南海东北部末次冰期—全新世古海洋学  

LATE GLACIATION HOLOCENE PALEO OCEANOGRAPHY OF THE NORTHEASTERN SOUTH CHINA SEA:CORE RC26 16

作　　者：魏国彦[1,2,3] 李孟扬 段威武[1,2,3] 陈超云 汪中和[1,2,3] 

机构地区：[1]台湾大学地质系 [2]国土资源部广州海洋地质调查局 [3]台湾科学院地球科学研究所

出　　处：《海洋地质与第四纪地质》1999年第3期19-28,共10页Marine Geology & Quaternary Geology

摘　　要：据加速器质谱仪１４Ｃ测年，ＲＣ２６－１６孔提供了南海北部近１５２００ａ来古海洋学的连续沉积记录。其古海洋学发展过程可分为３期，（１）最后冰期（１５．２～１３．３ｋａ）；（２）冰消期（１３．３～９．０ｋａ）；（３）间冰期（９．０ｋａ～现代）。末次冰期至全新世时，冬季海水表层温度由１８℃上升至２４℃，夏季则保持在２７～２９℃之间。在１１ｋａ时，冬季水温曾短暂的一度变凉（约３℃），此可能代表区内新仙女木事件。末次冰期时，夏季与冬季温度差约为９℃，它的变化幅度较全新世的５℃要大。末次冰期时，表层水（０～５０ｍ）与次表层水（５０～１００ｍ）间碳、氧同位素递减梯度较全新世的为小。１５～１３ｋａ时大洋表层动物衍生营养含量相对较高，推测这与较强的冬季风导致较强的上升流，而造成高养分和高生物生产率有关，全新世时冬季风变弱。全新世碳酸盐补偿深度和有孔虫溶跃层较浅，５．３ｋａ时有短暂的变深，浮游有孔虫保存高峰和碳酸钙高峰值发生在１４～１２ｋａ间，相当于全球性的ＴｅｒｍｉｎａｔｉｏｎⅠ事件。A piston core,RC26 16,dated by 14 C accelerator mass spectrometry,provides a nearly continuous paleo oceanographic record of the northeastern South China Sea for the last 15 200 years.The paleo oceanographic development can be subdivided into three stages:(1)last glacial stage from 15 2 to 13 3 ka,(2) deglacial stage from 13 3 to 9 ka,and (3) interglacial stage from 9ka to the present. Winter sea surface temperatures rose from 18° C to about 24° C from the last glacial stage to the Holocene.A short lived cooling of 3° C in winter temperature,centered at about 11ka,may reflect the Younger Dryas cooling event in this area.Summer sea surface temperatures have remained between 27° C and 29° C throughout the record.During the last glacial stage,temperature difference between summer and winter was about 9° C,much higher than the Holocene value of about 5° C. Oxygen and carbon isotopic gradients between surface(0～50 m)and subsurface(50～100 m)waters during the last glacial stage were smaller than those in the Holocene.Fauna derived estimates of nutrient contents of the surface ocean were relatively high during 15～13 ka.We suggested that the relatively strong glacial winter monsoon may have caused stronger upwelling and,hence,induced higher fertility and biological productivity.The winter monsoon became weaker during the Holocene. Carbonate compensation depth and foraminiferal lysocline were shallower during the Holocene except for an short lived deepening at about 5 3 ka.A preservation peak of planktonic foraminifera and calcium carbonate occurred between 14 and 12 ka,synchronous with the global preservation event of Termination Ⅰ.

关 键 词：古海洋学 晚第四纪 南海北部 末次冰期 全新世 

分 类 号：P736.22[天文地球—海洋地质]