Geologic framework of Mount Diablo, California

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The basic stratigraphic and structural framework of Mount Diablo is described using a revised geologic map, gravity data, and aeromagnetic data. The mountain is made up of two distinct stratigraphic assemblages representing different depocenters that were juxtaposed by ~20 km of late Pliocene and Quaternary right-lateral offset on the Greenville-Diablo-Concord fault. Both assemblages are composed of Cretaceous and Cenozoic strata overlying a compound basement made up of the Franciscan and Great Valley complexes. The rocks are folded and faulted by late Neogene and Quaternary compressional structures related to both regional plate-boundary–normal compression and a restraining step in the strike-slip fault system. The core of the mountain is made up of uplifted basement rocks. Late Neogene and Quaternary deformation is overprinted on Paleogene extensional deformation that is evidenced at Mount Diablo by significant attenuation in the basement rocks and by an uptilted stepped graben structure on the northeast flank. Retrodeformation of the northeast flank suggests that late Early to early Late Cretaceous strata may have been deposited against and across a steeply west-dipping basement escarpment. The location of the mountain today was a depocenter through the Late Cretaceous and Paleogene and received shallow-marine deposits periodically into the late Miocene. Uplift of the mountain itself happened mostly in the Quaternary.

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Publication type Book chapter
Publication Subtype Book Chapter
Title Geologic framework of Mount Diablo, California
DOI 10.1130/2021.1217(01)
Volume 217
Year Published 2021
Language English
Publisher Geological Society of America
Contributing office(s) Geology, Minerals, Energy, and Geophysics Science Center
Description 34 p.
Larger Work Type Book
Larger Work Subtype Monograph
Larger Work Title Regional geology of Mount Diablo, California: Its tectonic evolution on the North America plate boundary
First page 1
Last page 34
Country United States
State California
Other Geospatial Mount Diablo
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