Award Date

8-1-2015

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Geoscience

First Committee Member

Wanda J. Taylor

Second Committee Member

Brenda Buck

Third Committee Member

Brett McLaurin

Fourth Committee Member

Barbara Luke

Number of Pages

83

Abstract

The kinematics and origin of transfer, accommodation and strike-slip zones is of paramount significance in understanding continental extension. The Las Vegas Valley Shear Zone (LVVSZ) is a NW-striking right-lateral fault system in the central Basin and Range province. Despite its prominence among the structures of the region and its role in the regional tectonic development, little is understood about its eastern portion. The inadequately constrained trace of the LVVSZ along its eastern part contributes largely to the ambiguity of the time activity and role of the LVVSZ. The eastern part of LVVSZ lies in Nellis Dunes Recreational Area (NDRA), north of Frenchman Mountain. The area exposes structures, the red sandstone unit, the Muddy Creek Formation, the Las Vegas Formation and the Quaternary deposits. Previous mapping showed different structural configurations in the NDRA and suggested that the area under the NDRA formed as a pull-apart basin between the LVVSZ in the northern part of the area and the Munitions fault that lies to the south and bounds the northern end of the Frenchman Mountain block. However, some structural geometries are inconsistent with the regional pull-apart basin model of Nellis basin. Folds, Thrust Faults and Normal Faults developed in different areas in NDRA. Each part is dominated by distinct compressional and extensional orientations.

In this study, I collected and analyzed more detailed data and suggested a deformation model consistent with the entire fold and fault geometries. Large scale mapping (1:8,000) documented complex structural geometries and kinematics. Structural analysis showed that the area exhibits three different deformations. 1) The NW-striking LVVSZ developed in Miocene-Pliocene in the middle part of the area and stopped moving before the Quaternary. 2) In the Quaternary, a NE- oriented left-lateral accommodation zone developed in the middle part of the area overprinting the LVVSZ deformation. 3) The northern end of the Frenchman Mountain fault curves to the NE forming a left-lateral fault splay in the southern part of NDRA.

Keywords

Faults (Geology); Frenchman Mountain Fault; Las Vegas Valley Shear Zone; Muddy Creek Formation; Nellis Dunes; Plate tectonics--Mathematical models; Strike-slip faults (Geology)

Disciplines

Geology | Tectonics and Structure

Language

English

Geologic Map of Nellis Dunes Recreational Area.pdf (113237 kB)
Plate 1. Geologic map of Nellis Dunes Recreational Area

Geologic Cross-sections of Nellis Dunes Recreational Area.pdf (490 kB)
Plate 2. Geologic cross-sections of Nellis Dunes Recreational Area


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