冲绳海槽南段沉积物的元素赋存状态及其热液活动记录  

States of element occurrence of sediments in the southern Okinawa Trough and its hydrothermal activity

作　　者：叶凡凡 曾志刚[2,3,4,5] YE Fanfan;ZENG Zhigang(Shandong University of Science and Technology,Qingdao 266590,China;Institute of Oceanology,Chinese Academy of Sciences,Qingdao 266071,China;CAS Key Laboratory of Marine Geology and Environment,Institute of Oceanology,Chinese Academy of Sciences,Qingdao 266071,China;Laboratory for Mineral Resources,National Laboratory for Marine Science and Technology(Qingdao),Qingdao 266237,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]山东科技大学地球科学与工程学院,青岛266590 [2]中国科学院海洋研究所,青岛266071 [3]中国科学院海洋地质与环境重点实验室,青岛266071 [4]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266237 [5]中国科学院大学,北京100049

出　　处：《海洋地质与第四纪地质》2023年第5期160-172,共13页Marine Geology & Quaternary Geology

基　　金：国家自然科学基金“西太平洋俯冲体系中岩浆活动及其对热液物质供给的制约”(91958213);中国科学院战略性先导科技专项“热液/冷泉区岩浆物质贡献与流体化学过程”(XDB42020402);国家重点基础研究发展计划(973计划)项目“典型弧后盆地热液活动及其成矿机理”(2013CB429700);泰山学者工程专项(ts201511061)。

摘　　要：为了解冲绳海槽南部沉积物的元素赋存状态以及热液活动对沉积物中元素组成的影响,对冲绳海槽南部沉积物岩芯HOBAB4-S2进行了全岩样及顺序提取分析,探讨了该沉积物岩芯中Al、Ti、K、Fe、Mn、Cu、Zn、Pb、Co、Ni及稀土元素的赋存状态,结果表明残留相与碳酸盐相是岩芯沉积物中元素的重要赋存形式,典型的碎屑组分Al、K、Ti在残留相中比例极高。铁锰氧化物相和有机结合相中各元素含量均相对较低,但在铁锰氧化物相中,与热液活动相关的金属元素在岩芯的萃取比例及含量上随着深度变化具有一致性,同时在4个层位出现了异常高值,表明在该层位对应的时期出现了热液活动对元素组成的显著影响,稀土元素总量变化上也可看出明显相同的变化趋势。沉积物的球粒陨石标准化稀土元素配分模式整体显示了轻稀土元素相对重稀土元素更富集的特征,具有极其轻微的Ce正异常和明显的Eu负异常,与南大西洋受热液活动影响较小的沉积物中铁锰氧化物相的配分模式类似,表明其受到热液流体的影响,是铁锰颗粒吸附海水与热液流体中稀土元素的结果。To understand the element occurrence states of sediments in the southern Okinawa Trough and the influence of hydrothermal activity on the elemental composition of the sediments,the whole-sample and sequential extraction of core HOBAB4-S2 from the southern Okinawa Trough were analyzed and the occurrence state of Al,Ti,K,Fe,Mn,Cu,Zn,Pb,Co,Ni,and rare earth elements in the sediment core.The results show that the residual phase and carbonate phase are the important forms of elements in the sediments,and the typical clastic components Al,K,and Ti have a high proportion in the residual phase.The contents of elements in Fe-Mn oxide and organic bound phases are relatively low,but in the Fe-Mn oxide phase,the extraction rates and contents of metallic elements associated with hydrothermal activity in the cores are consistent with depth,and anomalously high values appear in four layers,indicating that the significant influence of hydrothermal activity on elemental compositions occurred in the corresponding period of the layer.The same trend can be seen in the total amount of rare earth elements.The chondrite-normalized rare earth element distribution patterns of the sediments show evidence of light rare earth element enrichment relative to heavy rare earth elements,with very small positive Ce anomalies and obvious negative Eu anomalies.The case is similar to the distribution pattern of the Fe-Mn oxide phase of the sediments in the South Atlantic Ocean,showing that it was less affected by hydrothermal activity,but affected by hydrothermal fluids,which is the result of rare earth elements absorption by Fe-Mn particles in seawater and hydrothermal fluids.

关 键 词：沉积物 顺序提取 元素赋存状态 热液活动 冲绳海槽 

分 类 号：P736.21[天文地球—海洋地质]