Masters Thesis

Detrital Zircon Uranium-lead Geochronology of the Schoonover Sequence (golconda Allochthon) and the Yokuts Pendants (western Sierra Nevada Mountains): Insights Into the Late Paleozoic Evolution of Western Laurentia

Detrital zircon U-Pb geochronology provides a statistical basis for identifying provenance and correlating deformed volcanosedimentary rocks. Uranium-lead (U-Pb) detrital zircon ages from the Schoonover Sequence of the Golconda allochthon (GA) are compared with select metasedimentary pendants in the western Sierra Nevada foothills with the goal of providing new constraints for reconstructing the Paleozoic-Mesozoic tectonic evolution of western Laurentia. Comparison of U-Pb data with known basement rocks and other sedimentary units of Laurentia reveal the provenance of the Schoonover Sequence to be a combination of Peace River Arch (PRA) detritus mixed with 349 ± 2.0 Ma zircon likely derived from the Yukon-Tanana arcs (SE Alaska). These new data for the Golconda allochthon reveal the southward translation of the strata to approximately NW Nevada where the strata were thrust over the outermost edge of the passive margin. Two Sierra foothills pendants from the newly named Yokuts series have a provenance similar to the RMA mixed with zircon derived from the post-mid-Cambrian passive margin. Protoliths of the Yokuts pendants deposited near the RMA-GA collision zone within in the passive margin. Subsequent southward translation deformed and juxtaposed the Yokuts strata against undeformed passive margin strata preserved in the neighboring Slate Mountain and Sequoia pendants.


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