QUATERNARY GEOLOGY OF THE SOUTH AND WEST FLORIDA SHELVES—BEGINNING OF A SYNTHESIS

Since 1956 when the oft-cited Gould and Stewart paper (SEPM Special Publication #3) appeared describing the distribution of surficial sediments on the west Florida shelf (WFS), there have been numerous site-specific studies examining relatively small “postage stamp” sized targets of interest (e.g., Pulley Ridge, Florida Middle Ground, Dry Tortugas). The combined south and west Florida shelves extend over an area larger than the emerged State of Florida. This fact makes any regional synthesis based on a single field study impossible given the cost and logistical problems posed by marine research. However, widely dispersed, collective efforts by many over the past 50 years provide a minimal data base to begin to develop a broader understanding of what geologic features exist, when they formed, what processes have converged to create them, and how they can be placed into a sequence stratigraphy/systems tract context based on Milankovitch-scale sea-level forcing.

First order trends such as siliciclastics dominating the northern portions of the WFS transitioning southward into a pure carbonate end member have long been known. Additionally, the ramp-style transitioning southward to a rimmed margin morphology, thin sedimentary cover, seemingly featureless topography and wide exposures of Cenozoic limestone have been well-used descriptors. But, the detection and recognition of many new geological features such as drowned shorelines and eolian dunes, deep reefs (living and dead), outlier reefs, scarps, shelf valleys, linear sand shoals, relict deltas, etc. now allow us to develop a rationale synthesis of when and where these and other features were formed during a sea-level cycle.

We recognize three basic types of sequences: (1) siliciclastic; (2) mixed siliciclastic/carbonate, and (3) carbonate. Although generic models of these three sequences have long been established, we present one of each using the unique geologic characteristics of the south and west Florida shelf. But, there still remain great voids in our knowledge and understanding about Quaternary stratigraphy and the surficial distribution of geologic products and the processes that shaped them in this area.