Collaborative Research: Isotopic, Geochronologic, and Tectonic Character of the Western Piedmont, Virginia - Implications for the Closing of Iapetus

Texas A&M Research Foundation, College Station TX

Investigators

Abstract

The Iapetus Ocean is a first-order early Paleozoic oceanic tract that separated eastern North America from peri-Gondwanan crustal blocks. Its closure, which juxtaposed North America with these Gond¬wan¬an elements in the Appalachians, imposed new circulation regimes upon the global hydrosphere and atmosphere and it was a major step toward the eventual amal¬gamation of the supercontinent of Pangea. Despite the importance of Iapetus in the global evolution of the Paleozoic, little is known about the timing and nature of its closure, mainly because the original interface between North American and Gondwanan elements, the main Iapetan suture, is unrecognized in the U.S. Appalachians. On the basis of regional geological relationships and scant isotopic data, it is hypothesized that the Chopawamsic fault in central Virginia represents the main Iapetan suture in the US Appalachians. This project is testing this hypothesis by inte¬grating the results of Nd- and Pb- isotopic studies of magmatic rocks on either side of the fault; by a U-Pb zircon geochron¬ologic study of detrital zircon populations from either side of, and in strata lying above, the fault; by using high resolution U-Pb geochronology on selected magmatic units, and by a kinematic and geochronologic analysis of the fault. This study is a collaborative effort between researchers at North Carolina State University and Texas A&M University. Appalachian geology governs resources (mineral, water) for, and influences the wellbeing (seismic hazards) of, the densest human population in North America; logically, a basic understanding of the bedrock geology is essential to further development and sustainability in the region. Results of this study will also take multiple paths into the broader domains of education and outreach. The project partially supports eight students, including two females. The principal investigators are actively recruiting incoming freshman from urban high schools and from minority groups to work on this project. Texas A&M students involved in the project are encouraged to volunteer and participate in established outreach functions with the Brazos Valley Museum of Natural History. Graduate students intend to present their findings at both professional meetings and at meetings of the Virginia Association of Science Teachers, and disseminate results through the Virginia Science Standards Institute. Once significant results are available, project personnel will lead the Virginia Field Conference, an annual field trip that caters to a broad array of participants. In addition, the involvement of Canadian collaborators and a South African MS candidate adds an international component to the project. Scientific results that derive from the project will be disseminated via presentations at professional geoscience meetings and the peer-reviewed scientific literature.