Caribbean reefs changed profoundly in taxonomic composition, diversity, and dominance structure during late Pliocene and Pleistocene climatic change. These changes coincide with protracted climatic deterioration and cooling between 2.0 to 0.8 Ma, and the onset of high amplitude sea-level fluctuations ~400 ka. The Dominican Republic Drilling Project (DRDP) was initiated to determine how climate change and global high-amplitude sea level changes influenced depositional patterns in Pliocene to Recent reef systems of the Caribbean. A transect of 7 core borings (~700 m total depth) were collected along the southern coast of the DR, constrained in age by U/Th and U/Pb geochronometry, radiogenic Sr isotopes, and several diagnostic calcareous nannofossil biomarkers. In the two seaward cores, 7 sequences were recovered associated with sea level fluctuations (Marine Isotope Stage 5e at ∼128 ka to MIS 17 at ∼700 ka). A U-Pb age of 0.646±0.013 Ma (2σ) for the shallow reef deposits at -110 m record deposition during sea level lowstand MIS 16. The highstand flooding at MIS 11 marks a sedimentological transition. Reef development in the shallow shelf resulted in more carbonate production, steeper slopes and significant carbonate shedding into the forereef. The sequences of MIS 11 to MIS 5 show an overall shallowing-upward trend, where transgressive cycles are less evident as the margin prograded seaward. Coral records from these cores indicate that most extinction had occurred prior to ~1 Ma (MIS 31). Following this extinction, fringing reef margins of the Caribbean display a characteristic zonation in which Acropora palmata dominates shallow high-energy reef crests and Acropora cervicornis calmer fore-reef slopes and backreef lagoons. The dominance of acroporids across this zonation has been attributed to growth rates 5-100 times faster than other corals.
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