Paleoclimate And Paleovegetation Of Debris Flow Happened In NiDePing Mesa JiangJia Channel In DongChuan Of Yunnan

It is not common in China to study paleoclimate and paleovegetation characteristic through mud flow deposit. However, good carriers of reconstructing palaeoenvironment and containing global changing information are Loess, Deep Sea Deposit and Polar Ice-Core. Although environmental information recorded in ancient mud flow is not as particular as polar ice-core, deep sea deposit and loess, and continuity is not high enough. However, the environmental information that recorded in ancient mud flow can represent abundant rainfall in specific area and specific time, also represent special environment that tectonic movement intensity in local area and terrain divide large.This article selected sedimentary section as research object in ancient mud flow mesa in NiDePing mesa JiangJia channel in Yunnan province, analyzing samples in the section, and four branch trenches sporopollen samples of JiangJia channel-DaAoZi channel, ChaQing channel, DuoZhao channel and MenQian channel. Comparing sporopollen combination between source region and accumulation area in bottom of trench, finding whether accumulation area sporopollen samples has relation with source region sporopollen samples, using the result to reconstruct the paleoclimate and paleovegetation characteristic that happened in the source region of NiDePing mesa.The conclusion:(1) The sporopollen combination in the source region can reflect the accumulation area of DongChuan JiangJia channel's four branch trenches-DaAoZi channel, ChaQing channel, DuoZhao channel and MenQian channel, and also the sporopollen combination in source region can reflect the trees around the samples. NiDePing deposit mesa is near these branch trenches, so the sporopollen combination of NiDePing mesa can reflect its resource region's paleoclimate and paleovegetation characteristic.(2) The sporopollen spectrum reveals pollen beltâ… 1-4,â…¡,â…¢1-3,â…£andâ…¤1-2,which altitude are from 1222.4m to 1244.9m,1247.6m,from 1248.5m to 1263.8m,from 1271.0m to 1274.6m,from 1285.4m to 1301.6m.The vegetation types changed from broadleaved deciduous forest, theropencedrymion, broadleaved deciduous forest-theropencedrymion, sylvosteppe to broadleaved deciduous forest.(3)From the vegetation types above, the paleoclimate in source region of NiDePing mesa had gone through humid temperate climate, relatively dry and cold, humid temperate climate-relatively dry and cold, humid temperate climate. The period of relatively dry and cold can provide material basis that are necessary for mud flow, and the period of humid temperate can provide abundant rainfall for mud flow. The favourable terrain that formed by tectonic uplift and torrential rain because of monsoon climate makes the resource region of NiDePing mesa had gone an active period.