Structural analysis of late Neogene deformation in the central offshore Santa Maria Basin, California

Journal Article · Wed Apr 10 04:00:00 EDT 1991 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/90JB00922· OSTI ID:5446989

Clark, D H; Hall, N T; Hamilton, D H ^[1]; Heck, R G ^[2]

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1. Earth Sciences Associates, Palo Alto, CA (USA)
2. R.G. Heck and Associates, Carpinteria, CA (USA)

Structural analysis of the Queenie structure, a topographically prominent, southwest vergent asymmetric fold located 35 km west of Point Sal, constrains the timing and nature of late Neogene deformation in a transect across the central offshore Santa Maria Basin. Analysis of post-Miocene sediments mantling the fold indicates that the Queenie structure was formed in a relatively brief episode of NE-SW directed shortening between 5 and 3 Ma, apparently in response to the onset of compression normal to the North American/Pacific plate boundary. Retrodeformation of depth-corrected cross sections constructed from an extensive set of common depth point seismic data demonstrates that the Queenie structure overprints a Miocene extensional basin and is a fault propagation fold that formed as compression changed the normal slip on the basin margin shear zone to reverse slip. Geometric constraints and seismic data suggest that the controlling shear zone dips moderately (30{degrees} to 50{degrees}) to the northeast and is essentially nonlistric to the base of the brittle crust at a depth of about 12 km. Structural analysis of cross sections further shows that average total post-Miocene NE-SW shortening across the Queenie structure is about 3% (0.39 km across the 130km-wide zone of folding) and that related shortening across the 40-km-wide central reach of the offshore Santa Maria Basin between the Hosgri fault and the Santa Lucia Bank fault during the same period is roughly 1-2% (0.4-0.8 km). High-resolution seismic reflection data show small folds in post-early/late Pliocene sediments on the southwestern flank of the Queenie structure. These folds exhibit minor coaxial deformation along the flank of the structure, suggesting that very low rates of tectonic folding (of the order of 0.005 mm shortening per year) may continue to the present.

• OSTI ID: 5446989
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 96:B4; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
AGE ESTIMATION
CALIFORNIA
CENOZOIC ERA
COMPRESSION
DEFORMATION
DEVELOPED COUNTRIES
FEDERAL REGION IX
GEOLOGIC AGES
GEOLOGIC FAULTS
GEOLOGIC FORMATIONS
GEOLOGIC FRACTURES
GEOLOGIC HISTORY
GEOLOGIC STRATA
GEOLOGIC STRUCTURES
GEOLOGY
GEOMORPHOLOGY
GEOPHYSICAL SURVEYS
INCLINED STRATA
NORTH AMERICA
OFFSHORE SITES
OPTICAL PROPERTIES
ORIGIN
PHYSICAL PROPERTIES
REFLECTIVITY
SEDIMENTARY BASINS
SEDIMENTS
SEISMIC SURVEYS
SLIP
SURFACE PROPERTIES
SURVEYS
TECTONICS
TERTIARY PERIOD
USA