Structural deformation in the offshore Santa Maria basin, California

The authors divide the offshore Santa Maria basin into the southern, central, and northern provinces based on the pattern, style, and timing of late Cenozoic deformation. From their analyses of over 2,000 km of CDP seismic data and offshore well data they prepared time structure contour maps for three basin-wide unconformities: top of basement, top of Miocene, and the unconformity between early and late Pliocene chronostratigraphic units. Isochron maps were constructed between these horizons and between the early/late Pliocene unconformity and the sea floor to evaluate timing of the deformation. All maps were converted to depth and isopach values based on a three-dimensional velocity model. The regional structure contour and isopach maps show that the offshore Santa Maria basin is characterized by localized crustal shortening orthogonal to the Pacific/North America plate margin and indications of post-Miocene to recent lateral slip along the eastern basin boundary, the San Simeon/Hosgri fault system.