Abstract >Introduction Background Methods Seismic Sequences Discussion Conclusions & Acknowledgments References Tables PDF Version

The integration of marine seismic-reflection profiles and well data has been used successfully in the offshore marine environments of southern peninsular Florida to develop convincing stratigraphic models of the complex Neogene alternations of carbonate and siliciclastic sediments and rocks (Missimer and Gardner 1976; Warzeski et al. 1996; Missimer 1999). These data show the invasion of Late Miocene to Pliocene siliciclastics onto Middle Miocene to early Late Miocene carbonates at the southeastern part of the Florida Platform (Guertin et al. 2000; Cunningham et al. 2001a) and a return to carbonate deposition during the Quaternary (Enos and Perkins 1977). This study focuses on the southwestern part of the Florida peninsula (Fig. 1), an area of special interest, because it is located along a narrow north-to-south route defined by the coarsest fraction of these invasive quartz sands (Warzeski et al. 1996; Cunningham et al. 1998). This pathway was interpreted by Warzeski et al. (1996) as the palimpsest record of strong paleocurrents associated with a southward-moving shoreline and channeled deposition, or a giant prograding spit along the western side of southern peninsular Florida. These currents presumably acted to transport a huge amount of siliciclastics over the carbonate Florida Platform towards its southeastern edge during the Late Miocene and Pliocene.

In this paper we present: (1) new core and high-resolution seismic-reflection data from southwestern Florida (Fig. 1) that are interpreted to show southward transport of the siliciclastics principally via a deltaic depositional system; (2) introduce a seismic-sequence stratigraphy, nannofossil biostratigraphy, and strontium-isotope chemostratigraphy that constrain the age of this deltaic system, as well as underlying and overlying sequences; and (3) speculate on mechanisms that influenced the demise of carbonate deposition on the southeastern Florida Platform during the Miocene and Pliocene, the replacement of carbonate growth by Late Miocene to Pliocene siliciclastic deposition, and the recovery of carbonate deposition in the Quaternary. Studies of the role of siliciclastics on the initiation and expansion of carbonate platforms have been conducted on a number of different shelves and slopes (Choi and Ginsburg 1982; Choi and Holmes 1982; Davies et al. 1989; Meyer 1989; Sonnenfeld and Cross 1993; Southgate et al. 1993; Warzeski et al. 1996; Ferro et al. 1999). Our new data provide an opportunity to explore the effect siliciclastics have on rejuvenation of carbonate production on a carbonate platform.