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Hebei Normal University (2021)

Study on the Grain Size Characteristics of Tamarix Cones Sedimentary Laminae in the Northern Area of Lop Nur and the Changes of Wind-sand Environment and Its Source

熊祯祯

Titre : Study on the Grain Size Characteristics of Tamarix Cones Sedimentary Laminae in the Northern Area of Lop Nur and the Changes of Wind-sand Environment and Its Source

Auteur : 熊祯祯

Grade : Master 2021

Université : Hebei Normal University

Résumé partiel
Grain size characteristics are one of the basic indicators of sediment research,which carry the initial information and change information during the deposition process,especially in the desert area under the wind-sand deposition environment,which can accurately and effectively reflect the source of sand in the sediments,Sedimentary dynamics and sedimentary environment.The northern area of Lop Nur is located in the eastern part of the Tarim Basin in Xinjiang,adjacent to the Kumtag Desert in the east,the Kuluktage North Mountain in the north,and the Kuluk Desert widely distributed in the south.Its environmental evolution is the epitome of the environmental evolution of the entire Tarim Basin and surrounding mountains.This area is a typical extreme arid continental climate zone,with climatic characteristics such as scarce precipitation,large evaporation,large temperature difference,and strong wind.Tamarix cones is a biological landform formed under this special climatic and environmental conditions,and it is the product of long-term interaction between Tamarix chinensis and climatic environment.According to the sand material grain size characteristics of the sedimentary laminae of Tamarix cones,the sedimentary environment and the source of the sand materials can be revealed.According to field surveys combined with satellite images,it is found that Hongliujing and the lower reaches of the Kongque River are the main concentrated areas of Tamarix cones in the northern area of Lop Nur.This paper takes the Tamarix cones sedimentary layer in the northern area of Lop Nur as the main research object.Through field investigation and systematic sampling,using the method of aeolian sand geomorphology,the sedimentary layer of the Tamarix cones at two sampling points is firstly dated,and then two samples are taken.Tamarix cones point-deposited layer of grain size and characteristics of the different regions of sand sediment material comprehensive analysis,then analyze environmental changes in northern sand Lop Nur region,and to study its material source of sand,the results showed that :(1)Using the three dating methods of 210 Pb,137Cs and 14 C,the chronological sequence of the sedimentary laminae of Hongliushabao at two sampling points in the northern Lop Nur area was initially obtained as 1832~2019 and 1784~2019,respectively.(2)The two sampling points in the northern area of Lop Nur have the same size composition of the sedimentary layers of the Tamarix cones,and the sedimentary environment is the same.The average content of fine sand and coarse powder is the highest,while the average content of clay is very small and does not contain Very coarse grained.In the characteristics of the grain size parameters of the sedimentary layers of Tamarix cones at the two sampling points,the average grain size and the median grain size are between 2.76 and 3.70 Ф,and the sortability is poor,the skewness value is negative,and the kurtosis is sharp.

Mots clés : Tamarix cones ;sedimentary veins ;sand source ;North Lop Nur ;

Présentation (CNKI)

Page publiée le 18 novembre 2021