渤海BH08孔磁学参数变化机制与环境指示  

Variations of magnetic proxies in core BH08from Bohai Sea and its environmental implications

作　　者：董靓雯 姚政权[3,4] 石学法 姜兆霞[4,5] 刘青松 DONG JingWen;YAO ZhengQuan;SHI XueFa;JIANG ZhaoXia;LIU QingSong(Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;University of Chinese Academy of Sciences,Beijing 100049,China;Key Laboratory of Marine Sedimentology and Environmental Geology,First Institute of Oceanography,State Oceanic Administration,Qingdao 266061,China;Laboratory for Marine Geology and Environment,National Laboratory for Marine Science and Technology,Qingdao 266237,China;Key Lab of Submarine Geosciences and Prospecting Techniques,MOE,College of Marine Geosciences,Ocean University of China,Qingdao 266100,China;Department of Marine Science and Engineering,Southern University of Science and Technology,Shenzhen 518055,China)

机构地区：[1]中国科学院地质与地球物理研究所,北京100029 [2]中国科学院大学,北京100049 [3]海洋沉积与环境地质国家海洋局重点实验室,国家海洋局第一海洋研究所,青岛266061 [4]青岛海洋科学与技术国家实验室海洋地质过程与环境功能实验室,青岛266237 [5]中国海洋大学海洋地球科学学院,海底科学与探测技术教育部重点实验室,青岛266100 [6]南方科技大学海洋科学与工程系,深圳518055

出　　处：《地球物理学报》2018年第11期4530-4544,共15页Chinese Journal of Geophysics

基　　金：国家重点研发计划(2016YFA0601903);国家自然科学基金重点项目(41430962);国家基金委-山东省联合基金项目(U1606401);亚洲大陆边缘项目(GASI-GEOGE-03)资助.

摘　　要：边缘海-陆架区是研究海陆交互作用的理想区域,该区沉积物记录了海平面、气候与构造变化的重要信息.渤海作为我国的内海,前人对该区虽然进行了环境磁学方面的研究,但是受复杂的沉积环境影响,渤海沉积物的磁性变化机制十分复杂,因而需要对该区沉积物磁学性质及变化机制进行深入研究.针对这一问题,本文详细研究了渤海BH08孔岩芯沉积物的磁学性质,结果表明:①沉积物中主要载磁矿物是磁铁矿,部分层位含有高矫顽力的矿物;②岩芯整体磁学性质变化复杂,各项磁学参数变化剧烈,其总体波动与S/Cl值、沉积物红度a~*和深海底栖有孔虫δ^(18)O相关性较好;③在主要的海陆交替边界层位发现胶黄铁矿,表明是富硫的弱还原环境,而快速变化的沉积环境和较高的沉积速率是胶黄铁矿得以保存的重要因素,因而胶黄铁矿可作为沉积环境发生转变的一种特征矿物.这些新认识为深入开展渤海地区,乃至陆架-边缘海区古环境研究提供了新的思路和方法.Marginal sea is an ideal area for studying the interaction of ocean and continent,and its sediment has recorded valuable information of climate and tectonic change.As an important part of Chinese marginal sea,previous researchers have systematically conducted magnetic and paleoclimatic studies on sediments of the Bohai Sea.However,due to complex environmental influences,the magnetic variation mechanism of the Bohai sediments is complicated.In this paper,we study magnetic properties of BH08 core sediments from the Bohai Sea.The core BH08 was drilled to a depth of 212.4 m in the central Bohai Sea with water depth of^25 m.Magnetic measurements were carried out on selected samples,mainly including the magnetic susceptibility(,mass-specific),hysteresis loop,acquisition curve of isothermal remanent magnetization(IRM),the first-order reversal curve(FORC)diagram,temperature dependent curves of magnetic susceptibility(-T curve)and low-temperature remanent magnetization curves.Results indicate:1)the main magnetic minerals in sediments are magnetite and greigite,along with some high coercivity minerals such as hematite;2)magnetic variations are complicated,and are controlled mainly by the fluctuation of sea level according to the correlation between magnetic parameters and S/Cl value,redness(a*)andδ18 O;3)greigite has been spotted in some layers,which indicates rapid changes in the depositional environment.Based on the high resolution chronology from Yao et al.(2014),we discussed the variation mechanism for magnetic proxies and its environmental implications,which are significant for the following environmental studies in the area.

关 键 词：渤海 BH08孔 磁性矿物 环境磁学 海平面 

分 类 号：P736[天文地球—海洋地质] P318[天文地球—海洋科学]