The Cenozoic Strata and Depositional Evolution of Weihe Basin: Progresses and Problems

Abstract

On the basis of the previous stratigraphic research,the Cenozoic strata in the Weihe Basin have been recognized and partially revised. The main regional stratigraphic units in the Weihe Basin are compared with the "China Regional Chronostratigraphic( Geo-chronologic) Scale",including the Honghe Formation,the Bauluyuan Formation,and the Lengshuigou Formation,the Koujiacun Formation,the Bahe Formation,the Lantian Formation,the Sanmen Formation and the Quaternary loess-paleosol. We found that the conglomerate at the bottom of Lantian Formation should be thought as the upper part of the Bahe Formation. The Sanmen Formation is defined more clearly that it has no vertical relationship with the Lantian Formation. These two formations are the contemporaneous heterotopic facies within the same deposition period,but over different environments,and they have never been found in one section in the Weihe Basin. The "Zhangjiapo Formation"and the "Youhe Formation"were wrongly founded and placed in time before,they should be concealed and belong to the"Sanmen Formation". The tectonic rifting and sedimentary evolution of the Weihe Basin has been analyzed and reviewed,and the Eocene and late Miocene are found as the two most important developmental stages of the Weihe Basin during the Cenozoic era.The Weihe basin is synergistic and related to the uplifting of the Qinling Mountains and the evolution of the Ordos Plateau in time and motivation.