Masters Thesis

Provenance study of the Kern River formation, within the Kern River oilfield, using detrital zircon geochronology

Two competing hypotheses suggest different directions of fluvial transport during deposition of the late Miocene Kern River Formation. The first proposes that the Kern River Formation was deposited by west-flowing channels of the Kern River and the second by northwest flowing channels of the Caliente River. This project seeks to determine the provenance of fluvial sand reservoirs within the Kern River Formation by using geochronology, two and three dimensional resistivity amplitude modeling and spatial analysis of pluton-ages within watershed models. This study concludes that the provenance of Kern River Formation, within the Kern River oil field, is from the southeastern Sierra Nevada and Tehachapi Mountains and that sediments were transported primarily by the Caliente River. U-Pb detrital zircon analysis of twenty-four core and outcrop samples using LA-ICP-MS was used to determine provenance ages. Twenty-one samples show U-Pb ages similar to those reported for the Caliente River depositional system and support a provenance history from the Caliente Creek watershed. Three samples suggest intermittent deposition from Poso Creek or proto-Lower Kern River watersheds on the eastern and northern edges of the study area. This interpretation is consistent with published detrital U-Pb data for recent Caliente Creek and Kern River deposits. Two dimensional resistivity-amplitude mapping was used to show channel orientations. Three dimensional volumetric resistivity-amplitude modeling was used to build maps of gross interval thickness and net sand thickness between upper and lower age constraint stratigraphic markers. Two braidplains observed in resistivity maps, show a north-northwest and a west-southwest orientation. The north-northwest braidplain suggests a Caliente Creek depositional system. The net sand map shows that net-sand thickness decreases to the northeast, reinforcing evidence for a north-northwest flowing depositional system. This data shows that the Miocene Kern River Formation was primarily deposited by the Caliente River and not from the Kern River. Therefore stream capture and development of the modern drainage did not occur until after late Miocene time.

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