A river erosion estimate on the Loess Plateau: a case study from Luohe River, a second-order tributary of the Yellow River

Based on fieldwork and terrace ages, which were determined using ¹⁴C, TL and paleosol stratigraphy, a general model was established for the development of the Yellow River terrace system. The ages for the terraces and valley flats of the Yellow River system are T₆—1.67–0.85 Ma BP, T₅—0.85–0.47 Ma BP, T₄—0.47–0.10 Ma BP, T₃—0.10–0.007 Ma BP, T₂—7.0–0.7 ka BP, T₁—0.7–0.3 ka BP, the higher valley flat—0.3–0.15 ka BP and the lower valley flat 0.15–0 ka BP, respectively. Each terrace or valley flat and corresponding paleo-valley represents a river erosion/deposition cycle. Using this model and selected geomorphic parameters of terraces and paleo-valleys from 10 typical cross sections of Luohe River, a tributary of the Yellow River, an attempt is made here to estimate paleo-river erosion since the Pleistocene on the Loess Plateau.     

内蒙古阿拉坦合力苏木汗贝布敦昭奥陶纪裸河组 的重新厘定及其意义

2010—2012年在内蒙古东乌旗阿拉坦合力苏木中蒙边境一带开展1∶5万区调时,根据岩性组合、古生物特征及地层对比等,将汗贝布敦昭地区的奥陶纪铜山组重新厘定为裸河组,并划分出3个岩性段。粒度分析等特征表明,裸河组总体上表现为动荡的滨—浅海沉积环境;化石及区域地层对比、沉积物源分析等特征表明,裸河组的形成时代为晚奥陶世。这些成果为兴安地层区奥陶纪地层的研究和对比提供了有价值的基础资料,对探讨西伯利亚板块南缘活动大陆边缘早古生代地质构造演化具有重要意义。