Unraveling the Spatial Variability of Fossil Coral Reef Morphology on Aruba and the Implications for Paleo Sea Level Estimates

The morphology of a coral reef terrace (CRT) is a key parameter in the interpretation and quantification of past sea-level changes, but it is directly influenced by local morphodynamic and hydrodynamic conditions. Spatial differences in terrace morphology may therefore result in over- or underestimation of paleorelative sea levels and their associated uncertainties. To investigate this, we integrate high-precision field surveys from the island of Aruba (Leeward Antilles, Caribbean Sea) with a stratigraphic forward model (DionisosFlow®) to quantify the intra-island variability of the Quaternary coral reef sequence. We establish that a possible slight North-South tectonic tilt of the island may drive differences in the elevation of CRTs and the number of emerged fossil coral reefs imprinted on the coastal landscape. However, terrace geometry is primarily defined by the basement slope and wave exposure. All together, our results show that even small-scale environmental and hydrodynamic variability can introduce meter-scale errors in sea-level reconstructions derived from CRTs.