Interpretation of continuous-offset seismic data in central California margin
As part of the Pacific Gas and Electric deep crustal geophysical survey, 154 seismic group recorders were deployed in a linear, fixed receiver array to record three one-ton land dynamite shots and 406 10,280-in./sup 3/ air gun pops. Receivers were deployed every 350 m in a 50-km line extending to the northeast from the coast at Morro Bay, California. The receivers cross the Sur-Obispo terrane, the Macimiento and Rinconada fault zones, and part of the sediment-covered Salinian block. A seismic vessel fired the air gun array from 2.4 to 65.5 km offshore at 155-m intervals in line with the onshore receiver spread. The sources extended across the Hosgri fault zone and the Santa Maria basin. The authors have produced a reflection image at 5.5 to 6.0 sec two-way traveltime by CMP stacking traces with offsets less than 20 km. They believe this event, which is at about 14-km depth and dips landward at 10/sup 0/-15/sup 0/, is the top of the lower crust. An event that appears on common shot and receiver gathers, they interpret as a wide-angle reflection from the base of this dipping lower crustal layer. Ray tracing of receiver gather refraction records indicates that the layer flattens seaward of the coast. They believe that this feature is a remnant of oceanic crust that had been subducting beneath the Mesozoic-Cenozoic California margin and is tectonically correlative with a bright continuous event found on nearby offshore reflection profiles at about 6 sec two-way traveltime.
- Research Organization:
- Rice Univ., Houston, TX (USA)
- OSTI ID:
- 6639249
- Report Number(s):
- CONF-8804144-
- Journal Information:
- AAPG Bull.; (United States), Vol. 72:3; Conference: AAPG SEPM-SEG Pacific Section and SPWLA annual convention, Santa Barbara, CA, USA, 17 Apr 1988
- Country of Publication:
- United States
- Language:
- English
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