A Geomorphological Approach to Carbonate Sand Searches

Geophysical data obtained during an offshore geotechnical sand-search defined the surficial extent and sub-bottom configuration of geomorphological features such as reef tracts, infills of carbonate sediments within back reef troughs, and karstified rock outcrops along the upper shoreface. Coastal process zones (CPZ) were derived from interpretation of spatial distribution patterns of morphostructural units. Recognition of discrete morphostructures and CPZs additionally provided a basis for conceptualizing a new model for exploration of offshore sand deposits that are suitable for beach renourishment. Morphostructural mapping showed that the present carbonate setting can be explained in terms of representative CPZs. The relationships between form and function, including paleoforms and processes as relics in the present environment, distinguish sediment distribution patterns and CPZs that typify this carbonate arena. Uniformly graded clastic sediments are deposited in inter-reefal flats that act as a depocenters for accumulating calcareous sands. The intersection of para- and diabathic process zones at reef gaps produces mixed sand bodies that are also useful for beach replenishment. Study of morphostructural units and coastal process zones, provides a useful exploration paradigm for seabed sand sources within the dimensional framework of the southeast Florida Sand Search Model.