ABSTRACT

The Santa Barbara Channel region, the westernmost part of the Transverse Range Province, is the submerged offshore extension of the Ventura basin. It is a topographic depression containing more than 15,250 metres of strata ranging in age from Early Cretaceous to Holocene. Core samples reveal that only the Late Neogene sedimentary section is exposed along the El Capitan Gaviota portion of the shelf. This includes the Miocene Monterey Formation, the Late Miocene/Early Pliocene Sisquoc Formation, the Pliocene "Repetto" Formation, the Plio-Pleistocene "Pico" Formation, and Holocene marine sediments.

Continuous seismic surveying investigations show the area to be a continuation of the southward-dipping homoclinal structure of the Santa Ynez Range. Superimposed on this structure are the Molino, Gaviota Offshore, and Elwood Offshore fold trends. Associated with the east--west anticlinal trends are subparallel frontal faults and north--south cross or tear faults. Petroleum development of all three trends has occurred. Folding may have started as early as late Oligocene time with episodic growth through Holocene time. The structure is controlled by a single north--south compressive force with two components of stress, one shallow and one deep in the earth's crust.

Patchy distribution of the unconsolidated overburden sediments is controlled by paleotopography of an erosional bedrock surface. Minor scouring of the unconsolidated material with subsequent redeposition is apparent. During the last twenty years a 1 metre average decrease in overburden cover has occurred.