氧同位素3早期以来千年尺度气候事件在日本海北部的磁学记录  

Magnetic recordings of millennium-scale climate events in the northern Japan Sea since the early MIS 3

作　　者：邹庆超 石学法 葛淑兰 吴永华 邹建军 贺湘锋 Sergey A.Gorbarenko 刘建兴 Zou Qingchao;Shi Xuefa;Ge Shulan;Wu Yonghua;Zou Jianjun;He Xiangfeng;Sergey A.Gorbarenko;Liu Jianxing(Key Laboratory of Marine Geology and Metallogeny,First Institute of Oceanography,Ministry of Natural Resources,Qingdao 266061,China;Laboratory of Marine Geology,Qingdao Marine Science and Technology Center,Qingdao 266237,China;School of Geography and Marine Science,Nanjing University,Nanjing 210023,China;Institute of Pacific Ocean Research,Far Eastern Branch of Russian Academy of Sciences,Vladivostok 690041,Russia)

机构地区：[1]自然资源部第一海洋研究所海洋地质与成矿作用自然资源部重点实验室,山东青岛266061 [2]青岛海洋科技中心海洋地质过程与环境功能实验室,山东青岛266237 [3]南京大学地理与海洋科学学院,江苏南京210023 [4]俄罗斯科学院远东分院太平洋研究所,俄罗斯符拉迪沃斯托克690041

出　　处：《海洋学报》2024年第4期106-121,共16页

基　　金：中央级公益科研院所基本科研业务费专项项目(2021S01);国家自然科学基金项目(U1606401,41976078)。

摘　　要：日本海是西北太平洋最大的边缘海,长期以来普遍认为其沉积物处于强烈的还原环境中而导致相应的磁学信号非常微弱,以致常用的磁学方法在该区的应用一直受限。为深入探讨磁学指标在日本海古环境与古海洋学研究中是否有效,本文对位于研究程度相对薄弱的北部一根626 cm长的柱状沉积物岩心(LV87-2-3孔,水深740 m)开展了系统的岩石磁学测试分析以及高分辨率的AMS14C测年和粒度分析。结果显示岩心系约48.3 ka BP以来的沉积记录,其55 cm以下层位的原生亚铁磁性矿物(主要为磁铁矿)已被大量还原而生成黄铁矿,导致磁性极弱。这与Dansgaard-Oeschger(D-O)旋回间冰阶水体分层加强和表层生产力提高等因素密切相关。然而,在此背景下仍存在4个以高矫顽力矿物(如赤铁矿和针铁矿)占比较高为明显特征的强磁性层位,即“硬磁异常”层;其很好地对应了海因里希(Heinrich)事件,指示了东亚冬季风(EAWM)增强和高盐度对马暖流(TWC)注入而导致的相对减弱的还原环境。上述变化在沉积物粒度上却未见清晰体现。因此,该研究不仅表明磁学参数对于指示末次冰期日本海古海洋与古环境演化的作用不容忽视,同时也为后续相关工作提供了新视角和新思路。The Japan Sea is the largest marginal sea in the northwestern Pacific Ocean.For a long time,it has been widely believed that the sediments are deposited in strongly reducing environment,which results in extremely weak magnetic signals and then restricts the application of frequently-used magnetic method in this region.To investigate deeply the availability of magnetic indicators in paleoenvironmental and paleoceanographic studiesin the Japan Sea,we conducted systematic rock magnetic analyses,high-resolution accelerator mass spectrometer(AMS) 14C dating,and grain-size analysis on a 626-cm-long sediment core(LV87-2-3,water depth 740 m) recovered from the northern Japan Sea that has been studied in relatively low level.The results indicate that the studied core corresponds to a sedimentary record since approximately 48.3 ka BP.The majority of primary ferrimagnetic minerals,mainly magnetite,in the sediments below 55 cm,had been reduced into pyrite,which caused weakly magnetic intensity.This is associated closely with the intensified stratification of water body and the increase in surface productivity during interstadials in the Dansgaard-Oeschger(D-O) cycles.Nevertheless,there are still four strong magneticlayers characterized by elevated percentages of high-coercivity minerals(i.e.,hematite and goethite),which are termed as ‘hard-magnetic abnormal' layers and correspond well with the Heinrich Events.This indicatesrelatively weak reducing conditions that were resulted from the enhanced East Asian Winter Monsoon(EAWM) and injection of high salinity Tsushima Warm Current(TWC).These changes,however,are not reflected by the grain-size of sediment.Our study therefore not only indicates that the role of magnetic parameters in the paleoenvironmental and palaeoceanographic reconstructions of the Japan Sea during the last glacial,but also provides new perspectives and ideasfor relevant investigations in the future.

关 键 词：日本海沉积物 磁性矿物 岩石磁学 古环境 HEINRICH事件 

分 类 号：P736.3[天文地球—海洋地质]