The Preliminary Study Of Granitoids In Malan,Heshuo Country,Sinkiang,China

The South Tianshan orogenic belt is located between thethe tarim plate and kazakhstanplate，is a typical late Paleozoic orogenic belt.South Tianshan is a late Paleozoic collisionzone which was developed from a broad ocean basin between the Tarim micro-plate andKazakhstan micro-plate.In this context，a large volume of granitoid plutons formed in theSouth Tianshan orogenic belt during Late Carboniferous to Early Permian.Granite has manyclassification schemes，geological scholars compare recognition " I，S，M，A，" classificationscheme.And according to the basic，aluminum，and tectonic environment，such as a varietyof classification schemes.Based on predecessors’ researches and detailed field investigations，this paper mergers and partition granite bodies， studies the mineralogy， perology，geochemistry and Zircon U-Pb chronology of yigaierqiaiken granitic Plutons and discussesthe cause of the granites，Source area characteristics and Tectonic environments.summarizesthe following conclusions are drawn：①Granodiorite and monzonitic granite of yigaierqiaikengranitic Plutons are cognate magma evolution series products of high potassium calciumalkaline aluminium magnesium characteristics of granite，and all belong to the I type granite，source area in general is given priority to with igneous rocks.②The yigaierqiaiken graniticPlutons should be early mantle-derived magma intrusion into the lower crust rocks formedwith ancient crustal material under the late thermal events and mixed partial melting magmaintrusion.③The crystallization age of the monzonitic granite in the yigaierqiaiken graniticPlutons was （291±2）Ma and it belongs to the early Permian.The crystallization age ofmoyite was （277±3）Ma and it belongs to the early Permian.④The yigaierqiaiken graniticPlutons was formed in the tectonic environment of collision-after the collision.Based on theanalysis above，the time of south tianshan study area in the post-collision tectonic setting isabout300Ma~285Ma.This illustrates that the late Paleozoic South Tianshan Ocean closed atthe early Carboniferous and the Tarim plate and Kazakhstan plate collided into orogenesis.Atthe end of the carboniferous（the300Ma or so），the collisional orogeny completed，and thesouth tianshan collisional orogenic belt transformed into post-collision tectonic setting.