25. Sediment Velocities and Deep Structure from Wide-angle Reflection Data around Leg 116 Sites
نویسندگان
چکیده
The reduction of six wide-angle reflection profiles shot within the two fault blocks visited by Ocean Drilling Program (ODP) Leg 116 in combination with the ODP sonic logs has produced a velocity-depth structure for this area. The sediment velocity increases from 1.6-1.7 km/s in the near surface to 3.4-3.5 km/s immediately above basement with a velocity gradient of 0.75/s. A depth converted seismic reflection profile suggests that the pre-deformational basement surface was similar to the abyssal hill topography developed in the Pacific Ocean. A velocity for the top of oceanic layer 2 of 4.1 km/s was identified as layer 2A. Assuming a velocity gradient of 0.7/s, an estimate of layer 2 thickness was obtained of 1.5 km. It is possible to interpret residual depth anomalies in terms of a layer 3 that may be thinner than for normal oceanic crust.
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