The west Florida continental shelf consists of a thin veneer of carbonate and siliciclastic sediments overlying an irregular limestone surface. As part of a five-year study funded by the USGS, over 200 vibracores and 500 bottom samples were collected within 30 km of shore in an attempt to ascertain the recent depositional history of the inner west-central Florida shelf, and how it relates to the development of the barrier island coastal system. Nine lithofacies have been identified representing pre-Holocene, transgressive back barrier/estuarine, and highstand open-marine environments. Facies associations indicate three distinct successions. In the seaward-most portion of the study area modern marine (high-stand) deposits consisting primarily of carbonate-rich sands, directly overlie pre-Holocene deposits. In the southern-most portion of the study area south of Tampa Bay, modern marine (high-stand) sediments, in this case consisting primarily of black sands, also immediately overlie pre-Holocene deposits. North of Tampa Bay and near to shore, modern marine sediments consisting primarily of quartz sands, overlie back barrier/estuarine deposits, which overlie the pre-Holocene deposits. In this last case, modern marine deposits are often separated from back barrier/estuarine deposits by a ravinement surface. The distribution of facies associations suggests that the inner shelf developed as a sediment starved platform and is interpreted to be controlled by the rate of sea-level rise, antecedent topography, and sediment source/supply rate. It also implies that barrier island development occurred late during the Holocene transgression, and was more prominent in the northern part of the study area.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas