| The paleo-planation surface of the mountain is an important theoretical problem of geomorphology,which has important research value in terms of landform evolution,tectonic activity and plateau uplift rate.The paleo-planation surfaces of Siming Mountain in eastern Zhejiang were discovered in 2006 and were considered to be the most extensive high-elevation plains in the eastern coastal areas of China.It was another discovery in the eastern coastal areas of China after the karst planation surface of the Liaodong Peninsula,the high-level plane in Fujian,the planation surface of the Northern Guangdong and the planation surface of the North China.The discovery of the region's rich landscape resources had added new connotations,which had aroused the attention of academia and local governments.According to the local stratigraphic data,it could be seen that the paleo-planation surface in the study area was probably formed from the Late Cretaceous to the Miocene.During this long period of geological stability,the top of the ancient plains formed the ancient weathering crusts with different thicknesses,which provided a relatively reliable basis for determining the environmental characteristics of the paleo-planation surface formation period.The study of the paleo-planation surface of Siming Mountain was mainly based on the characteristics and causes of the landscape.At present,the research on the scope of the paleo-planation surface area and the environmental characteristics of the paleo-planation surface formation have not been reported.Therefore,for the first time,this study has made a preliminary discussion on the morphological characteristics and paleoenvironment of the paleo-planation surface.The paper is based on the synthesis of DEM data and ArcGIS analysis,field verification sampling and experimental analysis,and discusses the geomorphological features of the paleo-planation surface of Siming Mountain and the characteristics of the ancient weathering crust(paleosol)Paleoclimatic;initially delineated the area of the paleo-planation surface,to explore the paleo-planation surface distribution,terrain,slope and other morphological characteristics.The following conclusions were obtain through the study:(1)The ideal slope of the paleo-planation surface was 9 °,14 ° and 14 °,respectively,and the corresponding elevation was mainly distributed between 490-577m,570-782m and 624-867m in the north,middle and south of the study area.From the distribution of the paleo-planation surface,the north was mainly distributed in the Shangwang and Dayang;the central part was mainly distributed in the Dalan and Luocheng around;the south was mainly distributed in the sides of the Siming,there are eight parts.The paleo-planation surface were basically symmetrical with the main watersheds and were discontinuously distributed.Some areas were relatively well preserved and the total area was about 199.5km~2.(2)The slope of the apaleo-planation surface had good agreement with the undulating degree of the terrain.The slope type was mainly gentle slope and low steep slope,and the terrain fluctuation type was dominated by plain and platform.It showed that the paleo-planation surface in the study area fluctuates on the microscopic scale Relatively small,some local ups and downs.By analyzing the vertical and horizontal profiles of the study area,it was found that the elevation distribution of the apaleo-planation surface decreases from south to north and the slope was between 1.2 ° and 1.7 °.According to the fracture structure data of the study area,the fracturing was controlled by the regional structure,and the NE-SW tectonic control was stronger than the near EW to the fault structure,and the fault activity in the south was stronger than that in the north.(3)The clay mineral data of the Nanlan section(NL)and the Baiyuping section(BY)were the characteristics of chemical weathering,and the degree of illite was poor.The climate was warm and humid.In addition,the leaching of Ca,Na,K,Mg elements in the two sections was most significant,accompanied by slight leaching of Si elements,and also indicates strong chemical weathering.The results showed that the CIA value,A-CN-K,element ratio and the clay mineral assemblage indicated a warm and humid paleoclimate environment. |
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