Magnetostratigraphy of Neogene Sedimentary Sequences in California

VEROSUB, KENNETH L., University of California, Davis, CA

Neogene sedimentary sequences account for a significant percentage of hydrocarbon production in California. Because of facies variations and the endemic nature of the fauna, the dating of several important formations and the correlation of sequences within these formations have been difficult. In the Paleomagnetism Laboratory of the University of California-Davis, magnetostratigraphy has been used successfully to resolve some of these problems. For example, a study of the sedimentary rocks of the Ridge basin in southern California has provided a detailed chronostratigraphic framework for sedimentologic and geochemical studies as well as new information about tectonic processes and rates of sedimentation. A similar study of the sedimentary rocks of the Purisima Formation of central Cal fornia has led to the determination of the duration of a major unconformity, to the correlation of a nearshore sequence with its deeper water equivalent, and to the recognition of over 50 degrees of tectonic rotation in the last 2.5 m.y. Work now in progress on the Etchegoin and San Joaquin formations should help to overcome chronostratigraphic problems with these sequences that have not been solved by traditional geologic techniques.

AAPG Search and Discovery Article #91004 © 1991 AAPG Annual Convention Dallas, Texas, April 7-10, 1991 (2009)