HOW FAR INTO THE CARIBBEAN DOES FOREBULGE INDUCED SUBSIDENCE EXTEND? A NEW SEA LEVEL CHRONOLOGY FROM THE TECTONICALLY STABLE CENTRAL COAST OF COLOMBIA

Several recent reviews of paleo-sea-level data from the circum-Caribbean region have shown that the Holocene sea level history of the southern Caribbean is poorly constrained. Relative sea-level (RSL) data from this large area is mostly found in unpublished studies and it often contains large age and altitude errors. The lack of good quality data has limited the sea level modelling community to run simulations with coarse latitudinal resolution, as such, the spatial extent of forebulge subsidence and emergence of mid-Holocene high-stand on the southern Caribbean region is not well documented. To increase the spatial coverage and add to the understanding of regional variability of RSL change across the Caribbean, a new sea-level chronology is presented for the tectonically stable central Caribbean coast of Colombia. Common along this coast are coastal lagoons containing thick sequences of organic deposits with the potential to capture a substantial portion of the Holocene transgression. The new record captures >6 meters of RSL rise and indicates gradual rise from -7.7 m at 7300 years BP to -1.6 m at 4300 years BP. A possible deceleration in the rate RSL rise is suggested at 6000 years BP, but there is no evidence of a mid-Holocene high-stand. These findings validate those from two recent studies that employed statistical and geophysical models and fail to produce higher than present sea level in the mid Holocene. The RSL signal on the continental margin of northern South America, >3000 km from the southern margin of the Laurentide Ice Sheet, is dominated by forebulge subsidence.