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

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.
Mid-Cenozoic succession on the northeast limb of the Mount Diablo anticline, California—A stratigraphic record of tectonic events in the forearc basin Available to Purchase
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Published:September 27, 2021
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CiteCitation
Raymond Sullivan, Morgan D. Sullivan, Stephen W. Edwards, Andrei M. Sarna-Wojcicki, Rebecca A. Hackworth, Alan L. Deino, 2021. "Mid-Cenozoic succession on the northeast limb of the Mount Diablo anticline, California—A stratigraphic record of tectonic events in the forearc basin", 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
The mid-Cenozoic succession in the northeast limb of the Mount Diablo anticline records the evolution of plate interactions at the leading edge of the North America plate. Subduction of the Kula plate and later Farallon plate beneath the North America plate created a marine forearc basin that existed from late Mesozoic to mid-Cenozoic times. In the early Cenozoic, extension on north-south faults formed a graben depocenter on the west side of the basin. Deposition of the Markley Formation of middle to late? Eocene age took place in the late stages of the marine forearc basin. In the Oligocene, the marine forearc basin changed to a primarily nonmarine basin, and the depocenter of the basin shifted eastward of the Midland fault to a south-central location for the remainder of the Cenozoic. The causes of these changes may have included slowing in the rate of subduction, resulting in slowing subsidence, and they might also have been related to the initiation of transform motion far to the south. Two unconformities in the mid-Cenozoic succession record the changing events on the plate boundary. The first hiatus is between the Markley Formation and the overlying Kirker Formation of Oligocene age. The succession above the unconformity records the widespread appearance of nonmarine rocks and the first abundant appearance of silicic volcanic detritus due to slab rollback, which reversed the northeastward migration of the volcanic arc to a more proximal location. A second regional unconformity separates the Kirker/Valley Springs formations from the overlying Cierbo/Mehrten formations of late Miocene age. This late Miocene unconformity may reflect readjustment of stresses in the North America plate that occurred when subduction was replaced by transform motion at the plate boundary. The Cierbo and Neroly formations above the unconformity contain abundant andesitic detritus due to proto-Cascade volcanism. In the late Cenozoic, the northward-migrating triple junction produced volcanic eruptive centers in the Coast Ranges. Tephra from these local sources produced time markers in the late Cenozoic succession.
- age
- basins
- California
- Cenozoic
- Coast Ranges
- Contra Costa County California
- depositional environment
- Eocene
- Farallon Plate
- fore-arc basins
- geologic maps
- Kula Plate
- maps
- marine environment
- middle Cenozoic
- middle Eocene
- North American Plate
- Oligocene
- Paleogene
- plate tectonics
- provenance
- Sacramento Basin
- subduction
- succession
- tectonics
- Tertiary
- United States
- upper Cenozoic
- upper Eocene
- Mount Diablo
- Kirker Formation
- Markley Formation
- Sidney Flat Shale Member
- Cierbo Sandstone
- Neroly Sandstone
- Mount Diablo Anticline
- Upper Markley Sandstone Member
- Lower Markley Sandstone Member