南海冰期陆架风化与碳循环  

South China Sea shelf weathering in glacial periods and its link to carbon cycle

作　　者：万世明[1,2] 秦琳 杨守业 赵德博[1] 张晋[1] 矫东风[5] 蔡观强[6] 裴文强[1] 龚红梅[1] 徐兆凯[1] 黄杰[1] 于兆杰[1] 靳华龙 李安春 李铁刚[7] Wan Shiming;Qin Lin;Yang Shouye;Zhao Debo;Zhang Jin;Jiao Dongfeng;Cai Guanqiang;Pei Wenqiang;Gong Hongmei;Xu Zhaokai;Huang Jie;Yu Zhaojie;Jin Hualong;Li Anchun;Li Tiegang(Key Laboratory of Marine Geology and Environment,Institute of Oceanology,Chinese Academy of Sciences,Qingdao 266071,Shandong;Laboratory for Marine Geology,Pilot National Laboratory for Marine Science and Technology(Qingdao),Qingdao 266237,Shandong;University of Chinese Academy of Sciences,Beijing 100049;State Key Laboratory of Marine Geology,Tongji University,Shanghai 200092;Hainan Marine Geological Survey and Research Institute,Haikou 570206,Hainan;Guangzhou Marine Geological Survey,Guangzhou 510760,Guangdong;Key Laboratory of Marine Sedimentology and Environmental Geology,First Institute of Oceanography,Ministry of Natural Resources,Qingdao 266061,Shandong)

机构地区：[1]中国科学院海洋研究所,中国科学院海洋地质与环境重点实验室,山东青岛266071 [2]青岛海洋科学与技术试点国家实验室,海洋地质过程与环境功能实验室,山东青岛266237 [3]中国科学院大学,北京100049 [4]同济大学海洋地质国家重点实验室,上海200092 [5]海南省海洋地质调查研究院,海南岛海口570206 [6]广州海洋地质调查局,广东广州510760 [7]自然资源部第一海洋研究所,海洋沉积与环境地质国家海洋局重点实验室,山东青岛266061

出　　处：《第四纪研究》2020年第6期1532-1549,共18页Quaternary Sciences

基　　金：国家自然科学优秀青年基金项目(批准号:41622603);中国科学院(B类)战略性科技先导专项项目(批准号:XDB40010100);"科学"号高端用户项目(批准号:KEXUE2017G15);泰山学者和鳌山人才计划项目(批准号:2017ASTCP-ES01)共同资助。

摘　　要：第四纪冰期-间冰期旋回中大气CO2浓度周期性演变的过程和机制是国际学术界长期争论的前沿科学问题。迄今研究大多强调大洋深部过程的调控,忽略了冰期-间冰期时间尺度上海平面巨大变化所引起的陆架风化的反馈作用。本研究基于末次冰盛期以来海南岛万泉河口、珠江口、台湾浊水溪口和南海北部台西南盆地4根岩芯沉积物粘土粒级组分的钕同位素和粘土矿物组成的分析,开展了南海及全球其他地区的风化和气候记录对比。南海西侧的东亚大陆化学风化强度在全新世明显高于末次冰盛期-冰消期,突显了末次冰期以来大陆风化演变的季风驱动;台湾则呈现较为稳定的化学风化模式,反映了高侵蚀速率条件下受限制的化学风化。台西南盆地的沉积物源持续来自台湾岛,显示出冰期的化学风化强度比全新世增强近1倍。类似记录在南海北部和南部陆坡-海盆,甚至西菲律宾海都有发现,推测为冰期低海平面时期陆架暴露风化增强所致。本研究表明,冰期热带陆架硅酸盐风化是影响冰期-间冰期碳循环的一个不可忽略的重要机制。The process and mechanism of periodic evolution of atmospheric CO2 concentration in the Quaternary glacial-interglacial cycles have been the frontier research topic in Earth Science in recent years.Until now,most studies emphasize the modulation by processes in the deep ocean,however,the feedback of shelf weathering exposed during glacial lowstands remains unclear.Here we analyzed the Nd isotopic and clay mineral compositions of clay-sized sediments of 4 sediment cores,including core ZK001(19°16.8'N,110°47.4'E;water depth 36.9 m;23.7 m in length and since 17.2 ka B.P.)offshore from eastern Hainan,core ZK20(22°17'N,113°51'E;water depth 5.7 m;14.3 m in length and since 10.5 ka B.P.)from the Pearl River mouth,borehole JRD-S(23°49.9'N,120°14.4'E;4.1 m above sea level;58.0 m in length and since 21.0 ka B.P.)from the Zhuoshui River mouth of SW Taiwan and core TWS-1(22°06'N,119°17'E;water depth 1186 m;6.29 m in length and since 22.7 ka B.P.)from the northern South China Sea,in order to study the silicate weathering and its link to climate change since the Last Glaciation Maximum(LGM).Our data show stronger chemical weathering intensity of East Asian continent to the west of South China Sea in the Holocene than the LGM-last deglacial,suggesting its monsoonal climate forcing.In contrast,Taiwan displays stable chemical weathering since LGM,indicating limited weathering under conditions of extreme high physical erosion.The sediment source of the studied site in the Taixinan Basin in the northeastern South China Sea is stably supplied from Taiwan island since the LGM.The clay mineral proxy shows one fold strengthened chemical weathering during glacial than the Holocene.Similar records were also observed from the slope to basin of both northern and southern South China Sea,and even the west Philippine Sea,suggesting subaerial exposure and weathering of unconsolidated shelf sediments during glacial sealevel lowstands.Our study suggests that enhanced silicate weathering of tropical shelf sediments exposed during glacial

关 键 词：南海 热带陆架 化学风化 粘土矿物 冰期-间冰期 碳循环 

分 类 号：P532[天文地球—古生物学与地层学] P595[天文地球—地质学]