摘要
对渤海湾西岸孔深503.22m的CH500孔进行了详细的磁性地层学研究,基于377个交变退磁样品分离出的特征剩磁,建立了钻孔的磁性地层,并与标准极性年表相对比,确定了极性时和极性亚时,在此基础上探讨了该孔年代地层划分及其区域构造意义。结果表明:本钻孔B/M界限深度119.5m,M/G界限深度为359.1m,钻孔底部位于C2An.2r内,其年龄应小于3.33 Ma。通过与渤海湾西北岸的其他钻孔对比,发现各钻孔的B/M界限深度和M/G界限深度存在较大的不同,反映了不同的级次构造单元地层厚度的差异。这一研究为该钻孔提供了可靠的年代标尺,为渤海湾西岸第四系地层划分和对比提供了新的依据。
Magnetostratigraphic studies have been conducted for the 377 samples taking from the borehole of CH500（503.22m）on the western coast of the Bohai Bay.Based on the alternating demagnetization results of the specimens and compared them to the geomagnetic polarity timescale,we calculated the characteristic directions of remanent magnetization and clarified the polarity of each samples.A stratigraphic classification was then established and the tectonic significance of the borehole discussed.The Brunhes/Matuyama boundary was found at the core depth of 119.5m,and the Matuyama/Gauss boundary at the core depth of 359.1m.The age of the hole bottom is supposed to be less than 3.33 Ma.Comparing with other boreholes in the west and north coasts of the Bohai Bay,it is found that the depths of both the B/M and M/G boundary change from place to place are dependent upon the stratigraphic thickness of the deposits in different tectonic units.The results have not only provided a reliable chronological framework for the borehole CH500,but also facilitated a Quaternary stratigraphic framework for the western coast of the Bohai Bay.
出处
《海洋地质与第四纪地质》
CAS
CSCD
北大核心
2016年第4期19-28,共10页
Marine Geology & Quaternary Geology
基金
中国地质调查"天津滨海新区地质环境调查评价(1212011120089)"项目
关键词
磁性地层学
沉积速率
构造活动
渤海湾西岸
magnetostratigraphy
sedimentation rate
tectonics
the Western Coast of Bohai Bay
