Biostratigraphy of Some Neogene Formations, Northern Florida and Atlantic Coastal Plain: ABSTRACT

Abstract

In recent years worldwide studies by numerous specialists on planktonic Foraminiferida and calcareous nannoplankton have been extended into the type European sections. It is now possible to establish zonations and correlations that appear to be synchronous over long distances, validating, for the first time, the use of European stratigraphic terminology in areas remote from the type localities. The recognition of planktonic microfossils for these purposes is a milestone in Tertiary biostratigraphy, particularly for those who have long found the Lyellian percentage method inadequate as a precise means of determining the age of a Cenozoic formation. The identification of these fossils in the subject areas is also a break-through, because of the significance of many of the sites as type-localities for mollusks, and because of the question of the exact position of these formations in the geologic time scale. Planktonic Foraminiferida and the calcareous nannofossil genera, Discoaster, Catinaster, and Sphenolithus are identified from the subject areas, and the species indicate stratigraphic relations that are at variance with ages traditionally ascribed to some of the formations of northwestern Florida, the Yorktown and Waccamaw localities on the coastal plains of the eastern United States, the Moin Formation of Costa Rica, and the Encanto and Agueguexquite Formations of Mexico. Comparative ranges of these ubiquitous microfossils pose a Burdigalian age for the Chipola Formation, a late Langhian age for the Encanto and Yellow River Formations, a Tortonian to Messinian age for the Red Bay Formation, and an early to middle Pliocene age, at some localities, for the Jackson Bluff, Yorktown, and gueguexquite Formations. From several sites, material assigned to the Waccamaw Formation is correlated with the Moin Formation for which an early Pleistocene age is indicated. End_of_Article - Last_Page 1690------------