A replicated record of multi-centennial climate variability in the northern Gulf of Mexico spanning the last 4.4 kyrs from paired δ18O and Mg/Ca in G. ruber

Sea-surface temperatures (SST) in the Gulf of Mexico (GOM) are an important influence on the moisture budget of the Western Hemisphere and play a key role in tropical to extra-tropical heat transport in the region. Changes in the hydroclimate of the GOM region also influence sea-surface salinity (SSS). Marine sediment records from the Pigmy Basin suggest significant SST variability in the northern GOM over the last two millennia. Some, but not all of this SST variability is also observed in paleoclimate records from the Caribbean-GOM region. To assess the spatial coherency of a regional SST signal, we present marine sediment records from another GOM basin, Garrison Basin (26°43'N, 93°55'W), which is located ~250 km west of Pigmy Basin. We generated time series of paired Mg/Ca (SST proxy) and δ18O (SST and SSS proxy) variations in planktic foraminifer Globigerinoides ruber (white variety) from three multi-cores collected in 2010. A radiocarbon-based chronology indicates that these cores span the last 4400 calendar yrs BP. Initial stable isotopic results reveal excellent replication between the multi-cores and indicate coherent, multi-centennial variability in foraminiferal δ18O. Preliminary Mg/Ca-SST results from one of the cores compare well with published results from the Pigmy Basin. Our replicated results in tandem with a Mg/Ca-δ18O calibration study from a sediment trap located ~350 km east of the Garrison Basin lend confidence that downcore geochemical variations in this region are a robust record of paleoclimate variability.