NEW ESTIMATES FOR SALINITY CHANGES IN THE WESTERN PACIFIC WARM POOL DURING THE LAST GLACIAL MAXIMUM - OXYGEN-ISOTOPE EVIDENCE

Oxygen-isotope analyses of planktonic foraminifera from 57 western Pac ific deep-sea cores are compared for the Holocene and the Last Glacial Maximum (LGM). Carbonate dissolution, sedimentation rates/bioturbatio n, sample density, and vital effects are assessed before the sea-surfa ce salinity signal of these records is reconstructed. Average glacial- interglacial Delta delta(18)O values in the western Pacific are found to be close to those in the Atlantic Ocean (1.76 parts per thousand in the Pacific compared to 1.80 parts per thousand in the Atlantic), que stioning previous suggestions of a larger salinity difference between the Atlantic and the Pacific oceans during the LGM. During the LGM, se a-surface salinity was higher in the western Pacific than today (by > similar to 1 parts per thousand), implying that evaporation minus prec ipitation was higher all over the region. The minimum change in sea-su rface salinity occurred around the equator at the core of the Western Pacific Warm Pool. Holocene high-amplitude, high-frequency fluctuation s in planktonic delta(18)O records north and south of the present limi ts of the Western Pacific Warm Pool are indicative of sea-surface temp erature and/or sea-surface salinity variations related to its expansio n and contraction at the scale of thousands of years. Such high-amplit ude, high-frequency fluctuations at the edge of the WPWP are best docu mented in the delta(18)O signal of ODP Hole 828A offshore Vanuatu, so far the best high-resolution record for the western Pacific.