Clear Lake Volcanic Field

Clear Lake Volcanic Field
Name	Clear Lake Volcanic Field
Location	Lake County, California, United States
Type	volcanic field
Age	Pleistocene–Holocene
Last eruption	~10,000–11,000 years BP

Clear Lake Volcanic Field is a volcanic field in Lake County, California, United States, centered near Clear Lake and extending across the Mayacamas Mountains and adjacent terrain. The field encompasses volcanic centers, obsidian domes, cinder cones, and hydrothermal features that have been studied by institutions such as the United States Geological Survey, University of California, Berkeley, University of California, Davis, and Lawrence Berkeley National Laboratory. The volcanic field lies within a region influenced by the tectonics of the Pacific Plate, North American Plate, and the complex transform and subduction interactions near the Mendocino Triple Junction and San Andreas Fault system.

Geology and Volcanic Features

The volcanic field contains a suite of volcanic landforms including rhyolitic lava domes, obsidian flows, and cinder cones produced during the late Pleistocene to Holocene, mapped and described by the United States Geological Survey, California Geological Survey, University of California, Berkeley, and Stanford University geologists. Prominent features adjacent to Clear Lake include obsidian-rich domes and flow units documented by researchers from Lawrence Livermore National Laboratory, Scripps Institution of Oceanography, and the Geological Society of America. The field overlies metamorphic basement rocks of the Franciscan Complex and Great Valley Sequence studied by the California Division of Mines and Geology, USGS, and University of California, Davis structural geologists. Regional geomorphology links to the Mayacamas Mountains, Coast Ranges, Mount Konocti, and Clear Lake basin as mapped by the National Park Service, California Department of Fish and Wildlife, and local county agencies.

Eruption History and Chronology

Eruptive episodes are recorded from middle Pleistocene through late Holocene, with radiocarbon and argon–argon dating performed by teams at Lawrence Berkeley National Laboratory, USGS, and University of California, Berkeley. Key eruptive centers produced obsidian flows and ash layers correlated to stratigraphy used by the Geological Society of America, American Geophysical Union, and Quaternary Research community. Tephrochronology links eruptions to regional ash deposits identified by the United States Geological Survey, California Geological Survey, and academic groups at Stanford University and the University of Oregon. Paleoindian and Native American archaeological studies by the Smithsonian Institution, University of California, Davis, and California State Parks have examined obsidian sourcing and trade related to eruptions in the late Holocene.

Petrology and Geochemistry

Rhyolitic to dacitic compositions dominate petrology studies conducted by the USGS, Carnegie Institution for Science, University of California, Berkeley, and Caltech petrologists, with geochemical analyses using facilities at Lawrence Berkeley National Laboratory and Scripps Institution of Oceanography. Major- and trace-element geochemistry, isotopic studies (Sr-Nd-Pb), and mineralogical investigations have been published in journals associated with the Geological Society of America, American Geophysical Union, and Journal of Petrology, linking magmas to crustal assimilation and fractional crystallization processes examined by researchers at Stanford University and the University of Arizona. Obsidian provenance work involving the Smithsonian Institution, University of California, Davis, and George Mason University has used geochemical fingerprinting to trace prehistoric exchange networks.

Tectonic Setting and Magma Sources

The volcanic field’s magmatism is linked to the tectonics of the Pacific Plate, North American Plate, Mendocino Triple Junction, and the San Andreas Fault system as analyzed by the USGS, California Institute of Technology, Scripps Institution of Oceanography, and University of California, Berkeley. Geophysical studies by Lawrence Berkeley National Laboratory, Lamont–Doherty Earth Observatory, and USGS deploy seismic tomography, gravity, and magnetotelluric surveys to image magma bodies and crustal structures beneath the Mayacamas Mountains and Clear Lake basin. Mantle and crustal contributions to magma genesis have been investigated by petrologists at Caltech, Carnegie Institution for Science, and University of Oregon, integrating data from the American Geophysical Union and Geological Society of America conferences.

Geothermal Activity and Hazards

Active hydrothermal systems, fumaroles, hot springs, and surface alteration have been documented by the USGS, California Energy Commission, Lawrence Berkeley National Laboratory, and Department of Energy, highlighting potential for geothermal energy exploration assessed by Pacific Gas and Electric Company and academic partners at University of California, Davis. Volcanic hazards including dome collapse, pyroclastic flows, ashfall, and seismicity have been evaluated in hazard assessments by the USGS, California Governor’s Office of Emergency Services, and Lake County officials, with monitoring supported by the National Oceanic and Atmospheric Administration, USGS Volcano Disaster Assistance Program, and regional universities. Risk analyses integrate studies from the American Geophysical Union, Geological Society of America, and state emergency planners.

Ecology, Land Use, and Conservation

The volcanic landscape intersects ecosystems and land uses managed by California Department of Fish and Wildlife, US Fish and Wildlife Service, California State Parks, University of California Natural Reserve System, and local conservation groups, supporting oak woodland, chaparral, and endemic species studied by researchers at University of California, Davis, and California Polytechnic State University. Land-use planning, water resources in the Clear Lake watershed, and conservation initiatives involve Lake County government, California Department of Water Resources, EPA, and non-profit organizations such as The Nature Conservancy and Audubon Society. Cultural resources and tribal stewardship by Pomo, Yuki, and other Native American communities have been integrated into management frameworks developed with the Smithsonian Institution, Bureau of Indian Affairs, and California State Historic Preservation Officer.

Category:Volcanic fields of California