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.
Interaction of extensional, contractional, and strike-slip elements at Mount Diablo and the surrounding eastern Coast Ranges, San Francisco Bay area, California: A model-based analysis
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Published:September 27, 2021
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CiteCitation
Donald A. Medwedeff*, 2021. "Interaction of extensional, contractional, and strike-slip elements at Mount Diablo and the surrounding eastern Coast Ranges, San Francisco Bay area, California: A model-based analysis", 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
This study presents three regional cross sections, a structural map analysis, and a schematic map restoration. The sections are constrained by surface geology and petroleum wells and were developed using model-based methods to be consistent with the regional tectonic context and balancing concepts. Together, these products depict the geometry and kinematics of the major fault systems. Insights from this research include the following. Franciscan complex blueschist-facies rocks in the Mount Diablo region were unroofed west of their current location and subsequently thrust beneath the Great Valley sequence in the mid-Eocene. East Bay structures are complicated by overprinting of Neogene compression and dextral strike-slip motion on a Paleogene graben system. Net lateral displacement between the Hayward fault and the Central Valley varies from 26 km toward 341° to 29 km toward 010° in the southern and northern East Bay Hills, respectively. Uplift above a wedge thrust generates the principal Neogene structural high, which extends from Vallejo through Mount Diablo to the Altamont Ridge. Anomalous structural relief at Mount Diablo is due to strike-parallel thrusting on the crest of a fault-propagation fold formed on the west-verging roof thrust. Uplift that exposes the Coast Range ophiolite in the East Bay Hills is formed by oblique thrusting generated by slip transfer at the northern termination of the Calaveras fault. The Paleogene extensional fault system likely extends farther west than previously documented. An east-dipping branch of that system may underlie the Walnut Creek Valley. Three-dimensional restoration should be applied to constrain geologic frameworks to be used for seismic velocity modeling.
- anticlines
- basement
- basin analysis
- California
- Cenozoic
- Coast Ranges
- Contra Costa County California
- contraction
- decollement
- earthquakes
- extension faults
- faults
- folds
- Franciscan Complex
- grabens
- Great Valley Sequence
- Hayward Fault
- Mesozoic
- Miocene
- Neogene
- Paleogene
- Pleistocene
- Pliocene
- Quaternary
- San Francisco Bay region
- strike-slip faults
- structural analysis
- systems
- tectonics
- Tertiary
- three-dimensional models
- thrust faults
- United States
- Walnut Creek
- well logs
- Mount Diablo
- Las Positas Fault
- Rio Vista California
- Benicia California
- Altamont Ridge