Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by WHITNEY, J. A. Articles by WALKER, R. L. Search for Related Content GeoRef GeoRef Citation

Age and origin of the Stone Mountain Granite, Lithonia district, Georgia

¹ Department of Geology, University of Georgia, Athens, Georgia 30602
² Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830

Petrographic, geochemical, and strontium isotopic studies have been conducted on samples of the Stone Mountain Granite (leucocratic quartz monzonite) from the Lithonia district, within the Inner Piedmont province of Georgia. A Rb-Sr isochron obtained from 10 whole-rock and 3 mineral samples yielded an age of 291 ± 7 m.y. and an initial Sr⁸⁷Sr⁸⁶ ratio of 0.7250 ± 0.0005. Petrologic and geochemical data, combined with the high initial strontium isotopic ratio, suggest that the origin of this peraluminous quartz monzonite can best be explained by the anatexis of an older peraluminous, granitic crustal material during Late Pennsylvanian time. The depth of intrusion was probably around 12 km, with initial magma temperatures of 700°C or less. Magma generation could have occurred at depths of 22 to 28 km, depending on the regional geothermal gradient at the time. The most likely source material is the Lithonia Gneiss, which has a peraluminous, granitic composition and underlies the area.

The Stone Mountain pluton extends the 300-m.y.-old intrusive belt in the southern Appalachians across the Piedmont province to just south of the Brevard lineament. Its implied depth of intrusion fits well with certain models for the development of the Inner Piedmont and Blue Ridge provinces in the Carolinas because it requires rapid removal of considerable overburden. The origin and magmatic history of this intrusive unit may find use as a model for other peraluminous granitic plutons having similar petrologic, geochemical, and isotopic characteristics.

Key Words: igneous rocks • granite • petrology • geochemistry • geochronology • southern Appalachians • Georgia

This article has been cited by other articles:

				N. B. W. Harris, H. J. Duyverman, and D. C. Almond The trace element and isotope geochemistry of the Sabaloka Igneous Complex, Sudan Journal of the Geological Society, April 1, 1983; 140(2): 245 - 256. [Abstract] [PDF]