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

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doi: 10.1029/JB085iB05p02381
Authors:Duffield, W. A.; Bacon, C. R.; Dalrymple, G. B.
Author Affiliations:Primary:
U. S. Geol. Surv., Menlo Park, Calif., United States
Volume Title:Coso geothermal area
Volume Authors:Bacon, C. R., editor; Duffield, W. A.
Source:Coso geothermal area, edited by C. R. Bacon and W. A. Duffield. Journal of Geophysical Research, 85(B5), p.2381-2404. Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0148-0227
Publication Date:1980
Note:In English. 98 refs.; illus. incl. tables, geol. sketch map
Summary: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 ∼35 km3 of late Cenozoic volcanic rocks that were erupted during two periods, as defined by K-Ar dating: (1) 4.0-2.5 m.y., ∼31 km3 of basalt, rhyodacite, dacite, andesite, and rhyolite, in descending order of abundance, and (2) ≤1.1 m.y., nearly equal amounts of basalt and rhyolite, most of the rhyolite being ≤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 ≥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 response to lithospheric extension. [M.J. Le B.]
Subjects:Absolute age; Basin range structure; Cenozoic; Dates; Displacements; Economic geology; Faults; Geochronology; Geothermal energy; Geothermal fields; Geothermal systems; Heat sources; Igneous rocks; K/Ar; Magma chambers; Neotectonics; Normal faults; Reactivation; Structural geology; Tectonics; Upper Cenozoic; Vents; Volcanic rocks; Volcanism; Basin and Range Province; California; Coso Hot Springs KGRA; Coso Range; Inyo County California; North America; United States; Structure
Coordinates:N354500 N361500 W1173000 W1180000
Abstract Numbers:82M/2244
Record ID:1981000525
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute.
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