A Quest for Correlation: Finding Support for a Layer-Cake Model in the Florida Panhandle

For the application of the principles of Neo-Ulrichian layer-cake stratigraphy to a coastal setting, necessitats the tracing of the lateral extent of lithologic beds over a broad area. In this study of nine counties in the FL Panhandle, well cores tied to available exposed sections, were used to form the stratigraphic framework from which several lithologic patterns, disconformities and individual beds could be correlated. Specifically, two glauconite-rich clay beds bounded by carbonates which may represent highstand deposits and illustrate the influence of large-scale eustatic processes. There was also an abrupt shift from carbonate to siliciclastic sedimentation that was traceable across the study area. The finding of these units supports the concepts of a layer-cake stratigraphic model and can be confirmed using in depth comparisons of mineral compositions, fossil assemblages and cyclic packages. These data were acquired through visual analysis of cores stored at the Florida Geologic Survey core facility in Tallahassee. They were also compared against and used in conjunction with descriptions from the SOFIA database to interpret their depositional environments and recognize possible unconformities (‘frosting layers') through the application of Walther's law which states that depositional environments coexisting laterally must occur in superposition unless an unconformity is present. Qualitative observations also helped to constrain the lateral change and variation of these environments represented within the cake layers and to map them across the study area. This allowed for the creation of a model that could be checked against eustatic changes to further constrain the timing of each bed. Confirmation that the beds are traceable throughout the study area, would allow a layer-cake model to be applied and used to group isochronous facies into larger units encompassing the range of variation in depositional environments that can occur within a dynamic passive-margin, coastal environment.