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The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract


Volume: 51 (1967)

Issue: 3. (March)

First Page: 474

Last Page: 475

Title: Paleoecology of Santa Barbara Zone, Pliocene of Southern California: ABSTRACT

Author(s): Robert F. Meade

Article Type: Meeting abstract

Abstract:

The Santa Barbara fauna is used to define a widespread zone in the Plio-Pleistocene rocks of the Ventura basin. This fauna is characterized by extinct, northern extra-limited, and submergent species of Mollusca. The characteristic species are accompanied by some locally extant species.

A section of the Fernando Formation exposed in Balcom Canyon in the central Ventura basin is composed of rocks deposited in water depths greater than 100 fathoms. Turbidite sandstones contain fossil Mollusca derived from all depth zones, from the depth of deposition on up to the intertidal. These mixed faunas were separated into depth associations on the basis of the depth ranges of living members of the faunas and on apparent associations in the faunas. The characteristic

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species of the Santa Barbara fauna are generally part of an association that lived in the deep-inner to shallow-outer sub-littoral depth zones (15-50 fathoms).

The lower part of the section studied contains fossils from the same depth zone as the Santa Barbara fauna. These fossils indicate that water temperatures were not detectably different than at present. The upper part of the section contains the Santa Barbara fauna, which indicates that waters at these depths were considerably colder in this region than at present. Most of the characteristic extra-limited species do not range south of Puget Sound. Associated with the characteristic species are others that do not live that far north today. This association of species not now living together must indicate either that the temperature tolerances of some have changed or that their distributions are controlled by some factor other than mean annual temperature.

The upper part of the section also contains numerous mollusks that lived in shallower water. The present distributions of extant members of these faunas indicate water temperatures not detectably different from temperatures today.

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Copyright 1997 American Association of Petroleum Geologists