Stratiform Geomorphology' Development And Significance Of Neotectonic Movement In Wangmangling,Lingchuan,Shanxi Province

A serious of stratiform geomorphology,associated with tectonic movement,are distributed in Wangmangling National Geopark on the southern margin of Taihang Mountains.The vertical and regular distribution of these landscapes is in response to the neotectonic movement and inverses the process of tectonic movement of Taihang Mountains,which is great significance to the study of the evolution of Taihang Mountains.By the field investigation of distribution and characteristics of planation surface,river terrace and karst cave in Wangmangling,optical stimulated luminescence(OSL)dating,the conclusions can be reached as follows:(1)By the field investigation of distribution,altitude and characteristics,geochemical characteristics of the weathering crust and DEM profile in Wangmangling,the conclusions can be reached that there are two planation surface in Wangmangling,which are named Taihang planation surface and Tangxian planation surface.Taihang planation surface is at the elevation of 1400-1600m,above which typical weathering crust and various karst landscapes are appeared;Tangxian planation surface is at the elevation of 1100m,above which weathering crust are appeared.The two planation surface were formed in Oligocene and Pliocene respectively.(2)By the field investigation of sequence and sedimentary features,optical stimulated luminescence(OSL)dating,the conclusions can be reached that there are four levels of river terraces in Pingdian River,T4,T3,T2 and T,terraces' heights are 61-96m,35-54m,19-43m and 3-5m,and ages are 97.4kaB.P.,73.9kaB.P.,48.3kaB.P.and 2.3kaB.P.respectively.After investigation the causes of river terraces,T4,T3,T2 terraces should be the results of tectonic uplift,otherwise T1 is climatic terrace.(3)It can be divided into three vertical levels by the field investigation of karst caves'elevation in Wangmangling.Lingqiu Cave,a typical karst cave,was formed in Middle Pleistocene.With the height and age of Lingqiu Cave,river's incision rate is calculated as 0.35-0.65mm/a since Middle Pleistocene;The karst cave,located at"Shimen",and T2 terrace were formed in 48kaB.P.,which should be the result of tectonic uplift;Niubi Cave,Guaikulong and T1 terrace were formed in 2.3kaB.P.,which should be the product of tectonic uplift and climate change.(4)Incision rate can be used as uplift rate,and then we can make a quantitative study on the uplifting process of Taihang Mountains since late Pleistocene.It reveals that the amplitude of uplift of the area is 90m at least after three stages of stable sedimentation and rapid uplift since late Pleistocene(Qp3),the anplitude and the rate of uplift are 26-42m and 1.11-1.79mm/a,11-27m and 0.43-1.05mm/a,16-39m and 0.35-0.85mm/a respectively.