Geologic map of the Atlanta 30' x 60' quadrangle, Georgia

Higgins, Michael W.; Crawford, Thomas J.; Atkins, Ruth; Crawford, R.F.

doi:10.3133/ofr98245

Cited by 7 publications

(15 citation statements)

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“…One of the four granites we studied most intensively, from Panola, GA (A4 , Table 1), contained up to 3.32 g kg Ϫ1 calcite. This Carboniferous granite is located within a region of Ordovician gneisses and other high-grade metamorphic rocks, but not carbonates (Higgins et al, 1998). In the Panola granite, calcite is typically associated with biotite (Fig.…”

Section: Petrogenesis Of Calcitementioning

confidence: 99%

The ubiquitous nature of accessory calcite in granitoid rocks: Implications for weathering, solute evolution, and petrogenesis

White¹,

Schulz²,

Lowenstern³

et al. 2005

Geochimica et Cosmochimica Acta

138

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Section: Petrogenesis Of Calcitementioning

confidence: 99%

The ubiquitous nature of accessory calcite in granitoid rocks: Implications for weathering, solute evolution, and petrogenesis

White¹,

Schulz²,

Lowenstern³

et al. 2005

Geochimica et Cosmochimica Acta

138

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“…On the basis of the above evidence, we interpret the Bill Arp Formation and Gothards Creek Gneiss to be older than the Austell Gneiss. The fault(s) that emplaced the allochthonous assemblage upon the parautochthonous assemblage has been cut and displaced by the faults that have sliced up the Austell Gneiss west of Douglasville, so it must be as old as, or more likely older than, the Early Silurian Austell Gneiss, an age that fits well with the time of slope reversal in the Valley and Ridge province nearby (Higgins et al, 1997). Because the contact of the Gothards Creek Gneiss with the allochthonous assemblage is everywhere a fault contact and the Gothards Creek is also in fault contact with rocks of the parautochthonous assemblage, it is unknown whether it belongs to the allochthonous or parautochthonous assemblage.…”

Section: Austell Gneissmentioning

confidence: 78%

“…Crawford and Medlin (1974, p. 2) also recognized that the Piedmont-Blue Ridge in western Georgia is made up of two assemblages of rocks that Higgins et al (1997) called the parautochthonous continental margin assemblage, genetically linked to Grenville basement, and the allochthonous oceanic assemblage (Fig. 1), made up of rocks formed in an ancient ocean that probably lay offshore from the continental margin of the parautochthonous assemblage.…”

Section: Geologic Settingmentioning

confidence: 99%

“…The allochthonous assemblage is interpreted to have been obducted onto the parautochthonous assemblage, probably in Middle Ordovician through Late Ordovician time, on the basis of the time of slope reversal in the Valley and Ridge province (Higgins et al, 1997), shown by deposition of dark pelites (Rockmart Slate, Athens Shale) on a subsiding shelf. The folded thrusts were in turn displaced in a dextral wrench-fault system similar to the San Andreas system in California (Crowell, 1962(Crowell, , 1974Dibblee, 1977) and other wrench-fault systems (e.g., Wilcox et al, 1973).…”

Section: Geologic Settingmentioning

confidence: 99%

“…In addition to occupying the same structural position as the Middle(?) to Late Proterozoic Corbin Metagranite basement (Higgins et al, 1997;Fig. 1) in the Mulberry Rock structure, the Austell Gneiss occupies the same structural position as the thrust fault that brought the allochthonous assemblage over the parautochthonous assemblage (Figs.…”

Section: Austell Gneissmentioning

confidence: 99%

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Age and origin of the Austell Gneiss, western Georgia Piedmont-Blue Ridge, and its bearing on the ages of orogenic events in the Southern Appalachians

Higgins¹,

Arth²,

Wooden³

et al. 1997

The Nature of Magmatism in the Appalachian Orogen

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The Austell Gneiss is a metamorphosed biotite granite in the northeastern closure of the Austell-Frolona anticlinorium, a major northeast-trending early fold on the northwestern side of the Brevard fault zone. The anticlinorium is a structural window that exposes rocks of a parautochthonous continental-margin assemblage beneath rocks of an allochthonous oceanic assemblage. The Austell Gneiss and the Austell-Frolona anticlinorium were deformed by younger en echelon folds during dextral wrench faulting along the Brevard and Olley Creek fault zones. The Austell Gneiss has intruded the Bill Arp Formation and the Gothards Creek Gneiss, but is in fault contact with other units.The Austell Gneiss has yielded Pb-U ages on older zircon fractions and a six point Rb-Sr whole-rock isochron that are interpreted to indicate a crystallization age as a granite of about 430 Ma (Early Silurian). A still older zircon fraction is interpreted to be inherited from ~1.1 Ga basement. Younger zircon fractions yield ages interpreted to indicate synmetamorphic deformation during strike-slip and thrust faulting throughout the Silurian and Early Devonian. The Early Silurian crystallization age of the Austell indicates (1) that the thrusting that placed the allochthonous assemblage upon the parautochthonous assemblage took place prior to Early Silurian; we postulate that it took place during the Middle Ordovician, the time of slope reversal in the Valley and Ridge province. All rocks involved in that thrusting must be older than Early Silurian.(2) The early folding that produced the Austell-Frolona anticlinorium and folded the Austell Gneiss took place during and/or after the Early Silurian. (3) Most of the dextral wrench and strike-slip faulting and wrench folding along the Brevard and Olley

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Quantifying Climate‐Related Interactions in Shallow and Deep Storage and Evapotranspiration in a Forested, Seasonally Water‐Limited Watershed in the Southeastern United States

Aulenbach

Peters

2018

Water Resources Research

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The Southeastern United States experiences recurring hydrological droughts, which can reduce water availability and result in water deficits. Long‐term monitoring data from Panola Mountain Research Watershed, a small, forested, seasonally water‐limited watershed near Atlanta, GA, was used to quantify interactions of climatic variability with shallow and deep storage and evapotranspiration. Watershed storage (WS) and actual evapotranspiration (AET) were estimated monthly from 1985 through 2015 using a relationship with baseflow and a water‐budget approach, respectively. A watershed shallow storage (SS) water budget, based on soil moisture profile data, indicated a transition from recharge to surplus as dormant season SS increased to field capacity, and a transition from utilization of stored water to water deficits as growing season SS declined toward its wilting point. Deeper storage appeared unavailable to AET during dry conditions. The majority of deeper storage recharge occurred during the dormant season and required SS to be near field capacity. WS was an effective drought indicator. Growing season droughts typically occurred when WS was below normal at the end of the dormant season and growing season precipitation (P) was below or near normal. A hydrologic persistence analysis showed that monthly month‐standardized WS was significantly correlated (p‐value < 0.05) with past monthly month‐standardized WS for the previous 19 months and with past monthly P for the previous 11 months, indicating the importance of past hydrologic conditions on WS. These findings allowed assessment of expected climatic changes on the water cycle, which included effects on future recharge, water deficits, and drought occurrence.

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Geologic map of the Atlanta 30' x 60' quadrangle, Georgia

Cited by 7 publications

References 0 publications

The ubiquitous nature of accessory calcite in granitoid rocks: Implications for weathering, solute evolution, and petrogenesis

The ubiquitous nature of accessory calcite in granitoid rocks: Implications for weathering, solute evolution, and petrogenesis

Age and origin of the Austell Gneiss, western Georgia Piedmont-Blue Ridge, and its bearing on the ages of orogenic events in the Southern Appalachians

Quantifying Climate‐Related Interactions in Shallow and Deep Storage and Evapotranspiration in a Forested, Seasonally Water‐Limited Watershed in the Southeastern United States

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