西南印度洋中脊轴部裂谷(49.58°E)沉积物岩心地球化学特征及物源  

Geochemistry and provenance of the sediment core from the rift valley of the Southwest Indian Ridge(49.58°E)

作　　者：黄永金 陶春辉 梁锦 廖时理 杨伟芳 HUANG Yongjin;TAO Chunhui;LIANG Jin;LIAO Shili;YANG Weifang(Second Institute of Oceanography,Ministry of Natural Resources,Hangzhou 310012,Zhejiang,China;Key Laboratory of Submarine Geosciences,Ministry of Natural Resources,Hangzhou 310012,Zhejiang,China;School of Oceanography,Shanghai Jiao Tong University,Shanghai 200030,China)

机构地区：[1]自然资源部第二海洋研究所,浙江杭州310012 [2]自然资源部海底科学重点实验室,浙江杭州310012 [3]上海交通大学海洋学院,上海200030

出　　处：《地质通报》2021年第2期320-329,共10页Geological Bulletin of China

基　　金：国家重点研发计划项目《蛟龙号载人潜水器在热液区的科学应用》(编号:2017YFC0306603);国家自然科学青年基金项目《西南印度洋龙旂矿化区烟囱体形成过程重构:来自微区元素和同位素的信息》(批准号:41806076);自然资源部第二海洋研究所基本科研业务专项《西南印度洋脊龙旂热液区枝状硫化物烟囱体的形成机制研究》(编号:JG1905);大洋“十三五”资源环境专项《多金属硫化物合同区资源勘探与评价》(编号:DY135-S1-1-02、DY135-S1-1-08、DY135-S1-1-09)。

摘　　要：目前有关西南印度洋中脊沉积物的研究多集中在洋脊翼表层沉积物,对洋脊轴部裂谷沉积物的研究较匮乏,制约了对该区沉积物物质来源和沉积环境的深入认识。针对大洋49航次在洋脊轴部裂谷(东经49.58°)获取的沉积物岩心(GC03)进行了全岩样品主量、微量、稀土元素和Y(REY)含量测试分析,探讨研究区沉积物的物质来源和沉积环境。结果表明,GC03岩心样品富Ca O、LOI(烧失量)和Sr,指示以钙质生物沉积占主导,并混有玄武岩碎屑。稀土元素总量(ΣREY)低,平均为54.3×10-6,稀土元素球粒陨石标准化配分图显示轻稀土元素富集,Ce和Eu显著负异常特征。其中L2层(83~87 cmbsf)富集Cu、Zn、Fe、Co等金属元素及较低的100*Al/(Al+Fe+Mn)值,揭示存在热液组分输入。Ceanom值与微量元素V/(V+Ni)-U/Th判别指标指示,研究区总体为偏氧化环境,部分层位显示还原特征。The current research on the sediments of the Southwest Indian Ridge(SWIR)mainly focuses on the surface sediments of the flank of the ridge,but lack of research on its ridge axis restricts the in-depth understanding of the sediment sources and sedimentary environment in this area.Based on the major element,trace element,REE and Y assay of a sediment core(GC03)collected from SWIR 49.58°E during Chinese DY-49 Cruise,the material source and sedimentary environment of the sediments in the study area were discussed.The results show that the bulk samples are enriched in CaO,LOI and Sr,indicating that calcareous biodeposition is dominant and mixed with basalt debris.The content of theΣREY is low,with average value of 54.3×10-6,and the chondrite-nomalized REY distribution patterns show the enrichment of LREE compared to HREE and significant negative Ce and Eu anomaly.The enrichment of metal elements such as Cu、Zn、Fe and Co,and low 100*Al/(Al+Fe+Mn)value characterizing samples from Layer L2(83-87 cmbsf)reveals the presence of a hydrothermal component input.The Ce anom value and V/(V+Ni)-U/Th discriminant diagram indicate that the study area is generally a stable oxidized environment except for reduction characteristics exhibited from partial samples.

关 键 词：西南印度洋中脊 沉积物岩心 地球化学 物质来源 沉积环境 

分 类 号：P736.21[天文地球—海洋地质] P59[天文地球—海洋科学]