Award Date

1-1-1996

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Geoscience

First Committee Member

Wanda J. Taylor

Number of Pages

129

Abstract

In the northern Hiko Range, extension occurred in four temporally distinct episodes during the Cenozoic. The extensional events are (1) prevolcanic ({dollar}>{dollar}27.31 {dollar}\pm{dollar} 0.03 Ma), (2) synvolcanic (between 22.78 {dollar}\pm{dollar} 0.03 and 18.5 {dollar}\pm{dollar} 0.4 Ma), (3) Tertiary (?) postvolcanic ({dollar}<{dollar}14.7 {dollar}\pm{dollar} 0.4 Ma), and (4) Pliocene (?)-Quaternary. Four fault sets are delineated based on orientation and cross-cutting relationships: (1) northeast- to northwest-striking moderately dipping prevolcanic faults, (2) east-west-striking, steeply dipping synvolcanic faults, (3) east-west- and east-northeast-striking, steeply dipping Tertiary (?) postvolcanic faults, and (4) generally north-striking steeply dipping Pliocene (?)-Quaternary faults; Prevolcanic faults in the northern Hiko Range are interpreted to be footwall faults to an Oligocene age extensional system. These faults increase the area known to be affected by Oligocene extension and support existing evidence that suggests this event is widespread; A tectonomagmatic rift model has been proposed to explain synvolcanic extension during the Tertiary in the northern Basin and Range province. However, the majority of the faults are postvolcanic and are not readily explained by the tectonomagmatic rift model. Both east-west- and east-northeast-striking oblique-slip faults occur along the Timpahute lineament. They appear to be the result of stresses produced by the Tertiary southward sweep of volcanism, in combination with a reduction of plate boundary stresses, which occurred after volcanism; The Hiko fault zone is a segmented fault of Pliocene (?)-Quaternary age that may still be active and is interpreted to be the bounding fault of a half graben in Pahranagat Valley. (Abstract shortened by UMI.).

Keywords

County; Geology; Hiko; Lincoln; Nevada; Northern; Range; Structures

Controlled Subject

Geology

File Format

pdf

File Size

3471.36 KB

Degree Grantor

University of Nevada, Las Vegas

Language

English

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