About This Item

Share This Item

The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract


Volume: 34 (1950)

Issue: 12. (December)

First Page: 2384

Last Page: 2384

Title: Southern Coastal Region: ABSTRACT

Author(s): Gordon B. Oakeshott

Article Type: Meeting abstract

Abstract:

The Southern Coastal region is here defined as a narrow coastal strip of sedimentary deposits extending from the vicinity of San Onofre on the north to the Mexican border on the south and from the Pacific Ocean to outcropping crystalline rocks in the Peninsular Range a few miles east. The northern part of the region is a southeastward extension of the Lost Angeles basin; the southern part of the region is the San Diego Plio-Pleistocene basin. The coastal sedimentary strip connecting the two basins is occupied by an Eocene series overlying Cretaceous sediments at shallow depth. The total area of sedimentary rocks is approximately 950 square miles and maximum depth to basement is probably not much more than 6,000 feet.

Structurally, the sedimentary strip comprising the Southern Coastal region is relatively simple; it has not been subjected to intense folding or faulting. Cretaceous and Eocene sediments dip gently westward off the older crystalline rocks making up the Peninsular Ranges and are overlain by middle Miocene San Onofre sediments in the northern part of the area, and by middle Pliocene San Diego sediments in the vicinity of San Diego. Unconformities between formations exist, but there are no great angular unconformities and formations from the Upper Cretaceous Chico to middle Pliocene San Diego are almost concordant. The northwest-trending Soledad Mountain anticline, near La Jolla, is a local exception to the simple regional structure.

The Southern Coastal region lacks the seepages of oil and gas so common in petroliferous regions elsewhere in California. More than 30 wildcat wells, several of which reached basement, have been drilled in the region without shows of oil or gas. The Soledad Mountain anticline has been tested by several wells and depth to basement at the crest of that structure has been shown to be about 3,750 feet.

End_of_Article - Last_Page 2384------------

Copyright 1997 American Association of Petroleum Geologists