北部湾中东部全新世沉积地球化学特征及其指示意义  

Holocene sedimentary geochemical characteristics of the mid-eastern part of the Beibu Gulf and their implications

作　　者：周国议 曹新星 夏嘉 宋之光[1,2] ZHOU Guoyi;CAO Xinxing;XIA Jia;SONG Zhiguang(State Key Laboratory of Organic Geochemistry,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,Guangdong,China;CAS Center for Excellence in Deep Earth Science,Guangzhou 510640,Guangdong,China;University of Chinese Academy of Sciences,Beijing 100049,China;Key Laboratory of Beibu Gulf Environmental Change and Resources Utilization of Ministry of Education,Nanning Normal University,Nanning 530001,Guangxi,China;College of Chemistry and Environmental Science,Guangdong Ocean University,Zhanjiang 524088,Guangdong,China)

机构地区：[1]中国科学院广州地球化学研究所,有机地球化学国家重点实验室,广东广州510640 [2]中国科学院深地科学卓越创新中心,广东广州510640 [3]中国科学院大学,北京100049 [4]南宁师范大学北部湾环境演变与资源利用教育部重点实验室,广西南宁530001 [5]广东海洋大学化学与环境学院,广东湛江524088

出　　处：《地球化学》2024年第5期745-759,共15页Geochimica

基　　金：中国科学院广州地球化学研究所有机地球化学国家重点实验室开放基金项目(SKLOG2020-2);广西科技基地与人才专项(桂科AD20238087);国家自然科学基金项目(41773037)联合资助。

摘　　要：通过分析测定南海北部湾中东部海底柱状沉积物的主量、微量元素和矿物组成,结合AMS^(14)C定年,研究了11.3 ka BP以来该海域全新世沉积地球化学特征及其对物源和海洋环境变化的指示意义。结果表明,剖面以86 cm为界限,大部分主量、微量元素含量呈现明显的上、下两阶段变化特征,分别为3.2~0.2 ka BP的上部沉积层段(86~4 cm)和11.3~3.2 ka BP的下部沉积层段(200~86 cm),其中Si、Ca、Zr等元素含量在上部层段沉积物中显著减少,而A1、Fe、Ti、V、Cr、Co等元素含量明显升高,稀土元素含量变化不明显。此外,剖面中的矿物组成主要为石英、伊利石、绿泥石和长石。相比于下部层段,上部层段中绿泥石含量更高、长石含量更低。综合来看,沉积物物源输入比较稳定,主要来自周边海岸侵蚀产物和琼州海峡的下切侵蚀产物,其次是红河和珠江携带的沉积物。剖面上、下层段沉积物中元素和矿物含量的差异主要与3.2 ka BP以来,高海平面下琼州海峡进一步扩张引起的海底下沉和海水深度增加有关,从而导致上部沉积时期水动力较弱,黏土矿物含量增加。In this paper,the sedimentary geochemical characteristics of the mid-eastern Beibu Gulf of the South China Sea and their implications for sediment sources and marine environmental change since 11.3 ka BP were studied by determining the major and trace elements and mineral compositions of the seafloor sediment core,combined with AMS 14C dating.The results indicate that the contents of most of main and trace elements in the sediment core change obviously at the 86 cm boundary.The upper section sediments(86 to 4 cm,3.2 to 0.2 ka BP)have lower Si,Ca,and Zr contents and higher Al,Fe,Ti,P,V,Cr,and Co contents higher than those of the lower section sediments(200 to 86 cm,11.3 to 3.2 ka BP).However,no obvious changes of rare earth element contents were detected in the whole core.The main minerals of the sediment core include quartz,illite,chlorite,and feldspar,however,the upper section sediments are relatively chlorite rich and feldspar poor.It can be inferred that the sediment provenance area did not change significantly,and the overall sediment input was relatively stable,mainly from the erosion of the surrounding coast and the Qiongzhou Strait,followed by the sediment carried by the Red River and the Pearl River.The differences in abundances of elements and minerals between the upper and lower section sediments are mainly attributed to the further expansion of the Qiongzhou Strait since 3.2 ka BP,caused by seafloor subsidence and the increase in seawater depth at high sea level,which leads to the weakening of hydrodynamic forces and an increase in the clay mineral content.

关 键 词：沉积柱 元素组成 矿物组成 海洋环境变化 北部湾 

分 类 号：P593[天文地球—地球化学] P597[天文地球—地质学]