Award Date

5-15-2018

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Geoscience

First Committee Member

Wanda Taylor

Second Committee Member

Rodney Metcalf

Third Committee Member

Ganquing Jiang

Fourth Committee Member

Barbara Luke

Number of Pages

80

Abstract

The Basin and Range province is characterized by normal faults associated with

extension, but the occurrence of strike-slip faults and the seismic hazard accompanying

them is less understood. One major strike-slip zone, the Pahranagat shear zone (PSZ),

lies in Lincoln County, Nevada and within the boundary zone between northern Basin

and Range (NBR) and central Basin and Range (CBR) sub-provinces. The PSZ is a 20-

25 km long zone of Cenozoic left-lateral faults. The Arrowhead Mine Fault (AMF) is one

of the three major faults in the PSZ. The western AMF and the faults that surround and

abut it are the foci of this research. The purpose of this research is to understand the

timing and style of deformation of the AMF, the PSZ, and the relationship of the PSZ to

regional tectonics. I hypothesize that the AMF is a recent tectonic feature that supports

a model of regional sinistral transfer between tectonic regimes. The best way to obtain

the spatial and geometric data needed to address the issue was detailed mapping with

emphasis on fault cross-cutting, termination, and kinematic relationships at 1:12,000

scale of the western AMF and surrounding area in the East Pahranagat Range.

New fault data, and stereographic analysis of bedding and compaction foliation data

along with cross sections and a fence diagram provide evidence that the normal faults

and strike-slip fault are kinematically compatible and were active synchronously,

indicating that the AMF is a transfer fault. Strike-slip fault splays form a flower

structure/duplex that are shown to have formed synchronously with a number of normal

faults in the area. Internally, the duplex contains both contractional and extensional

structures, divided by a through-going fault. This situation is uncommon in models of

duplex formation, but is suggested here to have formed during segment linkage.

Cross-cutting relationships indicate that the AMF cuts Kane Wash Tuff, Gregerson

Basin Member, along one strand, constraining the age to ~15 Ma or younger. By

constraining the age and style of deformation of the AMF we find that the PSZ was

active late in the development of the NBR to CBR boundary zone.

The PSZ plays a distinct role in the intraplate tectonics of the region, falling within the

Southern Nevada Seismic Belt. It may be facilitating strain transfer from other sinistral

structures within the Southern Nevada Seismic Belt (Caliente-Enterprise Zone, Rock

Valley Fault Zone, etc.). The presence of both a western termination of the AMF and a

gap in left-lateral structures to the west suggest that the NBR-CBR boundary is still

developing, which has implications for the interconnectivity of Walker Lane with the

Intermountain Seismic Belt and has implications for seismic hazard.

Keywords

faulting; flower structure; nevada; Seismicity; structural; tectonics

Disciplines

Geology

Language

English


Included in

Geology Commons

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