Coastal Dune In Panjin Formation Process And Its Environmental Response

Coastal dunes widely distributed in China, while sediment can recordenvironment evolution well, therefore they are served as an important complement toreveal change of environment. This article selects coastal dunes in Panjin for object ofstudy, and carry out research work by adopting fieldwork, selecting the typicalprofiles and sampling, experimental analysis indoor, regional comparative andcomprehensive analysis. Grain size characteristics of the coastal sand and theirchronology potentially help us to determine the formation age of the dunes. Combinedtopography, climate and hydrological data and other aspects of dunes we analyze thecause of formation dunes in Panjin. Based on Optically Stimulated Luminescence（OSL）ages and compared eastAsian monsoon change sequence, the last millenniumregional precipitation and temperature changes recorded in Panjin, then we discussControlling factors of dune formation. Through the above analysis, we conclude that:（1）Grain size characteristics show that Coastal dunes in Panjin are composedof medium sand and fine sand, sorting modestly, the grain size frequency distributionof Panjin is unimodal added a fine tail, kurtosis narrow. Compared with the typicalcoastal dunes, sediment in Panjin is partial fine and the fine tail of grain sizefrequency distribution is more obvious, the reason maybe that sediment is Sufferedweathering once deposited. Grain size characteristics of the coastal dunes in Panjin issimilar to other regions, showing a typical coastal aeolian dune features.（2）We can make a conclusion that0.2m above part of aeolian sand dunes,0.2mfollowing section is gray-black sandy clay, through field observation for sention3ofcoastal dunes in Panjin, combined f grain size characteristics. and differencesindicates a change in cross-sectional depositional environment, and to determine thelower boundary of the dune.（3）Based on OSL ages, we determine development of dunes in nearly800years, Controlling factors of dune formation are dry and cold weather conditions,compared east Asian monsoon change sequence, the last millennium regionalprecipitation and temperature changes recorded in Panjin. （4）Favorable conditions for the formation of Coastal dunes: Daling and Liaoherivers carry large amounts of sediment into the sea, and the sediment provides amplematerial sources for formation of dunes, persistent dry spring onshore windssouthwest provides dynamic conditions for formation of dunes, Wide flat terrainconditions in Panjin is favorable to transport beach sediment to shore, and formcoastal dunes.