The sedimentary succession of piston core RC26-16, dated by 14C accelerator
mass spectrometry, provides a nearly continuous palaeoceanographic record of the northeastern
South China Sea for the last 15 000 yr. Planktic foraminiferal assemblages indicate that winter
sea-surface temperatures (SSTs) rose from 18°C to about 24°C from the last glacial to the
Holocene. A short-lived cooling of 1°C in winter temperature centred at about 11 000 14C yr
ago may reflect the Younger Dryas cooling event in this area. Summer SSTs have remained
between 27°C and 29°C throughout the record. The temperature difference between summer
and winter was about ca. 9°C during the last glacial, much higher than the Holocene value of
ca. 5°C. During the late Holocene a short-lived cooling event occurred at about 4000 14C yr
ago. Oxygen and carbon isotopic gradients between surface (0–50 m) and subsurface (50–100
m) waters were smaller during the last glacial than those in the Holocene. The fluctuation in
the isotopic gradients are caused most likely by changes in upwelling intensity. Smaller gradients
indicate stronger upwelling during the glacial winter monsoon. The fauna-derived estimates of
nutrient content of the surface waters indicate that the upwelling induced higher fertility and
biological productivity during the glacial. The winter monsoon became weaker during the
Holocene. The carbonate compensation depth and foraminiferal lysocline were shallower during
the Holocene, except for a short-lived deepening at about 5000 14C yr ago. A preservation
peak of planktic foraminifera and calcium carbonate occurred between 13400 and 12 000 14C
yr ago, synchronous to the global preservation event of Termination I.
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