Research On The Aggradation And Incision Process Of The Main Terraces Of Hutubihe River In The Tugulu Fold Belt Of North Tianshan Mountain

The accumulation and incision process of river have been one of the hotspots of the Geomorpology research.Accurate determination of the time of river accumulation and incision is the key to carry out the above research.The Hutubihe river in the north tianshan mountains originated from the northern foot of the Tianshan mountains is located at the eastern end of the second row of the reverse fault-anticline belt in the foothills.The time zone at the eastern end of the Tugulu fold belt in the hutubi anticline has developed many river terraces.In this paper,the river terrace of this section was selected,and the processes of accretion and incision of this section of river terrace were discussed through satellite image interpretation,high-resolution DEM data analysis,field geological and geomorphic mapping,differential GPS measurement,and detailed photoluminescence dating experiments of the related sediments of the terrace,and the following preliminary understanding was obtained:1.In the west bank of Hutubi River in the Anticline area of Tugulu,a total of T4,T3,T2 and T1 base terraces developed from the old to the new,and the height of tugof-war in the anticline nucleus was 145,55,10 and 5m respectively.T4 and T3 are distributed continuously along the anticline,and fold and fault deformation occur.T3 developed a two-stage pedestal terrace in the south syncline area,and the height of tugof-war was 83 and 60 m respectively.In the north syncline zone,a 1-stage pedestal terrace was developed,and the height of tug-of-war was 30 m.T4,T3 b,T3c and T3 a terraces are developed in the southern syncline,and T3 c and T2 terraces in the northern syncline.2.Wall of hutubi river terrace sediment samples with the weak signal interpretation of light,sun light off completely,slow development of component characteristics,through a series of contrast experiment conditions,determine the specific dating experiment process,using quartz small measurement standard growth curve method(SA-SGC)to determine the age of less than 50000 sediment release light age,age is determined by feldspar heat infrared technology is more than 50000 years of sediment release light age3.According to the photoluminescence dating results of each terrace sample,the formation age of T3 terrace was 33.5ka years ago,the formation time of T2 terrace was estimated to be between 5.7-10 ka,and T1 terrace was about 3.5Ka.The accumulation rate of T3 a and T3 c is about 0.8m/ka and 0.1m/ Ka respectively.The accumulation rate of floodplain facies in the upper T2 terrace in the east coast is 0.2m/ Ka.4.According to the age,the variation of the shear rate and the accumulation rate can be calculated.The shear rates of T3 a and T3 c in the southern syncline of the river are 4-7m/ka and 3m/ Ka respectively,and the accumulation rate of T3 a is 0.8m/ka.In the river anticline region,the cutting rates of T3 c and T3 d were 2.9m/ka and 1.3m/ Ka,the cutting rates of T2 a and T1 were 2.2m/ Ka and 1.6m/ Ka,the cutting rates of T2 terrace in the east bank were 3.8m/ka,and the accumulation rate of T3 c was 0.1m/ka.In the syncline area to the north of the river,the cutting rates of T3 and T2 c were estimated to be 2.5m/ka and 2.9m/ka,respectively.5.Combined with the regional structural analysis,T3 c was affected by the uplift in the anticline at a slower rate than the T3 a accumulated at the same time.Due to the difference in the stacking rate,the uplift rate of the anticline could be calculated to be about 0.7m/ka.Combined with the comparative analysis of regional terraces,the time of T3 subdivision corresponds to the deep sea oxygen isotope(MIS)2 glacial period.The subdivision of T3 terrace should be caused by the climate changing from cold to warm after the upper peak glacial period.These insights lay a foundation for us to further study the active structures and seismogenic faults in the modified area.