Pre-transform early Miocene extension in western California
- Geological Survey, Denver, CO (USA)
Earliest Miocene (20-24 Ma) faulting and volcanism were widespread in western California, including the San Joaquin-La Honda basin, Coast Ranges, and Transverse Ranges. Evidence for strike slip on faults of this age is lacing. Their arrangement on a pre-San Andreas restoration suggest continuity with early Miocene extended terranes in eastern California and southwestern Arizona. Deformation was probably not an effect of transform or triple-junction-migration tectonics, because it was synchronous over 300 km of latitude and there is no direct evidence for a transform boundary until late in early Miocene time. Magnetic anomalies in the eastern Pacific permit an interpretation that a spreading ridge supplied a still-active subduction zone with young oceanic crust until sometime after 20 Ma. If so, extension evidently took place in an arc-related setting. A transform regime probably formed about 18 Ma, when most basins underwent episodes of deepening or uplift, strike-slip faults became active, and rotation of the western Transverse Ranges block began.
- OSTI ID:
- 6852369
- Journal Information:
- Geology; (USA), Journal Name: Geology; (USA) Vol. 17:9; ISSN GLGYB; ISSN 0091-7613
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
580000* -- Geosciences
AGE ESTIMATION
ARIZONA
CALIFORNIA
CENOZOIC ERA
DEFORMATION
FEDERAL REGION IX
GEOLOGIC AGES
GEOLOGIC FAULTS
GEOLOGIC FRACTURES
GEOLOGIC HISTORY
GEOLOGIC STRUCTURES
GEOPHYSICAL SURVEYS
MAGNETIC SURVEYS
MIOCENE EPOCH
MOTION
NORTH AMERICA
PLATE TECTONICS
ROTATION
SUBDUCTION ZONES
SURVEYS
TECTONICS
TERTIARY PERIOD
USA
VOLCANISM