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Download or read book Structural Evolution of the Carpinteria Basin, Western Transverse Ranges, California written by Patrick A. Jackson and published by . This book was released on 1981 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Pleistocene Carpinteria basin is an east-trending northward-verging, faulted syncline containing up to 1220m of partially intertonguing Santa Barbara and Casitas Formations deposited on previously folded pre- Pleistocene strata with up to 80° discordance. Structures subcropping against the unconformity indicate most of the deformation in the Santa Ynez Range prior to deposition of the Santa Barbara Formation approximately one Ma ago was by folding. During that time, the Carpinteria area was the northern margin of the offshore Ventura basin; subsequent uplift north of the Red Mountain fault (RMF) isolated the Carpinteria basin during middle to late Pleistocene time. Quaternary faults in the area are either south-dipping reverse faults related to bedding-slip in pre- Pleistocene strata or north-dipping reverse faults that truncate bedding and are seismically active. The Rincon Creek fault (RCF) dips 35°-60° south steepening to near-vertical at depth, where it apparently passes into bedding within the upper Sespe Formation. It offsets late Pleistocene marine terraces and is itself deformed by the RMF. The RMF dips 55°-63° north at the surface and steepens to 75° north with depth; and also steepens westward south of the Summerland Offshore oil field to 85° north. Vertical separation decreases westward from 4500m north of the Rincon field to 350m at Rincon Point. The main branch of the RMF offsets a 45,000yr marine terrace, but not a 4,500yr terrace. The Summerland Offshore oil field occurs within a disharmonically folded anticline in which incompetent, severely deformed Miocene mudstone overlies competent, broadly folded Oligocene sandstone. Because the anticline formed after deposition of the Santa Barbara Formation, the age of oil migration into the field was post-Santa Barbara during middle to late Pleistocene time.