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Erosion of tilted fault blocks and deposition of coarse sediments in half-graben basins during late stages of extension; Gold Butte area, Basin and Range Province

Keith A. Howard, L. Sue Beard, M. A. Kuntz, M. J. Kunk, A. M. Sarna-Wojcicki, M. E. Perkins and Ivo Lucchitta
Erosion of tilted fault blocks and deposition of coarse sediments in half-graben basins during late stages of extension; Gold Butte area, Basin and Range Province (in Miocene tectonics of the Lake Mead region, central Basin and Range, Paul J. Umhoefer (editor), L. Sue Beard (editor) and Melissa A. Lamb (editor))
Special Paper - Geological Society of America (June 2010) 463: 147-170

Abstract

The provenance and stratigraphic architecture of basin-filling Miocene sediments around the Gold Butte area, southern Nevada, and adjacent highlands record the erosion of fault blocks that progressively tilted during extension. This study focuses especially on upper Miocene correlatives of the red sandstone unit and the Muddy Creek Formation that were deposited during waning stages of extension. Upper parts of the underlying middle Miocene Horse Spring Formation are also addressed. The large east-tilted South Virgin-White Hills block, including the Gold Butte block, was the primary source of coarse detritus into the adjacent half-graben basins on both sides. Voluminous, very coarse-grained sediments were shed eastward down the back slope of this tilt block into the Grand Wash Trough. This suggests that there were large middle and late Miocene catchments on that side of the block, possibly inherited from a gentler dip slope early in the tilting history. The block uplifted and tilted during slip on the west-dipping South Virgin-White Hills normal fault that bounds the west side of the block. Its exposed footwall shed coarse-grained debris to the west. While the fault was active, this debris included rock-avalanche megabreccias. Longitudinal transport of coarse-grained sediment also occurred along the axes of basins on both sides of the block. In the late Miocene, fault death at ca. 10 Ma followed rotation of the South Virgin-White Hills fault, and the along-strike Quail Spring fault, from initial dips >55 degrees to dips <30 degrees . This cessation of faulting coincided with and likely caused an eastward shift in locus of faulting to the steeper Wheeler fault system. Coarse sediment shed from the South Virgin-White Hills tilt block gradually declined as deformation waned and limestone-rich sedimentation expanded onto the basin margins against the block. Where the rising sedimentary fills eventually bridged across the block and connected basins on either side, these bridge sites served to focus later integrated regional drainage--the Pliocene Colorado River. Progressive Miocene tilting of the highland block would have broadened its structural footwall on the west and narrowed its east-dipping back slope. Migration of the drainage divide by erosion and piracy, influenced by changing tilt slopes, can explain the modern position of the divide in the Gold Butte block as one that separates drainage roughly equally down the two sides.


ISSN: 0072-1077
EISSN: 2331-219X
Coden: GSAPAZ
Serial Title: Special Paper - Geological Society of America
Serial Volume: 463
Title: Erosion of tilted fault blocks and deposition of coarse sediments in half-graben basins during late stages of extension; Gold Butte area, Basin and Range Province
Title: Miocene tectonics of the Lake Mead region, central Basin and Range
Author(s): Howard, Keith A.Beard, L. SueKuntz, M. A.Kunk, M. J.Sarna-Wojcicki, A. M.Perkins, M. E.Lucchitta, Ivo
Author(s): Umhoefer, Paul J.editor
Author(s): Beard, L. Sueeditor
Author(s): Lamb, Melissa A.editor
Affiliation: U. S. Geological Survey, Menlo Park, CA, United States
Affiliation: Northern Arizona University, Department of Geology, Flagstaff, AZ, United States
Pages: 147-170
Published: 201006
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 85
Accession Number: 2010-088818
Categories: Structural geologySedimentary petrology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Includes appendix
Illustration Description: illus. incl. block diag., chart, 6 tables, geol. sketch maps
N36°00'00" - N36°15'00", W114°19'60" - W11°34'60"
Secondary Affiliation: U. S. Geological Survey, USA, United StatesUniversity of Saint Thomas, USA, United StatesUniversity of Utah, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201047
Program Name: USGSOPNon-USGS publications with USGS authors
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