Regional Geology of Mount Diablo, California: Its Tectonic Evolution on the North America Plate Boundary
CONTAINS OPEN ACCESS

Mount Diablo and the geology of the Central California Coast Ranges are the subject of a volume celebrating the Northern California Geological Society’s 75th anniversary. The breadth of research illustrates the complex Mesozoic to Cenozoic tectonic evolution of the plate boundary. Recent faulting and folding along the eastern edge of the San Andreas system have exposed in the mountain a core of Franciscan accretionary wedge complex faulted against Cretaceous and Cenozoic forearc strata. The Memoir includes papers on structure, stratigraphy, tephrochronology, zircon provenance studies, apatite fission track analyses, and foraminifera and calcareous plankton assemblages tied to Cenozoic climate events. Chapters also address the history of geologic work in the area and the resource development of oil and gas, mercury, coal, and sand, and road aggregate.
Neogene volcanism on the eastside of Mount Diablo, Contra Costa County, California
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Published:September 27, 2021
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CiteCitation
Raymond Sullivan, Ryan P. Fay, Carl Schaefer, Alan Deino, Stephen W. Edwards, 2021. "Neogene volcanism on the eastside of Mount Diablo, Contra Costa County, California", Regional Geology of Mount Diablo, California: Its Tectonic Evolution on the North America Plate Boundary, Raymond Sullivan, Doris Sloan, Jeffrey R. Unruh, David P. Schwartz
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ABSTRACT
Two spatially separated areas of Neogene volcanic rocks are located on the northeast limb of the Mount Diablo anticline. The southernmost outcrops of volcanics are 6 km east of the summit of Mount Diablo in the Marsh Creek area and consist of ~12 hypabyssal dacite intrusions dated at ca. 7.8–7.5 Ma, which were intruded into the Great Valley Group of Late Cretaceous age. The intrusions occur in the vicinity of the Clayton and Diablo faults. The rocks are predominantly calc-alkaline plagioclase biotite dacites, but one is a tholeiitic plagioclase andesite. Mercury mineralization was likely concomitant with emplacement of these...
- andesites
- California
- Cenozoic
- chemical composition
- Coast Ranges
- Contra Costa County California
- Cretaceous
- dacites
- East Pacific
- faults
- Great Valley Sequence
- hypabyssal rocks
- igneous rocks
- intrusions
- lava flows
- Mendocino fracture zone
- Mesozoic
- Neogene
- North Pacific
- Northeast Pacific
- Pacific Ocean
- Tertiary
- United States
- Upper Cretaceous
- volcanic rocks
- volcanism
- whole rock
- Mount Diablo
- Lawlor Tuff
- Clayton Fault
- Los Medanos Hills
- Marsh Creek valley
- Diablo Fault
- Mount Diablo Anticline
- Perkins Canyon
- Chaparral Springs