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Geology

Central Washington University

Geochronology

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Full-Text Articles in Physical Sciences and Mathematics

High Throughput Petrochronology And Sedimentary Provenance Analysis By Automated Phase Mapping And Laicpms, Pieter Vermeesch, Martin Rittner, Ethan Petrou, Jenny Omma, Chris Mattinson, Eduardo Garzanti Nov 2017

High Throughput Petrochronology And Sedimentary Provenance Analysis By Automated Phase Mapping And Laicpms, Pieter Vermeesch, Martin Rittner, Ethan Petrou, Jenny Omma, Chris Mattinson, Eduardo Garzanti

All Faculty Scholarship for the College of the Sciences

The first step in most geochronological studies is to extract dateable minerals from the host rock, which is time consuming, removes textural context, and increases the chance for sample cross contamination. We here present a new method to rapidly perform in situ analyses by coupling a fast scanning electron microscope (SEM) with Energy Dispersive X-ray Spectrometer (EDS) to a Laser Ablation Inductively Coupled Plasma Mass Spectrometer (LAICPMS) instrument. Given a polished hand specimen, a petrographic thin section, or a grain mount, Automated Phase Mapping (APM) by SEM/EDS produces chemical and mineralogical maps from which the X-Y coordinates of the datable …


Pliocene Sinistral Slip Across The Adobe Hills, Eastern California-Western Nevada: Kinematics Of Fault Slip Transfer Across The Mina Deflection, Sarah Nagorsen-Rinke, Jeffrey Lee, Andrew Calvert Jan 2013

Pliocene Sinistral Slip Across The Adobe Hills, Eastern California-Western Nevada: Kinematics Of Fault Slip Transfer Across The Mina Deflection, Sarah Nagorsen-Rinke, Jeffrey Lee, Andrew Calvert

All Faculty Scholarship for the College of the Sciences

The Adobe Hills region (California and Nevada, USA) is a faulted volcanic field located within the western Mina deflection, a right-stepping zone of faults that connects the northern Eastern California shear zone (ECSZ) to the south with the Walker Lane belt (WLB) to the north. New detailed geologic mapping, structural studies, and 40Ar/39Ar geochronology in the Adobe Hills allow us to calculate fault slip rates and test predictions for the kinematics of fault slip transfer into the Mina deflection. The Adobe Hills are dominated by Pliocene tuffaceous sandstone, basaltic lavas that yield 40Ar/39Ar ages …


Geochemistry, Geothermobarometry And Geochronology Of High-Pressure Granulites And Implications For The Exhumation History Of Ultrahigh-Pressure Terranes: Dulan, Western China, Benjamin David Joseph Christensen Jan 2011

Geochemistry, Geothermobarometry And Geochronology Of High-Pressure Granulites And Implications For The Exhumation History Of Ultrahigh-Pressure Terranes: Dulan, Western China, Benjamin David Joseph Christensen

All Master's Theses

The Dulan ultrahigh-pressure (UHP) rocks of the North Qaidam terrane, Western China, represent continental crust that has been subducted ~100 km during continental collision. Adjacent granulites representing burial to ~50 km could either be overprinted eclogites or a separate high-pressure-high-temperature (HP-HT) granulite unit. Overprinted eclogites and HP-HT granulites imply different P-T-t paths for UHP rocks. Metamorphic conditions for the granulites are 750–880 °C and 14–17 kbar. Zircon U-Pb geochronology, REE patterns and Ti-in-zircon thermometry indicate an increase in temperature from ~800 °C (449 Ma) to ~900 °C (418 Ma). This temperature increase could explain the presence of granulite leucosomes and …