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ABSTRACT: An Integrated Neogene Biostratigraphic Framework for Western North America

Gregg H. Blake

Provincial benthic foraminiferal stages and zones constitute the most commonly applied means of biostratigraphic correlation and age dating of Neogene sections along the Pacific Coast. The stages and zones are defined in designated type sections located in several continental margin basins and have been useful tools for intrabasinal and interbasinal correlations.

Calcareous and siliceous planktonic microfossils in these sections have been used to correlate the provincial Neogene stages to deep-sea planktonic zonations and associated geochronologic data. The use of planktonic zonations in conjunction with the benthic foraminiferal stages and zones has provided an improved chronostratigraphic framework for the Neogene sections. However, this framework is based on only second-order or third-order correlations between the sections and the geochronologic time scale.

The increased application of basin modeling, sequence stratigraphic studies, and tectonic reconstructions in California requires accurate age determinations. Therefore it is important that Neogene biostratigraphic zonations be correlated to the geochronologic time scale. Several recent papers have been written on magnetostratigraphic studies, stable isotope age dating, radiochronology, and volcanic event stratigraphy from several Neogene sections in California. Based on these studies, first-order correlations can be made made between the classical Neogene stages of California and the geochronologic time scale. The result is an integrated biostratigraphic and chronostratigraphic framework that can be applied to the Neogene stratigraphic sections of western North America.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990