Twin Buttes (California)

The Twin Buttes are two cinder cone volcanoes{{sfn|Clynne|Muffler|2010|p=70}} that lie north of Lassen Peak{{cite gvp|vn=323040|name=Twin Buttes|date=2013|accessdate=January 11, 2023}} in Shasta County, California. The Twin Buttes reach a summit elevation of about {{convert|5351|ft|m}}.{{Ref|art1|[a]}} Nearby towns include Burney, Old Station, and Viola.{{cite web|url=https://volcanoes.usgs.gov/volcanoes/twin_buttes/|archiveurl=https://web.archive.org/web/20140201070259/https://volcanoes.usgs.gov/volcanoes/twin_buttes/|archive-date=February 1, 2014|title=Twin Buttes|publisher=United States Geological Survey|date=January 3, 2012|accessdate=March 14, 2023}} About 6,700 people live within {{Convert|30|km|mi|disp=flip}} of the volcanoes, though the population within {{convert|100|km|mi|disp=flip}} climbs to more than 260,000. The buttes are aligned north–northwest and lie at the center of the Bidwell Spring volcanic chain.{{sfn|Clynne|Muffler|2010|p=70}}

The Twin Buttes — and other volcanoes near Lassen Peak — are part of the Cascade Volcanic Arc, which was produced by subduction of the oceanic Juan de Fuca tectonic plate under the North American tectonic plate.{{sfn|Clynne|Robinson|Nathenson|Muffler|2012|p=8}}{{sfn|Muffler|Clynne|Calvert|Champion|2011|p=2177}} Volcanic activity in the region is also influenced by the westward expansion of the Basin and Range Province into the Cascades.{{sfn|Muffler|Clynne|Calvert|Champion|2011|p=2178}} Volcanism in the region encompasses a wide variety of eruption types, ranging from cinder cones to shield volcanoes. Eruptive activity has for the most part produced overlapping, mafic volcanoes through nonexplosive to weak explosive eruptions.{{sfn|Clynne|Robinson|Nathenson|Muffler|2012|p=8}} Volcanic activity during the Quaternary has produced basalt, basaltic andesite, and olivine tholeiite.{{sfn|Muffler|Clynne|Calvert|Champion|2011|p=2178–2179}} Other major volcanic centers near the Twin Buttes include the Yana, Maidu, Dittmar, and Latour centers, which were long-lived volcanic systems with magma ranging in composition from andesite to silicic rhyolite; these four systems are now eroded with extinct hydrothermal systems.{{sfn|Clynne|Robinson|Nathenson|Muffler|2012|p=8}}

The Bidwell Spring chain consists of five eruptive units including the Twin Buttes basalt. ⁴⁰Ar/³⁹Ar has placed two other deposits, basaltic andesite from Black Butte and andesite from Bidwell Spring, at 62,000 ± 10,000 years old and 68,000 ± 6,000 years old, respectively. These results suggest several small eruptions between 65,000 and 45,000 years ago from the Bidwell Spring chain.{{sfn|Germa|Perry|Quidelleur|Calvert|2019|p=38}} Two other basaltic andesite deposits from the chain have been described by the United States Geological Survey (USGS), which considers the Bidwell Spring chain as part of the Caribou Volcanic Field,{{sfn|Clynne|Muffler|2010|p=Sheet 2}}{{sfn|Clynne|Muffler|2010|p=Sheet 3}} a system of 11 eruptive sequences between 200,000 and 100,000 years ago with vents aligned with faults that focused surface volcanic activity.{{sfn|Muffler|Clynne|Calvert|Champion|2011|p=2179}} Basalt from the Twin Buttes overlies eruptive material from the Poison Lake Chain and the Cone Lake Chain, which are also within the Caribou Volcanic field.{{sfn|Muffler|Clynne|Calvert|Champion|2011|p=2179}} Twin Buttes basalt is overlain by basaltic andesite erupted during the late Pleistocene from an unnamed volcanic vent, which is thought to be between 45,000 and 25,000 years old.{{sfn|Clynne|Muffler|2010|p=70}}

Subfeatures of the formation include Red Rock Hill, which has an elevation of {{convert|1597|m|ft|disp=flip}}. Other nearby features include basaltic andesite and a distinct basalt deposit southeast and northeast of the Twin Buttes, respectively, both of which were produced by eruptive activity between 50,000 and 35,000 years ago.{{sfn|Clynne|Robinson|Nathenson|Muffler|2012|p=17}}

Located in an area that was highly active during the Quaternary, the Twin Buttes volcanoes formed during the late Pleistocene.{{sfn|Clynne|Muffler|2010|p=Sheet 1}}{{Ref|art2|[b]}} The North and South Twin Buttes erupted blocky, partially unvegetated lava flows that moved north toward the southeastern base of Burney Mountain, a lava dome, between 25,000 and 15,000 years ago, covering an area of {{convert|10.1|km2|sqmi|disp=flip}}. They have an overall volume of {{Convert|0.296|cumi|disp=flip}}.{{sfn|Clynne|Robinson|Nathenson|Muffler|2012|p=17}} Eruptive material consisted of basalt (including picrite basalt) and dacite. Basalt erupted from Twin Buttes forms part of the Bidwell Spring chain with an ⁴⁰Ar/³⁹Ar age of about 46,000 ± 3,000 years,{{sfn|Germa|Perry|Quidelleur|Calvert|2019|p=38}} covering an area of {{Convert|19.8|km2|sqmi|disp=flip}}. The basalt deposit has a total volume of {{convert|0.8|km3|cumi|disp=flip}}.{{sfn|Clynne|Robinson|Nathenson|Muffler|2012|p=17}} At the edges, lava flows are steep, with up to {{convert|10|m|ft|disp=flip}} of relief.{{sfn|Clynne|Muffler|2010|p=70}} The lava flows from the Twin Buttes are porphyritic with about 53% silica content; they have vesicular surfaces and dense interiors. Phenocrysts range from {{convert|0.5|to|1|mm|in|disp=flip}}; there are also coarse xenoliths of quartz throughout the lava flows.{{sfn|Clynne|Muffler|2010|p=70}} Cinder and volcanic ash erupted by the Twin Buttes extend to the east.{{sfn|Clynne|Muffler|2010|p=70}}

While Twin Buttes last erupted during the late Pleistocene, the area is still monitored by the USGS given its proximity to Lassen Peak. As of 2012, there were three GPS receivers continuously monitoring Twin Buttes for deformation, an indicator of pre-eruptive activity.{{cite web|url=http://volcanoes.usgs.gov/volcanoes/twin_buttes/twin_buttes_monitoring_73.html|title=Deformation monitoring at Twin Buttes|date=January 3, 2012|archive-date=March 12, 2013|archive-url=https://web.archive.org/web/20130312130024/http://volcanoes.usgs.gov/volcanoes/twin_buttes/twin_buttes_monitoring_73.html|publisher=United States Geological Survey}} In 2014, the USGS considered Twin Buttes to have "low to very low" threat potential for a future eruption.{{Cite news|url=https://www.latimes.com/local/lanow/la-me-ln-quakes-mammoth-lakes-volcanoes-20140926-story.html|title=Mammoth Lakes earthquake swarm tied to water pressure, tectonic stress|last=Rocha|first=V.|date=September 27, 2014|accessdate=March 14, 2023|work=Los Angeles Times}}

• List of volcanoes in the United States

• [a] {{note|art1}} The Global Volcanism Program of the Smithsonian Institution lists the Twin Buttes summit elevation as {{convert|5351|ft|m}}. However, the Geographic Names Information System lists its elevation as {{convert|5341|ft|m}}.

• [b] {{note|art2}} The Global Volcanism Program lists Twin Buttes as a Pleistocene volcano. Archived materials published by the United States Geological Survey lists it as late Pleistocene or early Holocene.

{{reflist}}

• {{cite map|last1=Clynne|first1=M.A.|last2=Muffler|first2=L.J.P.|title=Geologic Map of Lassen Volcanic National Park and Vicinity, California|url=https://pubs.usgs.gov/sim/2899/data/sim2899_pamphlet.pdf|publisher=United States Geological Survey|id=Scientific Investigations Map 2899|date=December 30, 2010}}
• {{cite report|last1=Clynne|first1=M.A.|last2=Robinson|first2=J.E.|last3=Nathenson|first3=M.|last4=Muffler|first4=L.J.P.|year=2012|title=Volcano hazards assessment for the Lassen region, northern California: U.S. Geological Survey Scientific Investigations Report 2012–5176–A|publisher=United States Geological Survey|scale=1:200,000|url=https://pubs.usgs.gov/sir/2012/5176/a/sir2012-5176-a_text.pdf}}
• {{cite journal|last1=Germa|first1=A.|last2=Perry|first2=C.|last3=Quidelleur|first3=X.|last4=Calvert|first4=A.|last5=Clynne|first5=M.|last6=Connor|first6=C.B.|last7=Connor|first7=L.J.|last8=Malservisi|first8=R.|last9=Charbonnier|first9=S.|title=Temporal relationship between the Lassen volcanic center and mafic regional volcanism|date=June 7, 2019|journal=Bulletin of Volcanology|volume=81|issue=38|page=38 |publisher=Springer Science+Business Media|doi=10.1007/s00445-019-1296-7 |bibcode=2019BVol...81...38G |s2cid=195240340 }}
• {{cite journal|last1=Muffler|first1=L.J.P.|last2=Clynne|first2=M.A.|last3=Calvert|first3=A.T.|last4=Champion|first4=D.E.|url=https://pubs.geoscienceworld.org/gsa/gsabulletin/article/123/11-12/2177/125589/Diverse-discrete-mantle-derived-batches-of-basalt|title=Diverse, discrete, mantle-derived batches of basalt erupted along a short normal fault zone: The Poison Lake chain, southernmost Cascades|date=November 1, 2011|publisher=Geological Society of America|journal=Geological Society of America Bulletin|volume=123|issue=11–12|pages=2177–2200|doi=10.1130/B30370.1|bibcode=2011GSAB..123.2177M }}

Category:Volcanoes of California

Category:Cascade Volcanoes

Category:Subduction volcanoes

Category:Cinder cones of the United States

Category:Cascade Range

Category:Volcanoes of Shasta County, California

Category:Pleistocene cinder cones