line) should emplace Talladega slate belt rocks in the hanging wall.…”

Section: Discussion and Directions For Future Studiesmentioning

confidence: 97%

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et al. 2013

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We dedicate this paper to the memory of coauthor Isidore (Izzy) Zietz, who died at age 93 while this paper was in review. After contributing to the early theoretical foundation for analysis of airborne magnetic surveys, Izzy became a leading advocate for aeromagnetic survey acquisition and interpretation throughout the U.S., combining surveys into regional, state, and national maps, and working with regional geologists in interpreting geophysical anomalies. Like many geologists, we have been energized by Izzy's contagious enthusiasm for using magnetic and gravity anomalies to delineate and characterize major tectonic features. Lessons from working with him on data from Alabama and elsewhere over the years will continue to infl uence our appreciation and understanding of aeromagnetic and gravity anomalies for interpreting the Earth's upper crust."Magnetics is never good, and gravity is even worse!" "…all of it can just be dashed." -Isidore Zietz ABSTRACT Aeromagnetic and gravity data sets obtained for Alabama (United States) have been digitally merged and fi ltered to enhance upper-crustal anomalies. Beneath the Appalachian Basin in northwestern Alabama, broad deep-crustal anomalies of the continental interior include the Grenville front and New York-Alabama lineament (dextral fault). Toward the east and south, high-angle discordance between the northeast-trending Appalachians and the east-west-trending wedge of overlapping Mesozoic and Cenozoic Gulf Coastal Plain sediments reveals how bedrock geophysical signatures progressively change with deeper burial. Highfrequency magnetic anomalies in the Appalachian deformed domain (ADD) correspond to amphibolites and mylonites outlining terranes, while broader, lower-amplitude domains include Paleozoic intrusive bodies and Grenville basement gneiss. Fundamental ADD structures (e.g., the Alexander City, Towaliga, and Goat Rock-Bartletts Ferry faults) can be traced southward beneath the Gulf Coastal Plain to the suture with Gondwanan crust of the Suwannee terrane. Within the ADD, there is clear magnetic distinction between Laurentian crust and the strongly linear, high-frequency magnetic highs of peri-Gondwanan (Carolina-Uchee) arc terranes. The contact (Central Piedmont suture) corresponds to surface exposures of the Bartletts Ferry fault. ADD magnetic and gravity signatures are truncated by the eastwest-trending Altamaha magnetic low associated with the Suwannee suture. Arcuate northeast-trending magnetic linears of the Suwannee terrane refl ect internal structure and Mesozoic failed-rift trends. Geophysical data can be used to make inferences on surface and subsurface geology and vice versa, which has applicability anywhere that bedrock is exposed or concealed beneath essentially non-magnetic sedimentary cover.

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“…3-6) are found west of a major thrust fault that forms the west border of the southwestern part of the Dahlonega gold belt. Southwest of Bartow County, these low-grade rocks are part of the Talledaga Group of Alabama (German, 1988); northeast of Bartow County similar, but higher grade metasedimentary rocks are correlated with rocks of the Ocoee Supergroup in the Great Smoky thrust sheet (Crawford and Cressler, 1982;McConnell and Costello, 1982). Only 3 samples out of 51 collected from these rocks (A14, DL5, and DL6, fig.…”

Section: Phyllite Slate and Metasandstonementioning

confidence: 99%

Geochemical reconnaissance of the Carroll County Gold Belt and southwestern part of the Dahlonega Gold Belt, western Georgia

Lesure¹

1993

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The gold deposits in the Carroll County gold belt and the southwestern part of the Dahlonega gold belt are in interlayered metasedimentary and metavolcanic rocks of Late Proterozoic to early Paleozoic age. These rocks are in several thrust sheets that form the southwest continuation of the Blue Ridge thrust stack. The rocks are now mostly mica gneiss and schist, graphitic schist and phyllite, quartzite, amphibolite, and granite gneiss. A sample suite of 788 rock and saprolite samples was collected; the suite represents most of the rock types exposed in the southwest extension of the Dahlonega gold belt in Cherokee, Cobb, Bartow, Paulding, and Haralson Counties, Ga., and in the Carroll County gold belt in Carroll and Douglas Counties, Ga. The samples were analyzed semiquantitatively for 30 elements and quantitatively for gold, copper, lead, and zinc; some samples were also analyzed quantitatively for arsenic, mercury, and molybdenum. Whole-rock analyses were made on 27 samples of relatively fresh mafic rock. More than two-thirds of the samples are saprolite derived from mica schist and gneiss, graphitic schist, amphibolite, and quartzite, or vein quartz in saprolite. The samples were collected from roadcuts, surface and underground mine workings, and mine dumps. Of the samples collected, 78 percent of those from old mine areas and 13 percent of those from roadcuts contain gold at or above a limit of determination of 0.02 parts per million (ppm). Of those samples that contain detectable gold, 36 percent of the mine samples and 92 percent of the roadcut samples have less than 0.2 ppm gold. Gold is present in detectable amounts in some samples from all the major rock types that were sampled. Gold does not correlate consistently with the other elements in the data set. The few positive correlation coefficients greater than 0.50 are restricted to the smaller subsets of a few samples. Most of the old mine areas contain small resources of .gold in saprolite and probably larger amounts of lower grade material in unweathered rock. The mineralized zones are generally about 5 to 100ft wide, but may be as much as 250ft wide. Many deposits are only 100 to 800ft long, but a few mineralized zones are longer; one is as much as 0. 75 mi long.

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Talladega ‘Series,’ Great Smoky fault, and Emerson fault: Relationships in the Cartersville area, Georgia

Cited by 6 publications

References 0 publications

Isotopic Age Constraints and Metamorphic History of the Talladega Belt: New Evidence for Timing of Arc Magmatism and Terrane Emplacement along the Southern Laurentian Margin

Isotopic Age Constraints and Metamorphic History of the Talladega Belt: New Evidence for Timing of Arc Magmatism and Terrane Emplacement along the Southern Laurentian Margin

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Geochemical reconnaissance of the Carroll County Gold Belt and southwestern part of the Dahlonega Gold Belt, western Georgia

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