Award Date

1-1-1998

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Geoscience

First Committee Member

Rodney V. Metcalf

Number of Pages

82

Abstract

Mafic magmas play a significant role in the evolution of calc-alkaline magma systems in convergent and extensional environments. The Miocene Mt. Perkins pluton, northwestern Arizona, was emplaced as a series of four discrete magma pulses into a country rock of Precambrian orthogneiss. Phase 1 is a gabbro-diorite containing four rock groups: olivine-clinopyroxene cumulates, hornblende-plagioclase cumulates, homblende gabbro, and quartz diorite. Stage one of phases 2 and 3 evolved by a process of fractional crystallization of an asthenospheric mantle derived mafic magma and magma mixing with an upper crustal granitic magma. Phase 1 magmas evolved by fractional crystallization (required by the presence of cumulates) of an asthenospheric mantle derived mafic magma and contamination by an asthenospheric-lithospheric mantle derived basaltic magma at depth and the orthogneiss at emplacement level. Phases 1, 2, and 3 share a common asthenospheric mantle derived magma. Mafic mantle derived melts are generated continuously throughout magma system evolution.

Keywords

Alkaline; Arizona; Arizonaimplications Derived; Diorite; Evolution; Gabbro; Implications; Mafic; Magma; Magmas; Mantle; Miocene Northwest; Perkins; Petrogenesis; Phase; Pluton; Role

Controlled Subject

Geology; Geochemistry

File Format

pdf

File Size

2017.28 KB

Degree Grantor

University of Nevada, Las Vegas

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