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

Abstract

Research Article| July 01, 1976 Age and origin of the Stone Mountain Granite, Lithonia district, Georgia JAMES A. WHITNEY; JAMES A. WHITNEY 1Department of Geology, University of Georgia, Athens, Georgia 30602 Search for other works by this author on: GSW Google Scholar LOIS M. JONES; LOIS M. JONES 1Department of Geology, University of Georgia, Athens, Georgia 30602 Search for other works by this author on: GSW Google Scholar RAYMOND L. WALKER RAYMOND L. WALKER 2Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830 Search for other works by this author on: GSW Google Scholar Author and Article Information JAMES A. WHITNEY 1Department of Geology, University of Georgia, Athens, Georgia 30602 LOIS M. JONES 1Department of Geology, University of Georgia, Athens, Georgia 30602 RAYMOND L. WALKER 2Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1976) 87 (7): 1067–1077. https://doi.org/10.1130/0016-7606(1976)87<1067:AAOOTS>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 JAMES A. WHITNEY, LOIS M. JONES, RAYMOND L. WALKER; Age and origin of the Stone Mountain Granite, Lithonia district, Georgia. GSA Bulletin 1976;; 87 (7): 1067–1077. doi: https://doi.org/10.1130/0016-7606(1976)87<1067:AAOOTS>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 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. 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.