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Physical Sciences and Mathematics Commons™

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Louisiana State University

2016

Zircon

Articles 1 - 2 of 2

Full-Text Articles in Physical Sciences and Mathematics

Geologic Extremes Of The Nw Himalaya: Investigations Of The Himalayan Ultra-High Pressure And Low Temperature Deformation Histories, Dennis Girard Donaldson Jan 2016

Geologic Extremes Of The Nw Himalaya: Investigations Of The Himalayan Ultra-High Pressure And Low Temperature Deformation Histories, Dennis Girard Donaldson

LSU Doctoral Dissertations

This dissertation focuses on two extremes of orogenic development in the Himalaya: the timing of early ultra-high pressure related tectonics and the subsequent emplacement of the high grade Greater Himalayan Crystallines. The Himalayan orogeny is one of if not the best example of ongoing collisional systems, marked by the ongoing convergence of the Indian and Asian continents. The presence of coesite in the Tso Morari complex respresents subduction of the Indian continental crust to ultrahigh-pressure (UHP) conditions. However, the timing of UHP metamorphism is debated, creating an uncertainty in the calculation of subduction and exhumation rates. Petrologic and geochronologic analyses …

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Archean Geodynamic Conditions Using P-T Constraints Of The East Pilbara Craton Ttgs, Andrew Kody Webb Jan 2016

Archean Geodynamic Conditions Using P-T Constraints Of The East Pilbara Craton Ttgs, Andrew Kody Webb

LSU Master's Theses

We know very little about the tectonic setting present during the Hadean, but based on studies of surviving Hadean zircons, we know that a Hadean protocrust must have been established by at least 4.4 Ga (Kemp et al. 2010), and it must have also been able to accommodate minimum melt conditions (Harrison 2005). Tectonic models for Earth during the Hadean and Archean follow two trends: uniformitarianism and non-uniformitarianism. Uniformitarian models (following the famed geological concept that the present is the key to the past) argue that Hadean zircons and Archean rocks formed via processes akin to modern-style oceanic crust production …

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