Quaternary volcanism in the Salton Sea geothermal field, Imperial Valley, California

Abstract

Research Article| March 01, 1976 Quaternary volcanism in the Salton Sea geothermal field, Imperial Valley, California PAUL T. ROBINSON; PAUL T. ROBINSON 1Department of Earth Sciences and Institute of Geophysics and Planetary Physics, University of California, Riverside, California 92502 Search for other works by this author on: GSW Google Scholar WILFRED A. ELDERS; WILFRED A. ELDERS 1Department of Earth Sciences and Institute of Geophysics and Planetary Physics, University of California, Riverside, California 92502 Search for other works by this author on: GSW Google Scholar L.J.P. MUFFLER L.J.P. MUFFLER 2U.S. Geological Survey, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar Author and Article Information PAUL T. ROBINSON 1Department of Earth Sciences and Institute of Geophysics and Planetary Physics, University of California, Riverside, California 92502 WILFRED A. ELDERS 1Department of Earth Sciences and Institute of Geophysics and Planetary Physics, University of California, Riverside, California 92502 L.J.P. MUFFLER 2U.S. Geological Survey, Menlo Park, California 94025 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1976) 87 (3): 347–360. https://doi.org/10.1130/0016-7606(1976)87<347:QVITSS>2.0.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 PAUL T. ROBINSON, WILFRED A. ELDERS, L.J.P. MUFFLER; Quaternary volcanism in the Salton Sea geothermal field, Imperial Valley, California. GSA Bulletin 1976;; 87 (3): 347–360. doi: https://doi.org/10.1130/0016-7606(1976)87<347:QVITSS>2.0.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 The Salton Sea geothermal field lies in the Salton Trough, the landward extension of the Gulf of California, an area of active crustal spreading. Surface volcanic rocks of the field consist of five small rhyolite domes extruded onto Quaternary sediments of the Colorado River delta. Two domes are linked by subaqueous pyroclastic deposits; the others are single extrusions with or without marginal lava flows. The domes are low-calcium, alkali rhyolite with 1 to 2 percent crystals. Similar silicic rocks found in wells have been extensively altered by geothermal brines.Basaltic rocks occur as xenoliths in the domes and as subsurface dikes, sills, or flows. The xenoliths consist of low-potassium tholeiitic basalt similar to that of the East Pacific Rise. Subsurface basaltic rocks are mineralogically similar to the xenoliths but have undergone extensive hydrothermal alteration.Numerous partly melted granitic xenoliths in the domes show various degrees of either cotectic melting along quartz-feldspar grain boundaries or disequilibrium incongruent melting of hydrous ferro-magnesian minerals. These rocks are sodic granite containing notably higher SiO2, CaO, and Na2O and lower total iron than the enclosing rhyolite. Compositions and textures suggest that the granite xenoliths are fragments of basement rather than the crystallized equivalents of the rhyolite magma.The bimodal basalt-rhyolite assemblage of the Salton Sea geothermal field is believed to have formed by partial fusion in two stages of mantle peridotite, forming successive rhyolitic and basaltic melts. After formation, the rhyolitic magma was partly contaminated by continental crust material. 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.