The Characteristics Of The Fragmental Texture And Clastic Constituents Of The Sand Dune By The Vicinity Of Tumenjiang River

Tumenjian River originates from the easterly mountain slope of the highestpeak in Changbaishan mountain range. The dunes in the Estuary of TumenjiangRiver in China lie to the area between the Jiushaping and Fangchuan in the left bankof Tumenjiang River. The distance is about 15km between the dunes and the coast. Itranges from China to D.P.R. Korea and Russia. The objective of this research is todescribe the characteristics of the fragmental texture and clastic constituents of thesand dune by the vicinity of Tumenjiang River, discusses the geologic origin of thesand dune. Furthermore illustrates the response of the sedimentary sequences forglobal paleoclimate. Acquisition of such objective, the techniques applied in this study include GPSfixed-pointed, digital image pick-up, measuring the profile section,thermoluminescence dating, thin-section observing, Scanning Electro Microscope(SEM) observation, energy spectrum analysis, cathode luminescence image, grainsize analysis, composition analysis, the geochemical analysis of the macroelementand microelement in paleosols and etc. During this research, we invited the coastexperts for the field examine and intercommunicate the understanding about thesand dune in Tumenjiang River. By the GPS fixed-pointed, digital image pick-up and measuring the profilesection, the macroscopic distribution and morphological character were identified inthis area, the development period of the sand dune were divided and themorphological development were disclosured. The range orientation of theJiushaping sanddune field and the spread direction of the Tumenjiang River are highangle oblique crossing. These dunes' scale are little and its' distributing arecontrolled by winter northwest wind. The distributing of the Fangchuan sand dunefield are linear along the Tumenjiang River riverside, These dunes' scale are big andits' distributing are controlled by winter North-West wind and southern wind andeast-south wind in summer. The sand dunes' development period are divided four stages, the first andsecond stage spread in Fangchuan sand dune field, most of them are stabilized dune,the third and fourth stage appear in the Jiushaping sand dune field and Fangchuansand dune field, most of them are semifixed sand dune and movable sand dune. Thesand dunes' shape in this area are various, most of the Jiushaping sand dune arelunate, but the shape of the sand dunes in Fangchuan sand dune field are manifold,including the lunate cross sand dune, the lunate sand ridge, pyramiding sand dunesand the dome sand dune which were covered by plants. The development periods ofIV图们江口附近沙丘沙的结构与碎屑成分特征the lunate and pyramiding sand dunes are specific. By thin-section observing, Scanning Electro Microscope (SEM) observationand grain size analysis and etc, the microscopic characters of the sand dune werestudied and the sedimentary environment of the dunes was identified. The degree ofroundness of grain edges is subangular to subrounded. The mechanical characteristicmarkings include conchoidal fractures, step-like fractures, mechanical V marks,dish-shaped concavities and straight or curved grooves and scratches etc. Thechemical characteristic markings include solution holes, recrytalization, silicacoating, silica deposits, surface solution features etc. Through the statistic and thequantitative analysis, it is known the The degree of roundness of grain edges is lowindicating the sediment may be the deposited closely. The conchoidal fractures,step-like fractures, mechanical V marks and the straight or curved grooves can beseen in the same grain, these preserved marking show the marks of fluvial sands.The recrytalization of the quartz may be the result of the diagenesis and thedish-shaped concavities on the surface of the roundness grains may be eolian. Thedegree of the selection accumulation and psephicity of the Fangchuan sand dunefield is better than the Jiushap...