南海北部31 ka以来GDGTs组成及其对古温度和季风变化的响应  

Composition of glycerol dibiphytanyl glycerol tetraethers(GDGTs)and its responses to paleotemperature and monsoon changes since 31ka in northern South China Sea

作　　者：刘磊 管红香[1] 冯俊熙[3] 许兰芳 茅晟懿[1] 刘丽华[1] LIU Lei;GUAN Hongxiang;FENG Junxi;XU Lanfang;MAO Shengyi;LIU Lihua(Key Lab of Renewable Energy and Gas Hydrate,Guangzhou Institute of Energy Conversion,Chinese Academy of Sciences,Guangzhou 510640,China;University of Chinese Academy of Sciences,Beijing 100049,China;Guangzhou Marine Geological Surveys,Guangzhou 510760,China)

机构地区：[1]中国科学院广州能源研究所,中国科学院天然气水合物研究重点实验室,广州510640 [2]中国科学院大学,北京100049 [3]中国地质调查局广州海洋地质调查局,广州510760

出　　处：《海洋地质与第四纪地质》2020年第3期144-159,共16页Marine Geology & Quaternary Geology

基　　金：国家自然科学基金项目“南海北部陆坡不同矿物组分冷泉碳酸盐岩”(91958105);青岛海洋科学与技术国家实验室开放基金“冷泉区双壳和管状蠕虫环境中自生碳酸盐岩的有机地球化学对比研究”(QNLM2016ORP0210);广州市科技计划项目“南海北部神狐钻探区自生黄铁矿形成机制及其指示意义”(201804010372)。

摘　　要：南海因受到高纬度气候、低纬度大洋以及东亚季风等多种因素的影响而成为研究古温度和季风变化的理想区域。本文通过研究QH-CL11柱状沉积物的GDGTs组成、含量变化特征及其延伸的86个碳原子的四醚指标(TEX86H),分析南海北部GDGTs来源,并定量计算QH-CL11柱状沉积物记录的海洋表面温度(SST),从而探讨31 ka以来南海北部古温度变化的驱动机制。通过甲烷指数和支链/异戊二烯类指标等,确定isoGDGTs主要来自于奇古菌,适用于古温度重建。TEX86H温度显示出明显的冰期一间冰期旋回,与南海北部有孔虫和UK’37 SSTs具有很好的相似性。出现在TEX86H SST中的海因里希冷事件(H1-3)和Bφlling-Allerod暖期之前的温度大幅度上升事件(14.6 ka)反映了高纬度气候对南海的影响。南海SSTs和北太平洋MD01-2421 UK’37SST的差异(△SST5)可以用来反映东亚冬季风强度的变化。△SSTs显示东亚冬季风强度在Bφlling-Allerφd暖期前增加,在新仙女木时期达到最大值,在全新世早期再次下降,然后在全新世中晚期缓慢增加,这与前人对东亚冬季风强度的认识具有很好的一致性。该方法对重建长周期东亚冬季风强度具有重要的指导意义。The South China Sea(SCS),under the control of multiple climate patterns,is an ideal region for studies of paleo-climate and the East Asian monsoon.In this paper,we studied the composition and characteristics of isoGDGTs to further identify their sources and used the outspread TEXH 86 index to reconstruct the sea surface temperature(SST)of the northern SCS for the past 31 ka quantificationally.By calculating the Methane Index and BIT indexes,we found that the isoGDGTs mainly came from Thaumarchaeota,and are suitable for TEXH 86 appliance.TEXH 86 temperatures exhibit distinct glacial–interglacial cycles,and is very similar to the SSTs from foraminifera and UK'37 in the northern SCS.TEXH 86 SSTs showed a decline trend during the Heinrich events(H1-3)and an abrupt rise at 14.6 kaBP before Bølling–Allerød(BA)warming,suggesting a tight climate teleconnection between the northern SCS and the North Atlantic region in last Deglaciation.The SST differences(ΔSSTs)between the SCS and the core MD01-2421 in the North Pacific was calculated and used to reveal the intensity of East Asian Winter monsoon.ΔSSTs showed that the EAWM intensity firstly increased before the BA warming,reached a maximum in the Younger Dryas period,decreased again in early Holocene and slowly increased in Late and Middle Holocene.TheΔSSTs results coincide with previous findings on the EAWM variations and constitute a feasible means of long-term EAWM intensity reconstruction.

关 键 词：异戊二烯甘油二烷基甘油四醚类 TEXH86 海洋表面温度 东亚冬季风强度 南海北部 

分 类 号：P736.4[天文地球—海洋地质]