This collaborative project will study the structural and stratigraphic evolution of the Pliocene-Quaternary Loreto Basin, which lies along the margin of the Gulf of California in Baja California Sur. A transform-rift system beginning at 5Ma formed the Loreto and related basins but they have not been studied in detail until now, despite good exposure and accessibility. Magnetostratigraphy will be combined with radiometric dating of four tuffs and paleontological data of other workers to give good chronostratigraphic control of the basin's evolution. These data will permit investigation of the role of growth structures on the stratigraphic geometries in the basin. The results will resolve major outstanding problems in the tectonics of the Gulf of California, and will have important implications for the tectonics of obliquely-rifted margins in general.
