大兴凸起北部D1钻孔岩心特征及第四纪地层划分

Core characteristics and stratigraphic classification of D1 borehole in the north of Daxing uplift

为了建立大兴凸起第四纪地层格架,对大兴凸起北部D1钻孔开展了地层划分、沉积相划分和年代地层的研究。将D1钻孔岩心自下而上划分为3套岩性组合,依次代表洪积扇沉积(186.6~203 m)、扇上河道沉积(153.9~186.6 m)、河流相沉积(0~153.9 m)。古地磁实验结果表明,古地磁极性带的布容正极性时、松山反极性时和高斯正极性时对应的钻孔岩心深度分别为0~89.5 m、89.5~132.25 m和132.25~143.5 m。结合岩性地层特征、^(14)C和OSL测年结果,得出D1钻孔下更新统(Qp 1)底界对应的深度为137.9 m,中更新统(Qp 2)底界对应的深度为91.4 m,上更新统(Qp 3)底界对应的深度为34.4 m,无全新世沉积。研究成果为该区第四纪区域地层划分和对比研究提供了基础资料。

In order to establish the Quaternary stratigraphic framework of Daxing uplift,We have studied the stratigraphic division,sedimentary facies and chronostratigraphy of the D1 borehole core in the north of Daxing uplift.The loose sediments of D1 can be divided into three lithological sections in this paper.The lithological sections were sedimentary environment of diluvial fan,braided river,the flood plain and riverbed,respectively.The results of the paleomagnetic test show that the polarity boundaries of B/M and M/G in D1 borehole are 89.5 m and 132.25 m.According to the magnetostratigraphy,combined with the lithostratigraphic property and ^(14)C dating data,we figured the boundaries of N/Q,Qp 1/Qp 2 and Qp 2/Qp 3 at the depth of 137.9 m,91.4 m and 34.4 m,respectively.The research results provide basic data for the division and correlation study of Quaternary regional strata in this area.