Pluton source varition over two magmatic pulses in the white-inyo range, central-eastern California : implications for paleozoic and mesozoic tectonic reconstructions

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] This dissertation uses compositions of plutons in the White-Inyo Range (WIR) of central-eastern California, which is an important tectonic boundary as it is the easternmost extent of the Mesozoic Cordilleran arc and the western edge of Basin and Range extension. The main goal of this dissertation is to understand the lithospheric structure of this area in relation to the broader regional tectonics. Chapters 2 and 3 specifically investigate the Eureka Valley-Joshua Flat-Beer Creek (EJB) composite arc pluton, from its source to emplacement. The EJB pluton is one of a small number of monzonitic plutons cotemporally emplaced with the primarily calc-alkaline North American Mesozoic Cordilleran arc. Mineral major and trace element compositions are used to show the crystallization sequence and pressures and temperatures of mineral crystallization. These data are used to make interpretations about the EJB pluton's formation from source to emplacement. Additionally, whole rock major and trace element compositions and isotopic data show that the EJB pluton has a unique source from the calc-alkaline plutons: an underplated, eclogitized oceanic island arc. Chapter 4 is a regional study of the WIR, and it includes whole rock major and trace element and isotopic data to interpret the three distinct sources of plutons: (1) the eclogitized oceanic island arc, (2) enriched lithospheric mantle, and (3) Proterozoic North American basement. Recognizing the timing of the generation of these plutons in relation to their sources is crutial to understanding the tectonic history of the WIR area. This dissertation presents tectonic model for western North America from the Early Proterozoic to Late Cretaceous