Abstract:
Multifold and singlefold seismic data, industry wells, and DSDP/ODP sites are used to study the mid-Cretaceous-Cenozoic history of the southern Straits of Florida. Since the late Albian(?), the southern Straits of Florida has evolved from a shallow-water platform to a deep water trough. Persistent Florida Current flow has existed since the early Paleocene and has produced a complex history of deposition and erosion. Initiation of Florida Current flow and evolution of the Straits of Florida is related to the Late Cretaceous-middle Eocene collision between the North America plate and the Cuban island arc. During the Early Cretaceous, a shallow-water carbonate platform-complex extended from the West Florida Shelf across what is now the Straits of Florida and northern Cuba to the Bahamas. Drowning and breakup of this broad platform began during the late Albian(?) to middle Cenomanian. During this drowning event, shallow-water buildups continued to develop at the Lower Cretaceous platform margin, around Cay Sal Bank, and along the southern margin of the South Florida basin. The Mid-Cretaceous Sequence Boundary (MCSB), a regional seismic horizon, is recognized in the southern Straits of Florida and marks the demise of shallow-water carbonate production at the Lower Cretaceous platform margin. During the Late Cretaceous to early Paleocene, a deep-water seaway, a proto-Straits of Florida, separated carbonate banks at Cay Sal and along the South Florida basin. As the Cuban island arc converged on the North American plate during the Late Cretaceous-middle Eocene, the southern Straits of Florida were downbuckling to the south in response to loading. Most of the deformation occurred along an east-west flexure. Regional dip towards the Cuban fold-and-thrust belt indicates that the southern Straits can be considered an extension of the north Cuban foreland previously identified in the southeastern Gulf of Mexico. Seismic facies indicate that bottom-currents were active along the northern limb of this foreland basin during the early Paleocene to middle Eocene, producing a variety of bedforms and erosion surfaces. These current-deposits are interpreted to be reworked, distal equivalents of flysch, olistostromes, and debris flows shed from the island arc complex. After Cuba was welded to the North American plate during the late Eocene, there was a major change in depositional regimes from current-produced deposition to drape deposition in the southern Straits. A major late-middle Eocene seismic unconformity separates current-deposited sediments from predominantly pelagic and hemipelagic sediments interbedded with distal turbidites. Since the Late Eocene, the axis of Florida Current flow appears to have been concentrated above the east-west trending flexure. During the middle Miocene, shallow-water carbonate sediments were deposited along the Miami and Pourtales terraces. Since the middle Miocene, sediment drifts have continued to be deposited basinward of the Miami and Pourtales terraces.