Paleocene Benthonic Foraminiferal Biostratigraphy of the Eastern Gulf Coastal Plain

Abstract

The Paleocene strata of eastern and central Alabama and western Georgia are rich in well preserved benthonic foraminifera but relatively poor in well preserved planktonic foraminifera. The portions of the Paleocene section lacking planktonic foraminifera can be integrated into the global geochronologic time scale through the use of benthonic foraminiferal assemblages. A paleontological analysis of benthonic foraminifera on 154 samples selected from the Eastern Gulf Coastal Plain provided the basis of a chronostratigraphic framework. Four biozones were defined: the Eponides elevatus Zone (= Zone Plb), the Alabamina midwayana Zone (= Zone Plc through lower P4), the Discorbis washburni Zone (= middle Zone P4) and the Alabamina westraliensis Zone (= upper Zone P4 through P6a). The use of benthonic foraminifera in local correlation is an effective tool, particularly in the case of surface and subsurface sections which have undergone diagenetic changes and do not contain well preserved planktonic microfossils. We anticipate that this biostratigraphic zonation may be effectively applied to other units of the Mississippi Embayment and the Gulf Coastal Plain.