This article was accepted into the corpus but its outbound wikilinks were never NER-processed — typical at the deepest BFS hop or when the run's entity cap was reached. No expansion funnel to show.
| Clear Lake Volcanics | |
|---|---|
| Name | Clear Lake Volcanics |
| Location | Lake County, California, United States |
| Type | Volcanic field / complex |
| Coordinates | 38°57′N 122°38′W |
| Elevation m | 400–1400 |
| Last eruption | ~10,000–11,000 years BP (Holocene) |
Clear Lake Volcanics The Clear Lake Volcanics are a young silicic to intermediate volcanic field in northern California near Clear Lake, situated within Lake County, California and adjacent to Mendocino County, California. The volcanic field is spatially associated with the Geysers Geothermal Field, the San Andreas Fault, and the Mendocino Triple Junction, and it has produced rhyolitic domes, basaltic andesites, and pyroclastic deposits during the late Pleistocene and Holocene epochs. The region is significant for studies linking magmatism, hydrothermal systems, and crustal tectonics in western North America.
The Clear Lake Volcanics occupy a volcanic complex that links to regional tectonic features such as the San Andreas Fault system, the Pacific Plate, and the North American Plate, and lies near volcanic provinces including the Cascade Range and the Mendocino Fracture Zone. Prominent nearby places and institutions involved in research include the University of California, Berkeley, the United States Geological Survey, and the California Department of Conservation. The area includes volcanic centers, geothermal fields, and lacustrine basins such as Clear Lake and is adjacent to landforms like the Mayacamas Mountains.
Rocks from the field range from high-silica rhyolites to intermediate andesites and basalts; petrologic studies reference affinities to magmatic suites studied at Medicine Lake Volcano, Lassen Peak, and other northern California volcanic centers. Geochemical analyses by groups at Stanford University, University of California, Davis, and the U.S. Geological Survey emphasize trace elements and isotopic ratios comparable to magmas of the Sierra Nevada foothills and the Great Valley Sequence. Observed mineral assemblages include quartz, sanidine, biotite, hornblende, plagioclase, and clinopyroxene similar to suites from Mount Shasta and Mount Mazama.
Stratigraphic frameworks integrate radiocarbon dating, potassium-argon dating, and argon-argon geochronology; ages span late Pleistocene to Holocene, with some eruptions dated to ~10,000–11,000 years BP. Stratigraphy correlates volcanic units with lacustrine sediments of Clear Lake and tephra layers recognized in cores linked to regional records from sites such as Suisun Bay and Sacramento River Delta. Key mapped units have been described in surveys by the USGS and the California Geological Survey.
Eruptive centers include multiple rhyolite domes, scoria cones, and extensive lava flows; named local centers and complexes are commonly cited in geological maps by the USGS and academic publications from UC Berkeley and UC Davis. Historical eruptive interpretations draw comparisons with eruption styles at Mono-Inyo Craters and Long Valley Caldera, with explosive pyroclastic events and effusive dome growth documented through field mapping and stratigraphic studies. Interaction with basin-forming processes that affected Clear Lake and surrounding drainage systems has been emphasized in regional tectonic syntheses presented by researchers at Stanford University.
The volcanic terrain features domes, flow lobes, tuff rings, and cinder cones that have influenced topography of the Mayacamas Mountains and shoreline morphology of Clear Lake. Hydrothermal alteration, fumaroles, hot springs, and sinter deposits link the volcanic field to the Geysers Geothermal Field, a major site of geothermal power development operated by entities including Calpine Corporation and monitored by the California Energy Commission. Surface manifestations have been mapped alongside geothermal wells, alteration zones, and spring systems documented by the USGS and state agencies.
Hazards include future dome-building eruptions, pyroclastic flows, ashfall affecting communities such as Clearlake, California, Lakeport, California, and Kelseyville, California, and secondary hazards like lahars and hydrothermal explosions near altered ground. Monitoring involves seismic networks maintained by the USGS, regional earthquake centers like the Northern California Seismic System, and research seismology groups at UC Berkeley. Hazard assessments integrate data from regional fault studies including the San Andreas Fault and the Mendocino Triple Junction.
The Clear Lake area hosts geothermal resources exploited at the Geysers Geothermal Field, one of the world’s largest dry-steam fields supplying power to utilities regulated by the California Public Utilities Commission and developed by companies such as Calpine Corporation. Mineral occurrences including mercury were historically extracted at mines like those documented near Sulphur Bank Mine, and studies by the USGS and the California Department of Conservation have assessed environmental impacts and resource potential. Geothermal exploration has drawn interest from energy researchers at Lawrence Berkeley National Laboratory.
Significant research has been published by investigators affiliated with USGS, UC Berkeley, Stanford University, UC Davis, and national laboratories including Lawrence Livermore National Laboratory, covering petrology, geochronology, geothermal systems, and volcanic hazards. Notable studies include geochemical syntheses, argon-argon dating campaigns, and integrated tectono-magmatic models that relate the field to regional processes at the Mendocino Triple Junction, San Andreas Fault, and broader Pacific Northwest volcanism. Ongoing monitoring and interdisciplinary projects continue to involve universities, state agencies, and federal research institutions.
Category:Volcanoes of California Category:Geology of Lake County, California