Late Quaternary Sequence Stratigraphy, South Florida Margin

ABSTRACT Late Quaternary sea-level change and the Florida Current nHave combined to produce a progradational shelf-slope Margin among the western portion of the south FloridaHat form facing the Straits of Florida. Analysis of highresoktion Seismic reflection profiles suggest at least eight 5th order late Quaternary sequences down onto the Portales Terrace at 250 m water depth. Alone most of the South F/ordeal margin, this Late Quaternary section is very Thin, and on/y where significant accumulations occur can The strafigraphic patterns produced by sea-level change be Clearly observed. Recognition of systems facts and their boundaries from High-resolution seismic data is important forpredicfion of Sedimentary fancies and stratigraphic development of Margins. Map south Florida seismic boundaries can be o the EXXON sequence strait ropy model, others Appear to reflect the added effect of buffo-current erosion Chaff complicates the signs/produced by sea-/eve/ change. Overall, fee sea-level signs appears to dominate the Strafigraphic record, especiallly from the 2-dimensions Perspective of dip-oriented seismic profiles. However, fee 3-dimensions geodesy of deposits are strongly Influenced by along open accumulation patterns controlledBy fee Florida Current. This study provides new in sight on fee importance of both Geosfrophic boundary currents and sea-level change in Controlling sfrafigraphic development of a carbonate platform Margin. Similar anomalously flick open deposits in Ancient sequences may indicate similar conform on accumulation and cooled end to predictions of related Pale-platform configurations. INTRODUCTION The South Florida Platform margin between Key West, Florida and the Dry Tortugas spans a transition from an Open non-rimmed margin to the west (Brooks and Holmes,1989) to a reef-rimmed margin along the Florida Keys (Eons and Perkins, 19n Shinn et al., 1989) (Fig 1). South Of the Marquesas Keys, this transition is marked by a Localized epicenter associated with broadening of a deep Outer shelf terrace. This local epicenter was constructed By a thick accumulation of protruding late QuaternaryDepositional sequences seaward of the inner shelf reef Margin. Two significant observations that have driven Research efforts to study the development of this Stratigraphic section are 1) a cyclic pattern of erosion and Procreation linked to sea-level fluctuations and 2) a high Sediment supply (off bank sediment transport, pelagic, and Reworked) derived from the adjacent reef margin. Both Have resulted in rapid procreation and preservation of Successive depositional environments (such as systemsTracts) characterized by distinctive acoustic fanciesPatterns bounded by erosion unconformities. The purpose of this paper is to illustrate the application of Sequence stratigraphic methods used to develop a stratigraphicFramework for this protruding section. Models to Characterize the stratigraphic development of carbonate Margins often emphasize tectonic setting, sea-level Change, and energy setting (windward vs. leeward) as key Factors controlling structural development and sedimentary Fancies architecture (Mullins and Neumann, 19793 Schaller and Ginsburg, 1981; Mullins and Cook, 1986). The Development and refinement of the EXXON sequence Stratigraphy concepts have come to play a major role in These models due to the potential for fancies prediction and Determining sea-level change (e.g. Posamentier and Vail, 1988; Locks and Sag, 1993).