Abstract: Outcrop Geology of the Central Temblor Range Related to Hydrocarbon Production in the Midway-Sunset Oil Field, Kern County, CA

NILSEN, TOR H.

The Temblor Range is underlain by Upper Cretaceous to Recent strata that record a complex succession of paleogeographic and paleotectonic events. Production from upper Miocene to Pleistocene reservoirs in the adjacent Midway-Sunset Oil Field is largely from clastic units that crop out in the range. The finer grained siliceous members of the Monterey Formation, which include in ascending stratigraphic order the McDonald Shale, Antelope Shale, and Belridge Diatomite, grade upward from chert to opal-CT to opal-A, with the diagenetic boundaries cross-cutting the stratigraphy. These biogenic siliceous members were deposited mostly in deep-marine, restricted conditions; they also contain landslide deposits, debris flows, turbidites, and, locally, hummocky stratified storm deposits. The Crocker Flat Paleolandslide forms a lens of deformed and broken clastic rocks in the McDonald Shale Member. The coarser grained members of the Monterey Formation include in ascending stratigraphic order the Williams Sandstone, Republic Sandstone, Crocker Sandstone, and Santa Margarita Sandstone. The lower three units consist of submarine fans deposited in synclinal lows developed in the siliceous shale members. The Santa Margarita Sandstone Member consists in outcrop of a series of almost equally spaced, generally northeast-trending, submarine-canyon fills that commonly contain granitic boulders and locally overlie or are flanked by diatomaceous paleolandslides. The uppermost outcrop unit and shallowest reservoir, the Tulare Formation, rests with angular unconformity on Miocene units and consists mostly of debris-flow-dominated alluvial-fan deposits shed off the Temblor Range.

Search and Discovery Article #90945©1997 AAPG Pacific Section Meeting, Bakersfield, California