Marine deep seismic reflection profiles off central California

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

DOI:https://doi.org/10.1029/90JB00493· OSTI ID:5446996

Ewing, J ^[1]; Talwani, M ^[2]

---

1. Woods Hole Oceanographic Institution, MA (USA) Houston Advanced Research Center, The Woodlands, TX (USA)
2. Rice Univ. Houston, TX (USA) Houston Advanced Research Center, The Woodlands, TX (USA)

A strong reflection horizon at two-way travel time of approximately 6 s is observed in a deep seismic profile across the outer continental shelf of central California. It is interpreted as the seismic image of subducted oceanic crust emplaced prior to the change from principally convergent to principally transcurrent motion between the Pacific and North American plates during the late Paleogene. The reflector dips landward at a very shallow angle and is at a depth of 14-15 km under Santa Lucia Bank. The reflection is not observed, or at best is very discontinuous, under the inner shelf (Santa Maria Basin). This suggests that tectonic or other processes have produced significantly different structural styles or compositions on the two sides of the Santa Lucia Bank fault. Under the outer shelf a prominent, apparently deeper (later arrival time) horizon dips more steeply and diverges from the 6-s reflector. The deep horizon is at least partially composed of diffracted energy but is nearly linear after migration. Possible interpretations are that the horizon indicates crustal imbrication or out-of-plane diffractions. Alternatively, it is a relict feature imparted to the crust at the now inactive Pacific-Farallon spreading ridge. Reflective zones at intermediate depths are observed in apparently accreted sediments in parts of the Santa Lucia and Santa Maria basins. These features could represent tectonically induced fabrics within the accretionary complex, or they could be coherent depositional sequences.

• OSTI ID: 5446996
• 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
CALIFORNIA
CENOZOIC ERA
CONTINENTAL MARGIN
CONTINENTAL SHELF
DATA ACQUISITION
DEPTH
DEVELOPED COUNTRIES
DIMENSIONS
EARTH CRUST
FEDERAL REGION IX
GEOLOGIC AGES
GEOLOGIC FAULTS
GEOLOGIC FRACTURES
GEOLOGIC MODELS
GEOLOGIC STRATA
GEOLOGIC STRUCTURES
GEOPHYSICAL SURVEYS
INCLINED STRATA
NORTH AMERICA
OCEANIC CRUST
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
PLATE TECTONICS
REFLECTIVITY
SEISMIC SURVEYS
SURFACE PROPERTIES
SURVEYS
TECTONICS
TERTIARY PERIOD
USA