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Chronostratigraphic Significance of Late Cenozoic Planktonic Foraminifera from Ventura Basin, California: Implications for Depositional History, Tectonic Reconstruction, and Exploration for Bathyal Clastic Reservoirs

Martin B. Lagoe, Peter R. Thompson

A chronostratigraphic framework for the late Cenozoic borderland basins of central and southern California is compiled from evolutionary datums of temperate North Pacific planktonic foraminifera and paleoclimatically controlled coiling shifts in Neogloboquadrina pachyderma. All datums are calibrated against paleomagnetic and tephra stratigraphies, as well as established global time scales. The chronostratigraphic framework is applied to three key sections from the Ventura basin: Wheeler Canyon (containing the stratotypes for the Venturian and Wheelerian stages), Santa Paula Creek, and Balcom Canyon. Improved chronostratigraphic correlations are demonstrated for the interval between 0.6 and 3.0 Ma. Because borderland basins along this active continental margin contain thic , stratigraphically complex accumulations of basin fill, accurate and high-resolution chronostratigraphic correlations are needed to better reconstruct the depositional and paleoenvironmental history of this area. In addition, stratigraphic trapping of hydrocarbons in bathyal clastic reservoirs is a prominent feature in these borderland basins. Exploration strategies for these areas can be greatly improved by applying the proposed chronostratigraphic correlations to stratigraphic mapping on selected time horizons, development of improved depositional models, and better reconstructions of bathymetric and tectonic history. A geohistory plot for the central Ventura basin illustrates some of the benefits of the proposed chronostratigraphic framework by documenting and constraining the timing of two episodes of basin subsidence during the Pliocene-Pleistocene.

AAPG Search and Discovery Article #91038©1987 AAPG Annual Convention, Los Angeles, California, June 7-10, 1987.