南海中部全新世以来海山深潜区有孔虫的地球化学记录及反映的气候变化  

Geochemical record of foraminifera and its reflection on climate change in the central South China Sea sinceHolocene

作　　者：杨俊[1,2] 赵彦彦 吴佳庆 魏浩天 龙海燕 李三忠[1,2,3] 毕乃双[2] YANG Jun;ZHAO Yanyan;WU Jiaqing;WEI Haotian;LONG Haiyan;LI Sanzhong;BI Naishuang(Key Laboratory of Submarine Geosciences and Prospecting Technique,Ministry of Education,Institute for Advanced Ocean Study,Ocean University of China,Qingdao 266100,China;College of Marine Geosciences,Ocean University of China,Qingdao 266100,China;Laboratory for Marine Geology,Qingdao National Laboratory for Marine Science and Technology,Qingdao 266061,China)

机构地区：[1]海底科学与探测技术教育部重点实验室和中国海洋大学海洋高等研究院,青岛266100 [2]中国海洋大学海洋地球科学学院,青岛266100 [3]青岛海洋科学与技术国家实验室海洋矿产资源评价与探测技术功能实验室,青岛266061

出　　处：《海洋地质与第四纪地质》2020年第2期100-110,共11页Marine Geology & Quaternary Geology

基　　金：国家自然科学基金“华南新元古代盖帽白云岩沉积微相的镁硅同位素研究”(41873006);青岛海洋科学与国家实验室鳌山科技创新计划“基于‘蛟龙号’深潜的南海若干关键地质与生物过程研究”(2016ASKJ05);试采海底孔隙压力监测与海洋物理环境研究项目(2018C-03-186);“海底透视”创新团队建设项目“南海全新世珊瑚礁高分辨率地球化学研究”(MGQNLM-TD201703)。

摘　　要：有孔虫在生长发育过程中能够捕获或黏附周围海水中的钙质或硅质形成自己的壳体,因此有孔虫的地球化学特征能够记录古气候、古海洋和古环境信息。以2017年蛟龙号第136潜次在南海珍贝海山底部约2500 m水深位置精准采集的柱状样品为研究对象,对其中的G.ruber以及G.sacculifer两类浮游有孔虫壳体的Mg/Ca以及碳氧同位素组成进行了分析测试。结果表明自12.6 ka以来该海域表层海水温度(SST)的变化范围为24.4~29.3℃,平均温度为26.2℃,并能够识别出明显的气候突变事件,在时间范围上与新仙女木事件和全新世东亚夏季风突变事件大致吻合。这些突变事件可能受控于ENSO活动和热带辐合带(ITCZ)平均位置的纬向移动,并与北大西洋冰筏事件具有遥相关。此外,发现全新世期间浮游有孔虫G.sacculifer和G.ruber的碳同位素分馏值Δ^13CG.sacculifer-G.ruber与SST变化有关,SST降低时,Δ^13CG.sacculifer-G.ruber呈负偏;而在SST升高时,Δ^13CG.sacculifer-G.ruber呈正偏。Foraminifera form their crust by absorption or capture of calcium or silica from the seawater they live in.As the results,the geochemical features of the crust are the efficient indicators of palaeoclimate,palaeooceanography and palaeoenvironments during their life.In the year of 2017,columnar samples of a pushcore were collected by the“Jiaolong”submersible precisely at the foot of the Zhenbei seamount near the Huangyan Island in the Middle of South China Sea.The Mg/Ca ratios and the carbon and oxygen isotope compositions of the planktonic foraminifera Globigerinoides ruber and Globeriginoides sacculifer shells were measured to trace the history of sea surface temperatures(SST)and influence parameters.The results show that the SST in the sea area varied from 24.4 to 29.3℃since 12.6 ka with an average of 26.2℃.Some cold events can be the obviously identified,which could be correlated with the events of Younger Dryas and Holocene East Asian summer monsoon.These events may be controlled by the ENSO activities and the shift of the mean location of ITCZ,and even influenced by the North Atlantic ice rafting events.In addition,we found that during the period of Holocene the fractionation ofΔ^13CG.sacculifer-G.ruber between the carbon isotope compositions of G.sacculifer and G.ruber may also be constrained by SST since theΔ^13CG.sacculifer-G.ruber values was negatively biased when SST decreased and vice versa.

关 键 词：浮游有孔虫 MG/CA 氧同位素 碳同位素分馏 黄岩岛 

分 类 号：P736.4[天文地球—海洋地质]