Deep crustal structure and tectonics in the offshore southern Santa Maria Basin, California

Journal Article · Sat Feb 29 23:00:00 EST 1992 · Geology; (United States)

DOI:https://doi.org/10.1130/0091-7613(1992)020<0239:DCSATI>2.3.CO;2· OSTI ID:6951933

Nicholson, C; Sorlien, C C; Luyendyk, B P ^[1]

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1. Univ. of California, Santa Barbara (United States)

Reprocessed deep-penetration seismic reflection profiles across the offshore southern Santa Maria Basin suggest a complex history of tectonic deformation. The top of subducted oceanic crust, imaged at the north end of EDGE line RU-10, is disrupted and eventually disappears to the south. Farther south, a strong lower crustal reflection ramps up and may reflect a possible north-dipping low-angle detachment, or a change in crustal geometry associated with the subducted Morro Fracture Zone. Above a time-transgressive unconformity, Miocene and younger sediments onlap to the south and water bottom deepens, suggesting a major regional tilt reversal in post-Miocene time. Below the unconformity, basement is displaced by largely northwest-striking normal faults that the authors believe form tilted crustal blocks; it is possible that Cretaceous and Paleogene sections are preserved in resulting half-grabens. Some of these normal faults, including splays off the outer Santa Lucia Bank fault system, were reactivated as minor reverse faults in post-Miocene time. There is no evidence that requires any post-17.5 Ma tectonostratigraphic terrane boundary through this area; rather, much of the structure of the southern Santa Maria Basin appears to be continuous with the rotated Western Transverse Ranges and northern Channel Islands.

• OSTI ID: 6951933
• Journal Information: Geology; (United States), Journal Name: Geology; (United States) Vol. 20:3; ISSN GLGYB; ISSN 0091-7613
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
BASEMENT ROCK
CALIFORNIA
CENOZOIC ERA
CRETACEOUS PERIOD
DEVELOPED COUNTRIES
GEOLOGIC AGES
GEOLOGIC FAULTS
GEOLOGIC FRACTURES
GEOLOGIC HISTORY
GEOLOGIC STRATA
GEOLOGIC STRUCTURES
GEOPHYSICAL SURVEYS
INCLINED STRATA
MESOZOIC ERA
NORTH AMERICA
OFFSHORE SITES
SEDIMENTARY BASINS
SEISMIC SURVEYS
SUBDUCTION ZONES
SURVEYS
TECTONICS
TERTIARY PERIOD
USA