Award Date

1-1-1989

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Geoscience

First Committee Member

E. I. Smith

Number of Pages

77

Abstract

Geochemical, isotopic, paleomagnetic, and geochronological studies of Late Miocene to Pliocene alkalic basalt in the upper Grand Wash Trough, Arizona and at Gold Butte, Nevada may place constraints on the petrogenetic history of the basalt and on the geometry of the crustal structures that may have served as conduits; Geochemical modelling suggests that type B basalt can be derived from independent batch melts of spinel peridotite with limited fractionation (5 to 9% olivine plus Fe-Ti oxide); The Sr, Nd and Pb isotopic data confirm the geochemical models and indicate that all three magma types are mantle derived; The restricted range in geochemical diversity, the lack of extensive fractionation suggested by geochemical modelling, combined with a similarity of paleomagnetic poles and a lack of paleosols or uncomformities in the flow stacks of type B basalt flows, suggests that the eruptive episode for type B lavas was short lived. (Abstract shortened with permission of author.).

Keywords

Alkalic; Arizona; Basalt; Basin; Boundary; Cenozoic; Eastern; Petrogenesis; Range; Grand Wash Trough; Gold Butte; Nevada

Controlled Subject

Geology

File Format

pdf

File Size

3031.04 KB

Degree Grantor

University of Nevada, Las Vegas

Language

English

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