Paleotempestite Distribution across an Isolated Carbonate Platform, San Salvador Island, Bahamas

Sediment cores were collected from coastal ponds across San Salvador Island, an isolated Bahamian carbonate platform, and integrated with aerial photographs and field-survey data to provide insight into how spatially variable storm records are at the island scale and what drives this-variance. A better understanding of local tempestite generation and preservation potential is crucial for correlating events across more regional scales. Sandy storm layers, products of beach overwash and/or high-energy aeolian transport from the shore into coastal ponds, are easily distinguished from flocculated carbonate muds, microbial mats, and other organics that ordinarily sequester in the stagnant, low-energy coastal water bodies. Interpreted paleotempestites do not correlate well between studied ponds using a strictly stratigraphic approach, although all sites investigated are situated within 150 m of a sandy beach, are similar in size and morphology, and coastal terrains across the small island are comparable. While wrack lines show that individual storms produce surges that vary in height along the island's 60 km-long coastline, differences in the spatial distribution of storm deposits cannot be explained solely as a function of variable surge heights, storm trajectories, and shore aspect; they also reflect intrinsic, biogeomorphic variables such as pond-fringing vegetation characteristics and coastal geomorphic configuration. A complete storm chronology for the island is not generated in any single pond location, and diagenetic processes compound this variance, producing a high degree of spatial heterogeneity of storm records. Nonetheless, the Caribbean-wide Hurricane Hyperactivity Period is distinguished in core from the modern period of relative inactivity by an up-core transition from sandy, stratified pond deposits containing storm layers to heavily bioturbated sediments indicative of low-E deposition. This facies transition, recognized across the island, provides a regional correlation tool for evaluating the distribution of paleotempestites within context of major climate regimes.