Tectonic Evolution Of The Chaoyanggou Tectonic Mélange Belt In The Yueyasha Area,Eastern Kunlun Mountains,Xinjiang

The Chaoyanggou tectonic mélange belt is located between the Central Kunlun Massif and the Southern Kunlun Accretionary Complex.This tectonic mélange belt had been closed during the Caledonian,and was superimposed and transformed by the Hercynian and Indosinian tectonism.This paper studies on the formation,development,evolution and dynamic mechanism of the tectonic mélange belt by the digital geological mapping,structural geology and petrology and obtains three new ideas as follows:1.The matrix of the Chaoyanggou tectonic mélange belt is composed of the quartz schist and phyllite from Dabangou Group.The carbonatite and the mafic-ultramafic rocks form the blocks of the tectonic mélange and they were unevenly distributed in the the matrix by different size.2.The structural units,structural deformations and tectonic evolution of the Chaoyanggou tectonic mélange belt have been discussed.3.The Chaoyanggou tectonic mélange belt has a width of 7-11 km from the south to north.A number of ductile shear zones and major faults are distributed in the tectonic mélange belt.They strike 320°,most of them dip to NE and minority dip to SW with angles of 55°-85°.The Central Kunlun fault was formed in the intense NE-SW trending extensional stress during the Jinning Movement Period.The break up of the archicontinent resulted in that the northern margin of the Qaidam Massif happened fault depression and formed the rift belt.Accordingly,the geological bodies with different ages experienced the tectonic chaotic process,metamorphism and deformation.Because of the tectonic chaotic process,the rock series displays characteristics of non Smith sequence with disorder in long distance and partial order in short distance.The strong deformable metabasites(degraded to green schists or serpentines),mylonitic quartz schists,carbonaceous phyllites and flake limestones form the matrix of the tectonic mélange belt,while the small lentiform gabbros and serpentines compose the block of the tectonic mélange belt.