2007 GSA Denver Annual Meeting (28–31 October 2007)

Paper No. 71
Presentation Time: 8:00 AM-12:00 PM


PRASSE, Andrew B. and RAHL, Jeffrey M., Department of Geology, Washington and Lee University, Lexington, VA 24450, prassea@wlu.edu

Our ongoing research involves assembling geochronological and thermochronological data from the Appalachian Mountain belt and placing this information into a GIS (Geographic Information System) database. The data are plotted and analyzed using the GIS program ArcMap to relate the geographic location of each sample to its corresponding radiometric dating method and age. The point data is overlain on a geologic map of the Appalachian belt. Trends in crystallization ages of igneous and metamorphic rocks mark areas of orogenic activity, and thermochronological data constrain regional exhumation rates. Crystallization ages are found primarily in igneous geologic units along the core of the mountain belt in the Blue Ridge and Valley and Ridge Provinces. The thermochronological data are concentrated in the metamorphic and sedimentary units in the Appalachain Plateau. Cumulative distribution plots of the data for the various geochronologic systems reveal pulses that correspond to the Taconic, Acadian, and Alleghanian orogenic episodes. Detailed analysis for many regions is limited due to the lack of data; however, local areas of high data density allows for age contouring to reveal regional trends in crystallization and cooling across the Appalachians. As more data are collected and incorporated, the database will provide a powerful tool to study the orogenic and exhumational history of the Appalachian mountain belt.