Late Eocene Echinoid Biofacies of Florida

Abstract

Combining the substrate preferences of Jacksonian (late Eocene) echinoid species of Florida (Carter et al., 1989) with their geographic distributions (Carter, 1987a) allows construction of biofacies maps reflecting the spatial distribution of carbonate mud-rich and carbonate sand-rich sediments in the Ocala Group of Florida. Both cluster analysis and interpretation of individual localities suggest a consistently sandy bottom over most of the shelf in the early Jacksonian, with a north-south gradient developing during the middle and late Jacksonian. In the middle Ocala, some mud-tolerant species are present in the northern part of the Florida peninsula, toward the Suwannee Strait, and the middle Ocala of the western panhandle is dominated by mud-tolerant species. In the upper Ocala, most localities contain a significant proportion of mud-dwelling species, and the northward prevalence of mud-tolerant assemblages is even more pronounced, with those assemblages closer to the Suwannee Strait entirely dominated by mud-dwellers. These data suggest that the Ocala Bank of Cheetham (1963) was more of a northward sloping carbonate ramp than a carbonate shelf.