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Salton Buttes : ウィキペディア英語版 | Salton Buttes
The Salton Buttes are a group of five small lava domes in the lower Coachella Valley, in Imperial County, California. They are the only active volcanoes in Southern California, and are associated with the East Pacific Rise.〔(USGS California Volcano Observatory ) - "The high heat flow from the area and relatively young age of Salton Buttes, however, attest to the potential for future eruptions." There are no other active volcanoes in Southern California.〕 The Salton Buttes include: Mullet Island, Obsidian Butte, Red Island, and Rock Hill. ==Geology==
The Salton Buttes domes are on the southeast shoreline of the Salton Sea and are associated with the Salton Sea geothermal field within the Salton Trough (Salton Sink).〔Robinson, Paul T., Wilfred A. Elders and L.J.P. MufflerR, ''Quaternary volcanism in the Salton Sea geothermal field, Imperial Valley, California,'' Geological Society of America Bulletin 1976;87;347-360〕 They are on the north margin of the Brawley seismic zone. Red Island is composed of two domes separated by some 200 m of Quaternary gravels.〔 They consist of rhyolite and volcanic activity may have occurred in 6450 BC. A 2012 study, however indicates the buttes may have last erupted more recently, between 940 and 0 BC.〔Oskin, Becky, "Salton Sea Volcano Mystery Solved," http://www.ouramazingplanet.com/3686-salton-buttes-younger.html, accessed Oct. 25, 2012〕〔Schmitt, Axel K., et al., ''(U-Th)/He zircon and archaeological ages for a late prehistoric eruption in the Salton Trough (California, USA),'' Geology, January 2013, v. 41, p. 7-10 (Abstract )〕 Within the geothermal area older Pleistocene age buried domes have been encountered in drilling operations.〔〔Wright, Heather M., et al. "Episodic Holocene eruption of the Salton Buttes rhyolites, California, from paleomagnetic, U‐Th, and Ar/Ar dating." Geochemistry, Geophysics, Geosystems (2015).〕
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