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Refining Models Of Crustal Growth And Evolution In Southwestern Laurentia With Paired U-Pb And Lu-Hf Analyses Of Igneous And Detrital Zircon, Mark E. Holland
Refining Models Of Crustal Growth And Evolution In Southwestern Laurentia With Paired U-Pb And Lu-Hf Analyses Of Igneous And Detrital Zircon, Mark E. Holland
Earth and Planetary Sciences ETDs
The origin and evolution of continental crust is a fundamental and debated topic in geoscience. For over thirty years, Proterozoic crust of the southwestern United States has been a field laboratory for studying orogenic processes in the middle crust, and the growth of continental lithosphere via accretionary orogenesis. Three distinct crustal provinces are delineated based on differences in isotopic, structural, and geochronologic characteristics. To address questions about the origin of each province, this dissertation is composed of three chapters that present new U-Pb and Lu-Hf isotope analysis of plutonic, volcanic, and detrital zircon from the oldest known rocks in each …
Volatile Chemistry, And Nitrogen Sources And Fluxes, In Subduction Zones : Insights From The Izu-Bonin-Mariana Arc, Euan Mitchell
Volatile Chemistry, And Nitrogen Sources And Fluxes, In Subduction Zones : Insights From The Izu-Bonin-Mariana Arc, Euan Mitchell
Earth and Planetary Sciences ETDs
A systematic study of the geochemistry of volatiles being emitted from the active volcanic front of the Izu-Bonin-Mariana (IBM) arc was undertaken in order to investigate the sources, flux, and mass balance of nitrogen across this 'cool' convergent margin. The IBM arc is an ideal location to study volatile recycling in subduction zones as it is an intra-oceanic convergent margin (IOCM), where the entire sedimentary sequence is subducted and where a number of parameters, including sediment composition, slab dip and slab age, vary systematically along strike of the arc. Volcanic emissions are typical of convergent margin volcanoes, and are dominated …