Interpretations of Gravity Data from the Central Coast Ranges and San Joaquin Valley, California

Abstract

A Bouguer anomaly profile across the Central Coast Ranges and San Joaquin Valley of California has been corrected for the effects of local suprabasement mass deficiencies. The profile extends approximately from Lucia to King City to Madera. Negative Bouguer anomalies of several tens of milligals are associated with the Tertiary sedimentary basins of the Coast Ranges and can be accounted for both from their limited extent and from available density data. The Joaquin Ridge serpentine body is apparently entirely serpentine, with no underlying unaltered ultramafic rock. Models can be constructed which suggest that the Diablo Range, at this latitude, is more or less isostatically compensated. However, isostatic modeling calculations, based upon anomalies of a few tens of milligals, approach the limits of meaningful evaluation of the models.