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Document Type

Open Access

Degree Program

Geosciences

Degree Type

Master of Science (M.S.)

Year Degree Awarded

2013

Month Degree Awarded

February

Abstract

The Springerville Volcanic Field (SVF) is a monogenetic volcanic field located in east-central Arizona and is the southernmost of several late Pliocene to Holocene volcanic fields along the margin of the Colorado Plateau. It encompasses an area of over 3000 km2 and consists of over 450 vents, most of which are cinder cones, which produced mainly basaltic flows, between 2.1 and 0.3 Ma. About 85% of the SVF was previously mapped in detail by Condit, Crumpler and Aubele (1999). In the summers of 2010 and 2011, mapping was completed in the remaining portion of the field known as the Yellow Jacket Cienega Subdivision (YJC). The YJC area is of great interest because it arguably contains the youngest and most evolved flows and represents the convergence of several different geographic subdivisions. The completed dataset, including the chemical analysis of 575 samples, allows for further study of the petrogenetic evolution of the SVF, with possibilities for thermobarometry and distinguishing isotopic reservoirs. The source rock for the SVF lavas was determined to be a garnet lherzolite with a higher clinopyroxene to garnet ratio than typical garnet lherzolite. Based on the methods derived by Lee et al (2009), depth of melting ranged from 75km to 130km, though the majority lie between 107 and 115 km depth. This could be inferred as a range of depths of melting, beginning in the garnet range and extending shallower, or scatter due to the assumptions made for these calculations. Despite the fairly limited isotopic data, SVF lavas seem to be derived from a Prevalent Mantle (PREMA) reservoir, with input of an enriched component, which is likely due to crustal contamination. The completed dataset for the SVF represents a unique resource, useful not only in studying the petrogenetic evolution of this volcanic field, but as a yardstick for comparing similar volcanic occurrences.

First Advisor

Christopher Condit

SVF proc.pdf (24275 kB)
Lithologic Map of the YJC Subdivision

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