Pore Fluid Constraints on Deep Ocean Temperature and Salinity during the Last Glacial Maximum

Abstract. Pore water records of 18O and [Cl] from ODP Site 1063A on the Bermuda Rise constrain the change in seawater 18O and salinity from the Last Glacial Maximum (LGM) to the Holocene to be 0.75±0.05 ‰ and 2.5±0.1 % respectively. Coupled with a measured benthic foraminiferal 18O change, this result means that bottom waters were 4.6±0.8°C cooler than the Holocene at the LGM and therefore at or near the seawater freezing point. Coupled 18O and chlorinity results give an extrapolated mean ocean LGM to Holocene change in 18O of 0.95±0.09‰. These data also constrain the past southern source deep-water salinity to be 35.76±0.04 psu, which is within error of the mean deep ocean value for this time. 1