北京平谷马坊ZK09钻孔新生代地层格架及其地质意义

Cenozoic Stratigraphic Framework of ZK09 Borehole and Its Geological Significance in Pinggu,Beijing

基于北京平谷区马坊地区ZK09钻孔新生代地层岩性岩相分析和沉积物古地磁、碳十四、光释光测试,首次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,0~180.0 m为中更新世-全新世陆相辫状河和曲流河沉积,180.0~240.5 m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。

Combining the results of the lithofacies analysis and tests,including paleomagnetic,carbon-14 and luminescence,from the ZK09 borehole in lithofacies the Mafang area of Pingu district,Beijing,the Cenozoic stratigraphic framework of the Juhe River water-system in the Beijing sub-plain was firstly established.Strata of 0~180.0 m were formed from the Holocene to the Middle Pleistocene,reflecting braided-meandering river facies.Strata of 180.0~240.5 m were formed from the Pliocene to the Miocene,being deposits of delta,lacustrine,and elluvial-deluvial facies.The discontinuousness in the Cenozoic stratigraphy of the ZK09 borehole revealed two important uplift events in the Beijing sub-plain.The first event occurred in the Miocene,but previously believed the early-Pleistocene or the Pliocene,marking the end of the tectonic basin-ridge evolution of the Paleogene in the Bohai Bay basin.The second event occurred in the early Middle Pleistocene,which may be the starting of the latest tectonic change dominated by the strike-slipping movement.