南黄海SYS90-1A孔第四纪沉积物磁性地层学研究  

Magnetostratigraphy of Quaternary sediments from borehole SYS90-1A in the South Yellow Sea

作　　者：陆凯 孙军[2,3,4] 李广雪 杨慧良[2,3] 王忠蕾[2,3] 梅西 陈晓辉 祁江豪[2,3] 朱晓青 强小科 LU Kai;SUN Jun;LI Guangxue;YANG Huiliang;WANG Zhonglei;MEI Xi;CHEN Xiaohui;QI Jianghao;ZHU Xiaoqing;QIANG Xiaoke(College of Marine Geosciences,Ocean University of China,Qingdao 266100,China;Qingdao Institute of Marine Geology,China Geological Survey,Qingdao 266237,China;Laboratory for Marine Mineral Resources,Laoshan Laboratory,Qingdao 266237,China;School of Ocean Sciences,China University of Geosciences(Beijing),Beijing 100083,China;State Key Laboratory of Loess and Quaternary Geology,Institute of Earth Environment,Chinese Academy of Sciences,Xi'an 710075,China)

机构地区：[1]中国海洋大学海洋地球科学学院,青岛266100 [2]中国地质调查局青岛海洋地质研究所,青岛266237 [3]崂山实验室海洋矿产资源评价与探测技术功能实验室,青岛266237 [4]中国地质大学(北京)海洋学院,北京100083 [5]黄土与第四纪地质国家重点实验室,中国科学院地球环境研究所,西安210008

出　　处：《海洋地质与第四纪地质》2024年第2期97-109,共13页Marine Geology & Quaternary Geology

基　　金：中国地质调查局地质调查项目“深海调查-测量”(DD20230643,DD20191003);“东部重点海域海洋区域地质调查”(DD20221710);“1:25万锦西、日照和霞浦县等图幅海洋区域地质调查”(DD20160139)。

摘　　要：可靠的年代地层框架是开展南黄海地区第四纪环境演变研究的基础。目前南黄海南部地区缺乏可靠年代学控制的长序列钻孔。通过对南黄海南部SYS90-1A孔(孔深90.1 m)沉积物开展详细的磁性地层学研究,并结合AMS14C测年结果及区域已有磁性地层学结果,建立南黄海南部地区第四纪沉积物年代地层框架。结果显示,SYS90-1A孔岩芯记录了从布容(Brunhes)正极性时至松山(Matuyama)负极性时上部,包括Kamikatsura和Santa Rosa地磁漂移事件。早、中更新世界线即布容正极性时与松山负极性时界线(B/M界线)深度位于74.2 m,Kamikatsura和Santa Rosa地磁漂移事件深度分别位于79.75~82.47 m和85.25~87.74 m。根据Kamikatsura和Santa Rosa地磁漂移事件的年代控制点和平均沉积速率,推算钻孔底部年龄为0.96 Ma。南黄海SYS90-1A孔早更新世晚期的沉积速率约为8.66 cm/ka,中更新世以来的沉积速率约为9.5 cm/ka,而全新世以来的沉积速率为12.8 cm/ka,沉积速率自早更新世晚期以来呈增加趋势。这一结果不仅为南黄海南部第四纪沉积物研究提供了有效的年代学约束,而且为南黄海地区第四纪地层划分和对比、沉积环境与气候变化、物源示踪等研究提供了重要的时间标尺。Quaternary sediments in the southern South Yellow Sea provide important geological archives for addressing Quaternary sea-level changes and environmental evolution.However,long sedimentary sequences with a reliable chrono-logical framework in this area are scarce.A detailed paleomagnetism study on sediments from borehole SYS90-1A(90.1 m)that located in the southern South Yellow Sea was carried out in combination with AMS14C dating data and published studies regarded.Eleven normal inclination zones and 11 negative inclination zones in the borehole SYS90-1A were revealed from the characteristic remanent magnetization after alternating-field demagnetization.The Matuyama/Brunhes boundary was found at the core depth of~74.2 m.Meanwhile,the Kamikatsura excursion and Santa Rosa excursion were recognized at depth of 79.75~82.47m and 85.25~87.74m,respectively.The basal age of the core was estimated for about 0.96 Ma by the extrapolation of average sedimentation rate between the Kamikatsura excursion and Santa Rosa excursion.The average sedimentation rate of borehole SYS90-1A is 8.66 cm/ka in the late Early Pleistocene,9.5 cm/ka since the Middle Pleistocene,and 12.8 cm/ka since the start of the Holocene.The sedimentation rate of the core showed an increasing trend since the late Early Pleistocene.This study provided a reliable geochronological framework of the borehole,which facilitated the stratigraphic division and tectonic evolution of the Quaternary System in the southern South Yellow Sea and its neighboring regions.

关 键 词：古地磁学 沉积速率 第四纪 中部泥质区 南黄海 

分 类 号：P736[天文地球—海洋地质]