Eocene Stratigraphy of Chico Martinez Creek Area, Kern County, California

Abstract

Although the geology of the Chico Martinez Creek area has been studied several times since 1905, the Oligo-Miocene beds have received the most attention, and the Eocene strata have been virtually ignored. The purpose of the present study is to record the detailed stratigraphy and paleontology of these Eocene strata immediately subjacent to the Zemorrian stage at its type locality. Three faults and two folds of importance are mapped. Ecologic analyses of the foraminiferal assemblages of Zemorra Creek suggest that the formation was deposited in the open sea at or below the edge of the continental shelf and at a latitude where surface waters were tropical or sub-tropical. Rapid accumulation of detritus on a steeply sloping bottom profile is also indicated. Comparison of check lists of Foraminifera shows that members 1, 2, and the upper part of member 3 of the formation of Zemorra Creek are probably equivalent in age to the Sagasar shale member of the Kreyenhagen formation of Reef Ridge and that the lower part of member 3 and members 4, 5, 6, and 7 are probably equivalent to the Canoas siltstone member. Thus, while siliceous shales were being deposited in the Reef Ridge district, coarse sandstones were being deposited in the Chico Martinez Creek-Carneros Creek region. Attempted correlation with the type Tejon formation and the type Devil's Den shale was unsuccessful.