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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

PROVENANCE OF THE NEOPROTEROZOIC OCOEE SUPERGROUP, EASTERN GREAT SMOKY MOUNTAINS

Chakraborty, Suvankar 01 January 2010 (has links)
The Ocoee Supergroup is a sequence of Neoproterozoic, immature, continental rift facies clastic sediments. Potential source rocks were tested by analyzing modes of detrital framework minerals, detrital mineral chemistry, whole rock geochemistry and detrital zircon U/Pb geochronology by LA-ICP-MS for Ocoee siltstone-sandstone dominated formations. Ocoee units are arkosic to subarkosic siltstones/sandstones, and ternary tectonic discrimination diagrams confirm a continental basement uplift source. Alkali feldspar predominates over plagioclase feldspar. Detrital feldspar compositions of Ocoee sediments as a group are similar to feldspar in local basement granitic rocks except for high-Ca plagioclase grains present locally in basement granitic rocks. The high alkali content of the detrital feldspars in the Ocoee Supergroup is consistent with derivation from an A-type granite source terrane. Normative Q-A-P values, calculated from wholerock chemistry, and trace element diagrams are also supportive of an A-type granite source for these rocks. The siltstones and sandstones of the Snowbird Group contain high abundances of heavy minerals (zircon, titanite, ilmenite, epidote and apatite), which are dispersed among other detrital grains and as concentrations of heavy minerals in discrete laminae. ZTR index and titanite mineral chemistry suggest a granitic source for these sediments. Detrital zircon geochronology in Ocoee sediments indicates a dominantly Grenville (1000 to 1300 Ma) source for these sediments. The youngest zircon age in the basal Ocoee Wading Branch Formation (639±8 Ma) is related to rift magmatism and provides a minimum depositional age for the Ocoee Supergroup.

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