부산대학교 도서관

The Tejor area, located in the southeastern end of the San Joaquin Valley of California, provides an excellent opportunity to study earliest Miocene tectonics and their subsequent control on Miocene deposystems in the east slope setting. Abundant outcrop and subsurface control, correlative time markers (including volcanic units and micropaleontologic reports), and a relatively mild overprinting by recent structuring facilitated this 3-year study. Late Zemorrian through early Saucesian (22 Ma) volcanic flows and eruptives covered the area while coincident tensional faulting caused the Zemorrian-age Vedder shelf-slope system to collapse. A horst-and-graben basin system resulted, with a narrow serrated shelf along the eastern margin. Onset of Saucesian deposition was dominated by conglomeratic turbidites spilling into silled basin depocenters. The clastic load included typical Sierran-derived material and volcanic detritus from the prior flows. Rugged sea floor relief controlled channel courses and sediment thickness. Turbidite deposition continued through the earliest Mohnian. The early Saucesian sea flow topography exerted progressively less effect on channel courses, while influence from previous channel buildups increased. Clastic sorting improved with time as the shelf matured and the slope gradient decreased, and clean reservoir channel sands were deposited in meanderlike patterns. This sequence of events is critical to working the structural and stratigraphic hydrocarbon potential of the Tejon area. Zemorrian Vedder and Eocene-age production is associated with paleohorst blocks (e.g., Tejon North oil field and Tunis Creek pool of the Tejon Hills oil field).