CORAL FAUNAL PARTITIONING AND REEF DEVELOPMENT WITHIN A MIXED CARBONATE-SILICICLASTIC SEQUENCE STRATIGRAPHIC CONTEXT

We report on an extensive collection of Miocene and Pliocene corals from the mixed carbonate-siliciclastic deposits of the Cibao Basin, northern Dominican Republic. Over 8,000 corals specimens have been collected and identified to the species level. A total of 114 species belonging to 38 genera have been identified from the Cercado, Gurabo, and Mao Formations. Of the 114 species identified, 52 have global first occurrences within the study area, 30 have global last occurrences, and 27 (24%) are living taxa in the Caribbean today.

To evaluate the large-scale patterns of faunal partitioning and reef development within a sequence stratigraphic context, sample collections were subdivided into 20 well-dated lithostratigraphic units based on the major sequence stratigraphic and lithologic boundaries. In general, coral assemblages of the three formations can be subdivided into two distinct community types: (1) Free-living coral assemblages composed primarily of members of the genera Antillia, Antillophyllia, Manicina, Meandrina, Placocyathus, Thysanus and Trachyphyllia, and (2) mixed-shape assemblages of species from the genera Porites, Stylophora, Montastraea, Stephanocoenia, Goniopora and Undaria. The free-living coral assemblages appear to occur during low-stand and transgressive systems tracts. The lithostratigraphic units dominated by free-living coral species separate three intervals of more significant reef development. These reef building periods form during the highstand and falling stage systems tracts, coincident with rapid progradation within the basin. Each of these reefs provides a unique example of coral reef growth in a mixed carbonate-siliciclastic system.