Ichnofacies, Ichnocoenoses, and Ichnofabrics of Quaternary Shallow-Marine to Dunal Tropical Carbonates: A Model and Implications

A model of five ichnocoenoses within the Skolithos and Psilonichnus ichnofacies characterizes the modern, Holocene, and Pleistocene coastal-carbonate depositional environments and limestones of the Bahamas, as well as the Miami Limestone of south Florida. The subtidal to intertidal ichnocoenoses of the Skolithos ichnofacies are dominated by trace-making activities and trace fossils of callianassid shrimp, which can create distinctive and maximum ichnofabrics. Fossil Upogebia vasquezi burrows found in intertidal calcarenites and burrows of the trace fossil Psilonichnus upsilon, most common in beach backshore beds, have excellent potential as stratigraphic markers and can be used as indicators of past sea-level positions. The dunal ichnocoenosis exhibits a high ichnodiversity owing to the presence of arthropod-generated trace fossils and rhizomorphs, resulting from the activities of plants; trace fossils created by insects can be large and complex and can impart distinctive ichnofabrics to eolianites. Ichnologic studies of modern tropical carbonate environments and their rock-record equivalents have great potential for future development, and information from carbonates should be fully integrated with that of siliciclastics, with carbonates not viewed as a separate ichnologic subdiscipline.