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Titanium in quartz during growth and deformation under hydrothermal-magmatic conditions
(University of Oregon, 2020-12-08) Acosta, Marisa; Reed, Mark
DISSERTATION ABSTRACT Marisa Dawn Acosta Doctor of Philosophy Department of Earth Sciences September 2020 Title: Titanium in quartz during growth and deformation under hydrothermal-magmatic conditions Titanium in quartz is a promising tool with which to investigate processes of quartz growth and deformation. In this dissertation, I present and interpret the results of experimentally synthesized Ti-doped quartz crystals and shed light on sources of complexity that arise during non-equilibrium growth at 800℃ and 1 kbar. I use images of the Ti distributions in quartz from the Butte, Montana, porphyry Cu-Mo deposit to detail the sequence of events by which barren quartz and quartz-molybdenite veins are formed. I compare temperature estimates made with Ti concentrations to other independent methods of temperature estimates to show that the dark growth bands of CL-euhedral hydrothermal quartz record near-equilibrium growth and that the bright growth bands of CL-euhedral quartz are markers of disequilibrium “kinetic effects”. Lastly, I present a possible mechanism for the formation of oscillatory CL-bright and -dark growth bands under constant pressure and temperature conditions at low supersaturation. This dissertation includes previously published and unpublished co-authored material.