TECTONICS AND STRATIGRAPHY OF THE JURASSIC-CRETACEOUS CUBA-BAHAMAS SEDIMENTARY PROVINCE: A RECORD OF RIFTING, RESTRICTED EVAPORITE TO MARINE BASIN, CARBONATE PLATFORMS AND TECTONIC INVERSION

The Jurassic-Cretaceous stratigraphy of the northern margin of Cuba and the southern Bahamas records late-stage breakup of Pangea during the early Jurassic opening of the North Atlantic and later inversion during collision of the Caribbean tectonic plate. Rifting along the US Atlantic East Coast extended through the Bahamas, Cuba and into the Takatu rift of Guyana and Brazil prior to separation of North and South America. Rifting occurred in the Santaren and Old Bahamas Channels in the southern Bahamas and northern Cuba, where onshore Cuba are reported Middle Jurassic continental strata. With the opening of the Gulf of Mexico (GoM) during the Oxfordian, Cuba formed the southern extension of a carbonate mega-bank platform system.

The Santaren Basin is a deep basin, likely >60,000 ft, made up of high-reflectivity horizons of ‘basinal’ Jurassic carbonate- evaporite marine strata, which in core are base-level deepening cycles sitting seaward of the reef margin. Reefs rimmed the basin and in places set-up on rift-shoulder fault blocks. Platform top and interior strata consist of base-level cycles of oolitic sands, restricted marine mud-supported sediments and subaqueous evaporites.

The reef-rimmed platform is best defined along the eastern margin of the Santaren Basin and along the Great Bahama Bank as a southward-facing margin fronting the evaporite-marine basin. A north-facing carbonate platform developed onshore Cuba and extended northward along the western margin of the basin onto Cay Sal Bank. The north-facing Cuban platform crops out in onshore Cuba. These opposing platform margins (Cuba and southern Bahamas) faced each other and were only separated by a restricted evaporitic-marine basin filled with alternating anhydrite, salt and carbonate strata.

The reef-rimming margins continued into the Late Cretaceous when eustatic sea-level rise resulted in margins drowning or migrating’ landward’ (backstepping). Late Cretaceous platforms aggraded and over-steepened. Along the southern Cuban platform, the platforms remained drowned prior to plate collision and overthrusting. Seismically defined scalloped margins indicated collapse and mass-wasting near the terminus of the Late Cretaceous and plate boundary collision (Late Paleocene).