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Geophysical constraints on the location and geometry of the Las Vegas Valley Shear Zone, Nevada
Author(s) -
Langenheim V. E.,
Grow J. A.,
Jachens R. C.,
Dixon G. L.,
Miller J. J.
Publication year - 2001
Publication title -
tectonics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.465
H-Index - 134
eISSN - 1944-9194
pISSN - 0278-7407
DOI - 10.1029/1999tc001159
Subject(s) - geology , structural basin , seismology , echelon formation , bedrock , fault (geology) , las vegas , shear zone , pull apart basin , alluvium , gravity anomaly , alluvial fan , detachment fault , geomorphology , shear (geology) , monocline , reflection (computer programming) , sedimentary basin , tectonics , paleontology , metropolitan area , medicine , pathology , oil field , computer science , extensional definition , programming language
We model the basin configuration beneath Las Vegas Valley, Nevada, on the basis of gravity, drillhole, and seismic reflection data. We locate and characterize the various strands of the Las Vegas Valley Shear Zone (LVVSZ) by variations in basin thickness beneath the valley. The pre‐Tertiary bedrock surface is complex, with subbasins buried beneath the flat alluvial surface of the valley. We suggest that these basins are formed from transtensional strain. Subbasins elongated N70°W and N50°W are interpreted as strike‐slip basins. The deepest subbasin is 5 km west of Frenchman Mountain and strikes N40°E. This basin probably formed by combined movement on nonparallel strands of the LVVSZ and an earlier episode of normal faulting. The basin thickness map constrains the minimum depth of the inferred detachment fault beneath Las Vegas Valley to at least 4 km. Seismic reflection data do not image a detachment fault in the upper 10 km beneath Las Vegas Valley. Our results also illustrate the utility of gravity in determining basinal structures and providing a three‐dimensional perspective in areas with limited seismic reflection control.