Compressional- wave velocities in basalts from the Rio Grande Rise ( DSDP, Leg 72).

Abstract

Compressional-wave velocities were measured in 9 samples from the 18 m of igneous basement penetrated by drilling at Hole 516F. Velocities in basalts from immediately beneath the sediment/basement contact are consistent with the proposed age (86+ or -4 Ma) of basement at the site. A very strong vertical velocity gradient of 0.126 km/s/m in the 18-m basement interval reflects a marked decrease in the degree of alteration with depth beneath the contact.-from Authors