The Calcareous Nannoplankton of the Midway Group (Paleocene) of Alabama

Abstract

The calcareous nannoplankton in samples from the Paleocene Midway group of Alabama were examined and photographed using both a light misroscope and a scanning electron miscroscope. Twenty-seven species were identified, two of which are described as new. The nannoplankton distribution was used to correlate the Alabama Midway Group with standard Paleocene nannoplankton zonations resulting in the Pine Barren and McBryde members of the Clayton Formation being assigned to the Cruciplacolithus tenuis zone, and the Porters Creek Clay and the Matthews Landing Member being assigned to the Cyclococcolithina robusta zone. The nannoplankton distribution and abundances are related to the lithology and depositional environments of the Midway units. The Clayton and Porters Creek units contain certain species that are confined to or are more abundant in, particular lithologic facies. The very shallow water deposits of the Naheola Formation are barren of nannoplankton.