东海外陆架厚层砂质沉积岩石磁学特征  

Rock-magnetic Properties of Thick Sandy Sediments on the Outer Continental Shelf of East China Sea

作　　者：刘建兴 石学法 吴永华 于晓晓 单新 徐涛玉 LIU Jian-xing;SHI Xue-fa;WU Yong-hua;YU Xiao-xiao;SHAN Xin;XU Tao-yu(First Institute of Oceanography,MNR,Qingdao 266061,China;Key Laboratory of Marine Geology and Metallogeny,MNR,Qingdao 266061,China;Laboratory for Marine Geology,Pilot National Laboratory for Marine Sciene and Technology(Qingdao),Qingdao 266237,China;Institute of Oceanography,Chinese Academy of Sciences,Qingdao 266071,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]自然资源部第一海洋研究所,山东青岛266061 [2]自然资源部海洋地质与成矿作用重点实验室,山东青岛266061 [3]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 [4]中国科学院海洋研究所,山东青岛266071 [5]中国科学院大学,北京100049

出　　处：《海洋科学进展》2020年第3期435-445,共11页Advances in Marine Science

基　　金：中央级公益性科研院所基本科研业务费专项资金资助项目——东海外陆架沉积岩石磁学与高分辨率磁性地层学研究(2016Q06);晚第四纪水下长江三角洲沉积构型及其对气候、海平面变化响应机理研究(2017Q08);国家自然科学基金项目——东海外陆架磁性地层年代框架的建立及其古环境意义(41606075);东海外陆架晚第四纪高精度年代地层及层序地层研究(41406051);海洋地质过程与环境(U1606401)。

摘　　要：对位于东海外陆架潮流沙脊分布区的DH03孔(进尺101.6 m,水深96 m)上部0~48 m层位的砂质沉积样品进行了岩石磁学测试分析。研究结果表明:砂质沉积物中的主要磁性组分为陆源碎屑型磁铁矿(Fe3O4),并含有少量赤铁矿(Fe2O3);不同层位沉积物中的磁性矿物的粒径差别非常显著,几乎涵盖从单畴(SD)、准单畴(PSD)乃至多畴(MD)的各种磁畴状态,不利于相对古强度(RPI)的应用,这与研究区复杂多变的水动力过程和物质来源密切相关;同时,部分层位沉积物中原生的铁氧化物特别是磁铁矿已经发生了一定程度的成岩改造,形成了少量的自生胶黄铁矿(Fe3S4),指示了较高的有机碳供应和沉积速率;此外,磁性矿物含量随深度变化也较为明显。揭示了东海外陆架砂质沉积物中磁性矿物的复杂性。Systematically rock magnetic analyses have been conducted on the sandy sediments from the upper 0~48 m section of core DH03 that was recovered from the tidal sand-ridge on the outer shelf of the East China Sea.The studied core has a whole drilling length and water depth of 101.6 m and 96 m,respectively.Our data indicate that the major magnetic component in the studied sediments is terrigenous detrital magnetite(Fe3O4)with trace of hematite(Fe2O3).The grain sizes of magnetic minerals differ remarkably and almost contain all magnetic domains including the single domain(SD),pseudo-single domain(PSD),and multiple domain(MD),which impedes the application of relative paleointensity(RPI)and implies the complexities of provennces and hydrodynamic processes.Meanwhile,the primary iron oxides,especially magnetite in some layers have been altered by diagenesis,resulting in formation of a little of authigenic greigite(Fe3S4),which indicates high organic carbon as well as sedimentation rates.In addition,the variations of magnetic mineral content along depths are also relatively evident.In brief,this study reveals the rock magnetic complexity of the sandy sediments on the outer shelf of the East China Sea.

关 键 词：东海 外陆架 潮流沙脊 岩石磁学 磁铁矿 胶黄铁矿 

分 类 号：P736[天文地球—海洋地质]