Foraminiferal Ratios and Regional Environments

Abstract

ABSTRACT A simple, easily obtained ratio of planktonic/benthonic foraminiferal is shown to yield a considerable amount of geologic information. The utility of the ratio is demonstrated by application to an interpretation of regional environments in Upper Cretaceous strata in East Texas, southern Arkansas, and northern Louisiana. Planktonic/benthonic ratios plotted against stratigraphic horizon in the form of a well log appear to reveal the developmental history of barriers to oceanic circulation. Contoured ratio values for the Upper Cretaceous rocks studied show relationships to structural and lithofacies patterns. The contoured ratio surfaces indicate the general patterns of oceanic circulation in the study area during the Late Cretaceous and their change with time.