Budget of postrifting sediments in the Gulf of California and calculation of the denudation rate in neighboring land areas.

Abstract

Using seismic records and porosity-depth curves, we calculate the volume of 'dry' post-rifting sediment in the 4-m.y.-old central and S Gulf of California to be approximately 12 500 km3. For an area of 127 000 km2, this volume represents a mean sedimentation rate of 2.5 cm/ky. for dry, solid material. Postrifting sediments on the proto-Gulf shelves (65 000 km2) may fill a 15 000 km3 volume (a mean sedimentation rate of 5.8 cm/ky. for dry, solid material). From the input of terrigenous material, the mean denudation rate of the drainage area (271 500 km2) of the S and central Gulf has been approximately 2cm/ky. for the last 4 m.y. This rate is lower than most denudation rates that have been determined from sediment-load measurements for river basins with similar climates and relief. The characteristics of the drainage basin under study and causes for this discrepancy are discussed. -from Authors