Mesozoic Magmatism And The Regional Tectonic Evolution In Guliguta Balinyou.Qi

When Great Xing’an Range is into the Mesozoic (Late Jurassic-Early Cretaceous),it experienced a large-scale tectonic-magmatic activity, Mesozoic intrusive rocks andvolcanic rocks form the main body of the Great Xing’an Range. In southern that, allkinds of faults are extremely developed, which provide good migration pathways for themagma emplacement and volcanic eruptions. the age and lithologic features ofMagmatic rocks are direct reflection of the entire magmatic events and theirgeodynamic background. Therefore, we present new zircon U—Pb age date of granitesusing laser ablation ICP-Ms technique and we did a experiment about the whole rock，sgeochemical analysis of the two types of granite. On this basis, we carried out the studyon petrogenesis,magmatic evolution and diagenetic tectonic dynamics, and theunderstanding:1、Coulee，s granitic rocks, are formed by two periods of diagenesis, the GL01formed in the Late Jurassic (143Ma), the GL02formed in the Early Cretaceous (136Ma).Both were output by small rock mass and intruded into the sedimentary strata of theUpper Permian Linxi group, And with the Upper Jurassic Mani Group，s volcanic rocksconstitute the volcanic－intrusive rocks，portfolio. Volcanic and intrusive rocks areclosely accompanied in space, but Inferred them to form a shorter interval time.2、After the analysis of geochemical elements,both of the granites belong to high-Kcalc-alkaline series, The difference is that the GL01is metaluminous, while the GL02isperaluminous. Comprehensive trace element and REE analysis, the former may be in asqueezed environment,which is formed by the crust-mantle，scontamination and upintrusion, the GL02is formed in the stretching mechanism, by melting of crustalmaterial.3、the causes of the GL01，s form is significantly different with the same periodgranits in surrounding，which is formed in the extrusion environment,but most of thesame period of granites are formed in extensional setting. Such as the Huanggang，smoyite, its Rb-Sr age is142.05Ma. in the process of information，s collection, I alsofound between140Ma-145Ma,the granite，s information is little. The southern GreatXing’an Range，s granite are mostly concentrated in the early or middle Jurassic in extensional tectonic setting after the collision of middle block and North China, or afterthe Okhotsk closed in the Early Cretaceous in extensional environment of plate.4、The tectonic power of GL01has nothing to do with the crust-mantle interactionin the closing process of the Okhotsk. Through the geochemical data，s analysis, it doesnot have the granites within the board,infer formation of the rocks is relate to thelarge-scale sinistral shearing which is caused by that Asian plate was northwardmovement. This shearing within a very short time changed from the compressive stressinto Extension,which is the reason to GL02, its formation may be realate to thestrike-slip in tectonic transited period.On the other side,the reason is that The Pacificplate，s low-angle oblique subduction and the lithospheric stretching in the late Jurassic.