COVINGTON, MITCHENER, Florida Geological Survey, BugWare Inc., Tallahassee, FL

ABSTRACT: Neogene Nannofossils of Florida

Cores from various geographic provinces in Florida have been examined for nannofossils. While biostratigraphic control in some cores is inhibited by poor preservation and/or paleoenvironmental constraints, other cores contain a sufficient amount of adequately preserved nannofossils to provide good biostratigraphic resolution. As may be expected, wells from coastal areas yielded significantly more abundant and diverse assemblages than those further inland. Wells from the eastern coastal areas adjacent to the Atlantic Ocean generally yielded better assemblages than those adjacent to the Gulf of Mexico. It is unclear at this time how nannofossil preservation has been affected by ground-water circulation, but obliteration of nannofossils from dissolution and recrystallization may have bee significant.

Nine southwestern Florida wells were studied from Charlotte and Lee Counties, including Charlotte Harbor. In general, the cores may be characterized as containing nannofossils of Early to Late Pliocene age at or near the surface, to late Early Niocene (CN2-3) in the deepest sample from 504'.

Three wells from the coastal area of Walton County in the panhandle of Florida all yielded cores containing nannofossils which indicate ages of Early to Late Pliocene (Zones CN11/12) near the surface. A hiatus is evident in these wells at roughly 200', with sediments assigned to Zone CN11 directly overlying sediments assigned to Zone CN4-6 (Middle Miocene).

One well from the eastern coastal Indian River County yielded abundant and diverse nannofossils with age determinations including Early Pliocene (CN9) at 120', early Late Miocene (CN8) at 221', and earliest Miocene to latest Oligocene at 332'.

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana, April 25-28, 1993.