The Misery Point cliff, Mayaguana Island, SE Bahamas: a unique record of sea-level highstands since the Early Pleistocene

摘要

We describe in detail a unique succession of Lower Pleistocene shallow-water carbonates exposed at the Misery Point sea cliff along the northern shoreline of Mayaguana Island (SE Bahamas). This km-scale outcrop comprises a record of seven past sea-level highstands that occurred between ca. 1.3 Ma and 125 ka ago, and reached relative elevations from 3 to possibly 14 m above modern sea level. Considering the tectonic stability of the Mayaguana platform in the Quaternary, the amplitudes of the recorded events could be fairly close to the corresponding glacio-eustatic changes, and thus provide calibration points for sea-level proxies derived from the deep-sea oxygen-isotope records and ice-sheet models. Moreover, our study traces the evolution of the Mayaguana bank over the past 1.3 million years, provides some insight on the birth of possibly the first island of the Bahamas archipelago, and emphasizes that the shift from bioclastic to oolitic-peloidal carbonates (i.e. the transition from the pre-Lucayan to the Lucayan limestones) occurred much later on this platform than on the northern Bahamian banks, which raises questions about the origin of this transition.