The response relationship between the variation characteristics of deposition rate of Quaternary depression basin on the northern margin of Beijing depression and the activity of Shunyi fault

Controlled by both Huangzhuang-Gaoliying fault and Nanyuan-Tongxian fault, Beijing depression was formed in the Tertiary period. The northern margin of Beijing depression in Quaternary disintegrated due to the strong activity of the Shunyi fault, and formed two new depressions, i.e., Houshayu depression and Fengbo depression. In this study, the authors conducted the research on Quaternary magnetic strata in drill hole ZK19. In combination with the OSL results, the bottom depths of early Pleistocene, Middle Pleistocene, late Pleistocene and Holocene strata in drill hole ZK19 were determined, which are 434 m, 128 m, 29.9 m and 1.35 m respectively. By comparative analysis of the sedimentary thickness and deposition rate of drill hole ZK12-2 in Fengbo depression, the authors investigated the Shunyi fault activity characteristics since the Quaternary, and discussed the evolution of the basin on the northern margin of Beijing depression. The results show that the intense activity of Shunyi fault in the early Pleistocene resulted in the disintegration of the basin on the northern margin of Beijing depression. In the Middle Pleistocene, the activity of Shunyi fault was indistinct relative to Huangzhuang-Gaoliying fault. In the late Pleistocene, Shunyi fault had a strong activity again relative to Huangzhuang-Gaoliying fault, which accelerated the disintegration of the basin on the northern margin of Beijing depression. In the Holocene, the strong activity of Shunyi fault caused the growth of ground fissures and the destruction of buildings.