Quaternary magnetic stratigraphy and its sedimentary response to new tectonic movement in Shahe depression, plain area of Beijing

The tectonic pattern of Beijing area in Tertiary was"two uplifts and one depression". Due to the strong activity of the north part of Sunhe fault since the Quaternary period, new Quaternary depression basin, i.e., Shahe depression, was separated from the above pattern. The authors conducted research on Quaternary magnetic stratigraphy of drill hole ZK3 in Shahe depression. In combination with the 14C isotopic dating results, the authors obtained the depth of the bottom of the strata in early Pleistocene, Middle Pleistocene, late Pleistocene and Holocene, being 439.8 m, 157.4 m, 87.7 m and 7.2 m respectively. On such a basis, the authors established the Quaternary stratigraphic sequence of drill hole profile. The Quaternary deposition rates were 0.19 mm/a, 0.11 mm/a, 0.70 mm/a and 0.63 mm/a. A comparative analysis of the activity regularity of the basin- controlling fault, i.e., Nankou- Sunhe fault, and characteristics of Beijing Xishan (Western Hills) uplift shows that since the Quaternary period, influenced by Beijing Xishan uplift, the contemporaneous faults that controlled Shahe depression, i.e., Nankou Sunhe faults, activated strongly, and controlled the evolution of Shahe depression. The variation rule of average deposition rate of the strata in the drill hole, the mountain uplift rate and the fault activity rate have a good response relationship.