DETERMINATION OF DELTA-O-18 OF SEAWATER IN THE DEEP OCEAN DURING THE LAST GLACIAL MAXIMUM

We present a method for determining the deltaO-18 of seawater in the deep ocean during the last glacial maximum from the measured deltaO-18 values of deep sea pore fluids. Using data from Deep Sea Drilling Project (DSDP) site 576 in the Western Pacific, this method yields a glacial to interglacial change in deltaO-18(sw) of 1.0+/-0.25 parts per thousand. This value for DELTAdeltaO-18(sw) is the first direct measurement of deep ocean deltaO-18 for the last glacial maximum and avoids the problems of spatial and temporal variability of the deltaO-18 of surface water implicit in previous determinations. More precise, higher-resolution pore fluid measurements are required to improve this determination.