Paleomagnetism Tectonic Rotation of the MIOCENE OBISPO Formation, Western Santa Barbara County, CA.

Abstract

This is a paleomagnetic study on the Obispo Formation in the coastal region between Santa Barbara and San Luis Obispo. In this area lies the Santa Maria basin, which contains many faults, including the Santa Ynez fault, the Point Sal fault, and the Lion?s Head fault. The movements of the faults in this region, along with tectonic movement, have caused massive various rotations, and this is what my research focuses on. In early studies of this area it was concluded by Hornafius et al (1985) that there was no rotation in the Santa Maria basin north of the Santa Ynez fault. More recent studies by Khan et all (2001) as well as earlier studies by Greenhaus and Cox (1979) have shown that there is rotation in this area between 30 and 40 degrees. The purpose of my study is to determine two things. Firstly it is to back up the fact that there is rotation in the area. At this point, the research is incomplete and however, we are hoping that we will see rotations of 30 to 40 degrees. Secondly we are trying to determine the age at which the rotation started, which we will be able to report on upon completion of the research. If our hypothesis is correct, we should see rotation as far back as the Obispo formation and possibly even the Lospe formation. If this proves true, we will know that the rotation started during the early Miocene and possibly the late Jurassic, which is during the Gilbert epoch.