Discovery and Significance of Malan Loess on the Piedmont Plain in Pinggu District, Beijing

摘要: The platforms on both sides of the Malangou River (a lateral ditch Qingshui that is a tributary Yongding River) where Malan Village in Zhaitang Town Mentougou District Beijing located are place China's typical section Quaternary loess. During investigation eastern suburbs City, authors not only clarified 5 grades terraces Pinggu piedmont plain, but also found clayey silt mixed with small amount alluvial-diluvial gravel layers at height 15–25 m above river level near Fishpond Xinli Nandule Town. Results study grain size document loess mostly silty soil (0.05–0.005 mm), and probability cumulative curves dominated by single-peak, coarse-grained segment I II types, reflecting its depositional environment similar to eolian phase. Identification results heavy minerals from show their contents account for 0.01%–0.11%, averaging 0.04%. There 24 kinds minerals, most which stable clay illite, consistent Loess Plateau. chemical composition data reflect source area relatively arid. six grade classification sporopollen further shows subdivision history alternating warm humid phases this geological period. thermoluminescence dating range 21.0 ka 59.2 ka, convincingly demonstrating indeed consists studies provide new basis overall understanding distribution northeast margin North China Plain change Late Pleistocene.