The Sedimentary Characteristics Of Gansu Maxianshan Of Glacial Deposits

The Maxian mountain (3670m) is located in Qilian geosynclinal system and QinlingMountains geosynclinal system, composed of Maxianshan tectonic belt and Xinglong tectonicbelt parts, in the transition part of northwest arid area, Eastern monsoon humid area, insideChina and the Qinghai Tibet plateau region of three natural areas,The climate is typical ofsemi-arid sub humid climate. The Maxianshan whether glaciation remains controversial.Therefore, research on sedimentary characteristics of Maxianshan of glacial deposits hasimportant scientific significance for the determination of Maxianshan glaciation occurred, allhas the vital significance to the restoration of the ancient environment and distinguish thehydrodynamic conditions etc.In this paper, the Maxian mountain as the research area, the process of field geomorphicinvestigation by relative geomorphological method and indoor analysis, conducts the researchto the Maxianshan glaciation period and sedimentological characteristics.Between the OSLdating results of3.4±0.2to13±0.6Ka B P, more precisely the Maxianshan ice into the midHolocene (MIS1,6.4±0.3) Ka B P, and during the last glacial period, late glacial was10.1±0.5Ka,10.3±0.5Ka,12.1±0.6Ka,13±0.6Ka B P two stage.Analysis of the Maxianshan moraine matrix size, and Baima Snow Mountain, the snowcapped mountains, Maya Luoji Mountain, thousands of Hushan, Laojun Mountain, theTaishan, glacial sediment granularity characteristic are compared, the basic conclusion is:between the Maxianshan area glacial sediments mean diameter between0.01559~0.4067mm,average particle diameter of3.69mm, sand and silt sediments and the proportion; particle sizecurve showed a single peak, Shuangfeng and multi peak characteristics; skewness is1.002~2.946; skewness values are greater than0, positively skewed distribution, particleconcentration in the sand and silt; standard deviation (Sd) average3.38mm, sorting is poor;the average kurtosis kurtosis is2, very sharp; mode between10.29~684.2um; the above fivesize parameter values, the Maxian mountain lake and steep forest ditch ridgelike landformsediment as glacial origin.The discovery process were compared in different locations, different time of grain sizeparameters of tills: Although there is a certain correlation between the extent of damagelength and moraines glacier action time, but in the process of moraines survived, grain size parameters also moraines affected from the earth interior force and sediment lithology,climate many of the external forces, the water, the grain size characteristics of sediments isthe result of various factors.Granulometric characteristics of sediments of different categories of present is: morainesare the maximum value at Sd,、Skand Ku, illustrate the moraine, sorting,skewness is extremelypositive bias range, kurtosis is very sharp and loess sediments;Mzmaximum, skewness is thedifference between the other four groups showed negative bias indicates that sediment, loesssediment particles fine grain size parameters of river sediment; values of Mz, Sd, Skand Kuvalues were too small, the separation of river sediments and lacustrine sediments in the best;Mz, Sd, Kuare also showed higher values, the particle size of relatively fine, sorting is poor,kurtosis sharp separation of the ocean; sediments, skewness better positive bias. There aremany factors that affect the sediment grain size parameters, similar factors such as thesedimentary environment, sediment particle composition, its handling hydrodynamicconditions, capacity and other factors, while the causes of different sediments also has ownparticularity.