Abstract
Coastal southern California is east of the Darwin Rise and west of the East Pacific Rise. Accordingly, southern California structural history has implications regarding Pacific Ocean Basin history, particularly the age and nature of the Darwin and East Pacific Rises and the Murray fracture zone, using the sea-floor-spreading model. The Darwin Rise is related to the Franciscan and has a minimum age range of Jurassic to early Late Cretaceous. The Murray fracture zone can be dated through paleogeographic reconstruction of the Late Cretaceous-Early Tertiary coastal sequence; it formed later than Maestrichtian, but no later than middle Eocene time. During the Miocene, the East Pacific Rise moved eastward under the Coast Ranges at a rate of 5.6 cm/yr, producing volcanism and rift topography as it passed, and reaching the site of the Gulf of California in latest Miocene time.
