Tectonic Elements of the Northern Part of the Gulf of California

Abstract

Results from a continuous seismic survey along closely spaced ship tracks in the northern Gulf of California are presented in terms of the tectonics of this region. Apparent vertical offsets of the most recent sediments, ranging in height from several to a few hundred meters, are associated with the central basins (Delfin and Wagner basins), indicating they are the loci of active tectonism. Structural relations inferred from mapping these features are consistent with plate tectonic concepts of the Gulf. Delfin basin represents a single, complex, northeast-southwest–trending, spreading center. Two parallel transform faults, which flank Angel de la Guarda Island and strike northward into Delfin basin from the south, and a complementary transform fault to the north represented by the Wagner basins, end at this spreading center. With the possible exception of the San Jacinto fault, no correlation of active faults was found between the northern Gulf and contiguous land areas. Interpretations of other geophysical and geological data are complicated by the high sedimentation rate in the northern Gulf, yet are generally consistent with our conclusions. Spatial and temporal characteristics of plate boundaries in the northern Gulf are probably influenced by the proximity of continental structures.