Publication Date

2019

Document Type

Dissertation/Thesis

First Advisor

Walker, James A.

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Earth, Atmosphere and Environment

Abstract

The Taos Plateau volcanic field (TPVF) is located in Northern New Mexico between the eastern flanks of the Tusas Mountains and west of the Sangre de Cristo range. The TPVF is dominantly composed of basaltic lava flows, olivine andesites, and two-pyroxene dacites which erupted from 5.88 to 1.03 Ma. The variety of compositions within the field owes its origin to processes such as magma mixing, fractional crystallization, and crustal assimilation based on chemical modeling. Curiously placed within this spectrum of mafic to intermediate lavas exists the singular high-silica rhyolite of the No Agua Peaks. XRF and ICP-MS analyses from this study verify previous conclusions that the No Agua high-silica rhyolites can be split into two groups of contrasting chemistries. Specifically, the rhyolites of the West Peaks of No Agua are characterized by higher concentrations of Na2O and many incompatible trace elements (e.g.: Rb, Ta, Nb, Cs) and lower contents of CaO, Fe2O3, Al2O3, Sr, Ba, Eu and LREE relative to the rhyolites forming the remaining North, South and East (NSE) Peaks. These chemical differences cannot be explained by fractional crystallization, with or without assimilation. Instead, the rhyolites from the West Peaks and NSE Peaks are considered to be separate and isolated batch melts of Proterozoic crustal material. The Tres Piedras Granite is a possible crustal source for all of the No Agua rhyolites

Extent

84 pages

Language

eng

Publisher

Northern Illinois University

Rights Statement

In Copyright

Rights Statement 2

NIU theses are protected by copyright. They may be viewed from Huskie Commons for any purpose, but reproduction or distribution in any format is prohibited without the written permission of the authors.

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