北京怀柔HR_（88－1）钻孔剖面磁性地层学研究  

On magnetostratigraphy of the borehole HR_(88-1) in Huairou area, Beijing

作　　者：李龙吟[1] 陈华慧[1] 

机构地区：[1]中国地质大学

出　　处：《地层学杂志》1994年第1期39-44,共6页Journal of Stratigraphy

摘　　要：在系统古地磁样品采集、处理和测量的基础上，运用磁性地层学的研究方法，对北京怀柔地区ＨＲ（８８－１）钻孔剖面进行了详细地层划分，分别确定了该区上新统、下更新统、中更新统和上更新统的分布深度及地质年代。In order to give a systematic layering and determination of geological time to the borehole sequence, a sampling was made for palaeomagnetic dating with an average interval of 1.2-1.3m. By thermal demagnetization, 1137 geomagnetic element data were extracted from 400 original samples, comprehensive analyses on the data have resulted in a polarity column shown in Figure 4.As can be seen, the polarity column is evidently divisible into three members.The interval from the surface down to 142m depth represents the Brunhes normal polarity chron, which involves two reversed polarity subchrons corresponding to the depth of 16-18m and 33-36m. A C14 age of 19 580a obtained from the sample at the depth of 8.35m and two thermoluminescent datings of 69 500a and 102 000a respectively from the samples of 27m and 32m deep demonstrate that the above mentioned two reversed subchrons are equivalent to the Laschamp subchron and Black subThe range from 142 to 358.5m deep corresponds to the Matuyama reversed polarity chron, this chron was interrupted by two normal subchrons: the Jaramillo (172-185m) and Olduvai (279-304m), as evidenced by a comparative analysis.The Gauss normal polarity chron is shown from 358.5 to 505.27m deep in theborehole. It embraces a reversed subchron, the Kaena, limited within the interval of454-475m deep.The lithologic section of the borehole HR, includes the entire Pleistocene series and part of Pliocene series. According to the correlation of the polarity columnand the lithologic section, we believe that the sediments below 370m depth belongto the Upper Pliocene series which cover a time span of 2.48--3.0Ma. The LowerPleistocene Series ranges from the depth of 145--370m. which was formed during0.73--2.48Ma. The Middle and Upper Pleistocene Series correspond to the Brunhesnormal polarity chron. The time boundary between Middle and Upper Pleistocene Series is about 0.15Ma. Our definition for the N/Q boundary is approximately conformable with M/G boundary.

关 键 词：古地磁 磁性地层学 第四纪 北京 

分 类 号：P534.63[天文地球—第四纪地质学]