北京平谷马坊Zk09钻孔新生代地层格架及其地质意义

本文基于北京平谷马坊地区Zk09钻孔新生代地层岩性岩相分析和沉积物古地磁等测试,建立了北京平原泃河水系中下游冲洪积区完整新生代地层格架。其中,0m～180m为中更新世-全新世陆相辫状河和曲流河沉积,180m～240.5m为中新世-上新世残坡积、湖积和三角洲前缘沉积。Zk09钻孔新生代不连续地层揭示了北京平原区两次重要的抬升构造事件：第一期构造事件发生于中新世,而不是前人研究认定的早更新世或上新世末,其最终结束了大渤海湾盆地古近纪盆-岭构造系统演化；第二次构造事件发生于中更新世早期,其可能是目前以走滑运动为主的最新构造变动形式起始时间。

Cenozoic Stratigraphic Framework of Zk09 Borehole and Its Geological Significance in Pinggu, Beijing

Combining the results of the lithologic facies analysis and tests, including paleomagnetic, carbon-14 and luminescence, from the Zk09 borehole in the Mafang area of Beijing, Cenozoic stratigraphic framework of the Juhe water-system in the Beijing sub-plain was established. The stratum of the 0-180 meter was formed from the Holocene to the Middle Pleistocene, and was product of the braided-meandering river sedimentary environment. The stratum of the 180-240.5 meter was formed from the Pliocene to the Miocene,and was product of the delta, lacustrine and elluvial-deluvial sedimentary environment. Cenozoic discontinuous stratigraphic of the Zk09 borehole reveals two important uplift tectonic events in the Beijing sub-plain. The first tectonic event occurred in the Miocene, rather than the early-Pleistocene or the Pliocene, and the result is different from the results of previous studies. The first tectonic event may have recorded the process that driven the extension ceased in the Bohai Bay Basin. The second tectonic event occurred in the early Middle Pleistocene, which may be the starting time of the latest tectonic variation form dominated by the strike-slipping movement.