Late Cenozoic volcanism, geochronology, and structure of the Coso Range, Inyo County, California

Journal Article · Sat May 10 04:00:00 EDT 1980 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JB085iB05p02381· OSTI ID:5285918

Duffield, W A; Bacon, C R; Dalrymple, G B

The Coso Range lies at the west edge of the Great Basin, adjacent to the southern part of the Sierra Nevada. A basement complex of pre-Cenozoic plutonic and metamorphic rocks is partly buried by approx.35 km/sup 3/ of late Cenozoic volcanic rocks that were erupted during two periods, as defined by K-Ar dating: (1) 4.0--2.5 m.y., approx.31 km/sup 3/ of basalt, rhyodacite, dacite, andesite, and rhyolite, in descending order of abundance, and (2) < or =1.1 m.y., nearly equal amounts of basalt and rhyolite, most of the rhyolite being < or =0.3 m.y. old. Vents for the volcanic rocks of the younger period are localized on and near a horst of basement rocks within a concavity defined by the distribution of vents of the older period. The alignment of many vents and the presence of a considerable number of roughly north-trending normal faults of late Cenozoic age reflect basin and range tectonics dominated by roughly east-west lithospheric extension. Fumaroles, intermittently active thermal springs, and associated altered rocks occur within and immediately east of the central part of the field of Quaternary rhyolite, in an area characterized by various geophysical anomalies that are evidently related to an active hot-water geothermal system. This system apparently is heated by a reservoir of silicic magma at > or =8-km depth, itself produced and sustained through partial melting of crustal rocks by thermal energy contained in mantle-derived basaltic magma that intrudes the crust in repsonse to lithospheric extension.

• Research Organization: U.S. Geological Survey, Menlo Park, California 94025
• OSTI ID: 5285918
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 85:B5; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
150201* -- Geology &amp; Hydrology of Geothermal Systems-- USA-- (-1989)
ANDESITES
BASALT
CALIFORNIA
CENOZOIC ERA
COSO HOT SPRINGS
FLUIDS
FUMAROLIC FLUIDS
GEOLOGIC AGES
GEOLOGIC FAULTS
GEOLOGIC HISTORY
GEOLOGIC STRATA
GEOLOGIC STRUCTURES
GEOTHERMAL FIELDS
GEOTHERMAL FLUIDS
IGNEOUS ROCKS
NORTH AMERICA
RHYOLITES
ROCKS
USA
VOLCANIC ROCKS
VOLCANISM
WESTERN REGION