A relation among geology, tectonics, and velocity structure, western to central Nevada Basin and Range

Abstract

Research Article| September 01, 1992 A relation among geology, tectonics, and velocity structure, western to central Nevada Basin and Range R. D. CATCHINGS R. D. CATCHINGS 1U.S. Geological Survey, 345 Middlefield Road, M.S. 977, Menlo Park, California 94587 Search for other works by this author on: GSW Google Scholar Author and Article Information R. D. CATCHINGS 1U.S. Geological Survey, 345 Middlefield Road, M.S. 977, Menlo Park, California 94587 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1992) 104 (9): 1178–1192. https://doi.org/10.1130/0016-7606(1992)104<1178:ARAGTA>2.3.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation R. D. CATCHINGS; A relation among geology, tectonics, and velocity structure, western to central Nevada Basin and Range. GSA Bulletin 1992;; 104 (9): 1178–1192. doi: https://doi.org/10.1130/0016-7606(1992)104<1178:ARAGTA>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract In the northwestern to central Nevada Basin and Range, there are correlations between velocity and specific geologic structures of the crust. Mapped range-bounding faults at the surface can be traced to appreciable (10 km) depths based on velocity variations and are consistent with subsurface projections of the faults based on seismic reflection images. The limiting depth of the faults, as indicated by the velocity variations, corresponds to the maximum depth of earthquakes along the seismic profile. Correlations between velocity and the surface geology show that in the upper crust the pre-Cenozoic rocks are underlain by high-velocity (6.0 km/s) rocks, whereas the Tertiary ranges are underlain by lower-velocity (4.0-5.7 km/s) rocks to depths as great as 10 km. Although the Tertiary rocks differ in composition from the Mesozoic rocks, the lower-velocity Tertiary rocks may also be attributed to rock masses which are broken (4.0-5.7 km/s), and the higher-velocity Mesozoic rocks (6.0 km/s) may be attributed to largely unbroken rock masses. The regional seismicity pattern is consistent with this interpretation, as earthquakes are largely confined within or near the base of the low-velocity rocks. These low-velocity, highly fractured rocks are laterally distributed in discrete zones, suggesting that extension is not uniformly distributed but occurs in discrete, highly extended zones. Beneath these highly extended zones, the lower-crustal layers show structural evidence of extension, and velocity measurements suggest that the lowermost crust has been magmatically underplated. The superposition of Tertiary volcanic rocks, highly fractured upper crust, and lower-crustal magmatic underplating suggests that the Tertiary volcanic rocks originated from lower-crustal magmas that migrated to the surface via the highly extended zones. The velocity structure of one of the highly extended zones and the Lahonton Basin resembles that of many continental rifts. The velocity structure beneath central Nevada, however, is much more like normal continental crust. On the basis of isotopic studies, it is concluded that the transition between highly extended crust and more normal crust occurs in the area inferred to be the edge of the North American craton. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.