Palaeoceanographic change in the northeastern South China Sea during the last 15000 years

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Title:	Palaeoceanographic change in the northeastern South China Sea during the last 15000 years
Authors:	KUO-YEN WEI MENG-YANG LEE WEIWU DUAN CHAOYUN CHEN CHUNG-HO WANG 李孟陽汪中和
Contributors:	臺北市立教育大學自然科學系
Keywords:	palaeoceanography South China Sea deglaciation Holocene
Date:	1998
Issue Date:	2009-07-31 11:27:45 (UTC+8)
Abstract:	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.
Relation:	JOURNAL OF QUATERNARY SCIENCE , v13 (1), p.55–64
Appears in Collections:	[Department of Applied Physics and Chemistry] Periodical Articles

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