Geology of the Nodular Shale of the Middle and Upper Miocene of the Western Los Angeles Basin

Citation

Tovell, Walter Massey (1942) Geology of the Nodular Shale of the Middle and Upper Miocene of the Western Los Angeles Basin. Master's thesis, California Institute of Technology. doi:10.7907/Q7TF-MP08. https://resolver.caltech.edu/CaltechTHESIS:03182010-090316876

Abstract

Investigations of the Geology of the Nodular Shale were carried on under the auspices of the Standard Oil Company of California. Attempts were made to arrive at some conclusions with regard to the origin of the Nodular Shale, and its relationship to the origin of Petroleum that occurs below it in several fields of the West Los Angeles Basin.

The Nodular Shale is Middle Miocene in age in the southern part of the West Los Angeles Basin, and Upper Miocene in the Northern part. It is suggested that the Nodular was laid down in seas transgressing from south to north, and that an ancestral Santa Monica Mountains formed a barrier to this transgressing sea, as evidenced by the heavy mineral content of the Nodular Shale. The Nodular Shale is folded in the areas of the Oil Fields in which it occurs, and this folding is thought to have affected the Schist surface as well. It has also been affected by faulting.

The Nodular Shale is considered to have been the source beds for most of the petroleum in the reservoir rocks that lie below it in the Playa Del Rey and El Segundo Oil Fields.

Several areas are considered to be favorable locations for new petroleum discoveries in the region studies.

It is possible that the Murray-Reynard theory for the deposition of phosphatic nodules, is applicable to the conditions that prevailed in the West Los Angeles Basin area, and that the nodules of the Nodular Shale are the result of seasonal variations of temperature in the Nodular sea, with a consequent periodic dying off of large portions of the fauna that inhabited the seas of that time.

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