Velocity of deep-sea sediments from sonobuoy data

Interval velocity solutions from sonobuoy data reveal three major sedimentary sequences: (1) Unconsolidated sediments whose velocity increases with depth of burial and ranges from 1.6 to 2.2 km/sec; (2) semiconsolidated sediments (layer A), which probably have some velocity discontinuities, whose velocity increases with depth of burial and ranges from 1.7 to 2.9 km/sec; (3) consolidated sediments (layer β), measured in a few places, whose velocity is apparently independent of overburden and ranges from 2.7 to 3.7 km/sec. In the shallower layers, low velocities seem to be related to the deposition of clay-sized particles by relatively swift bottom currents; high velocities, to quieter bottom conditions or the influx of much turbidite material. Except for the shallow layers, velocity-depth functions are quite similar for the Gulf of Mexico and the Atlantic Ocean. All the curves show an increase of velocity with depth without significant velocity reversals.

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