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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

FIELD, GEOCHRONOLOGIC, AND GEOCHEMICAL CONSTRAINTS ON LATE PRECAMBRIAN TO EARLY PALEOZOIC TERRANE ACCRETION IN THE SOUTHERN APPALACHIAN BLUE RIDGE PROVINCE

Larkin, Emma A. 01 January 2016 (has links)
Xenolith-bearing orthogneiss of Amazonian affinity discovered in the Dellwood quadrangle in the Blue Ridge basement complex represents the oldest crustal component of the southern Appalachians (1.33 – 1.37 Ga: Quinn, 2012). New U-Pb zircon ages for migmatitic paragneiss of the Cartoogechaye terrane exposed in the Dellwood quadrangle reveal two unique detrital zircon age signatures that indicate either a local eastern Laurentian margin source or an exotic source. Detailed mapping, whole rock geochemistry, and U-Pb zircon geochronology were conducted to determine whether this exotic crustal component extends farther south into the Hazelwood 7.5” quadrangle. Lithological similarities exist between paragneisses in the Dellwood quadrangle and those in the Hazelwood quadrangle. However, the increase in proportion of leucosome and polyphase folding prevent direct correlation of lithologies between the areas. Whole rock major element compositions overlap the composition of basement orthogneisses. Zircon ages of six paragneiss samples reveal multiple detrital zircon age modes that are dominated by two Grenville modes at ~1050 and 1150 Ma. Minor zircon populations exist at ~450 – 480, 700 – 900, and 1300 – 1500 Ma. Age distributions and compositional trends are evidence that the protolith of the paragneiss in the Hazelwood quadrangle was Neoproterozoic rift sediments with a dominant Laurentian margin source.

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