Award Date

1-1-2000

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Geoscience

First Committee Member

Eugene I. Smith

Number of Pages

83

Abstract

The Kingman Arch is a structurally high area in southern Nevada and northwestern Arizona that lies partially within the Colorado River Extensional Corridor. Apatite fission track and 40Ar/39Ar thermochronological analyses were conducted for granite samples collected from a 4.5 kilometer thick Precambrian section in the central McCullough Range. 40Ar/ 39Ar data suggest slow cooling of the Kingman Arch between 1000 to about 560 Ma. Cessation of cooling is coincident with deposition of the Cambrian Tapeats Sandstone. Paleozoic and Mesozoic strata are absent on the Kingman Arch, but are present in areas adjacent to it. Thermal modeling suggests differential cooling of the crust, possibly caused by crustal refrigeration. The faster cooling of samples lower in the section compared to those in the upper part may be evidence of this refrigeration event. Nearly 5.5 kilometers of Mesozoic, Paleozoic, and Precambrian strata were removed from the Kingman Arch between the onset of Sevier thrust faulting (146 Ma) and deposition of the Peach Springs Tuff (18.5 Ma). The McCullough Spring conglomerate (MSC) was deposited in channels on the Precambrian basement between 40 and 18.5 Ma. The MSC contains Precambrian crystalline, Neoproterozoic quartzite, and Paleozoic carbonate clasts. Studies of clast type and provenance, together with qualitative analysis of paleoflow indicators, suggest that sediment was eroded from the Kingman Arch and highlands to the west and transported to the east and northeast.

Keywords

Arch; Evolution; Kingman; Nevada; Southern

Controlled Subject

Geology

File Format

pdf

File Size

3061.76 KB

Degree Grantor

University of Nevada, Las Vegas

Language

English

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