Ar/ Ar Ages of Feldspar and Muscovite from the Source and Detritus of The
40Ar/39Ar Ages of Feldspar and Muscovite from the Source and Detritus of the French Broad River, North Carolina by Di Fan A thesis submitted to the Graduate Faculty of Auburn University in partial fulfillment of the requirements for the Degree of Master of Science Auburn, Alabama August 6th, 2016 Keywords: muscovite, K-feldspar, 40Ar/39Ar, geochronology, Blue Ridge, French Broad River Copyright 2016 by Di Fan Approved by Willis E. Hames, Chair, Professor of Geosciences Mark G. Steltenpohl, Professor of Geosciences Haibo Zou, Associate Professor of Geosciences Abstract As the westernmost metamorphic belt of the Appalachians, the Blue Ridge has been the subject of many geochronology studies. The Blue Ridge experienced high-grade deformation and peak metamorphism during Taconic orogeny, followed by a low-grade metamorphic overprint during the Acadian orogeny. The Alleghanian orogeny is the last collisional stage of the Appalachians and associated regional metamorphism and ductile deformation is documented along most of the Piedmont and the Carolina Slate belt. There is still debate, however, as to the extent of Alleghanian metamorphism in the western Blue Ridge. This concern is made more difficult to evaluate because previous work generally did not characterize the history of low-temperature metamorphism of the Blue Ridge in the region between western North Carolina and Tennessee. To address the cooling history of the Blue Ridge, samples were collected in the area of the French Broad River catchment in North Carolina. Single crystals of muscovite from basement and stream sediment samples and K-feldspar from the basement, were dated in this project to avoid the ‘inherited’ ages often associated with high-temperature geochronometers.
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