The Geochronology And Petrogenesis Of Volcanic Rocks In Manitu Formation From The Southern Of Wulanhaote Region

Manitu Formation in the area of Wulanhaote region，Great Xing’an Range，isdominated by a set of neutral volcano rock and a small amount of neutral volcanic clastic.lithology is mainly purple-purple andesite, andesitic lava, pyroclastic tuff rock and asmall sink. Petrography of basaltic andesites, andesite, trachyte, dacitic tuff breccia, tuff,etc. trachyandesite. Comebined with field investigation and zircon U-Pb isotopic datingresults on Manitu Formation of Hao rao Mountain of Great Hinggan Range during LateJurassic period，this paper systematically studied the combination of lithology and thetiming evidence，and discussed the structural properties of its formation.This paper draws the following understanding: Ulanhot area Mani spit groupdistributed more large distribution area, in the study area were planar distribution.Wulanhaote region Mani spit facies volcanic rocks are mainly effusive phase, a smallamount of the outbreak fallout facies, volcanic action-oriented approach to the overflow,which burst with intermittent small-scale eruption way. Wulanhaote region Mani spitvolcanic rocks LA-ICP-MS zircon U-Pb dating results for142.2±2.4Ma, formed in theearly Early Cretaceous. Geochemistry show that volcanic rocks spit Wulanhaote regionMani is a high-K calc-alkaline series of acid rock composition, geochemistry lithology isandesite, matte andesite, dacite, matte rhyolite and dacite rock. Higher abundance of rareearth elements, LREE fractionation obvious weak positive Eu anomaly, enriched in LILE,depleted in high field strength elements, has a shell source magma characteristics.The volcanic rocks of Manitu Formation in the Wulanhaote region is formed inMongolia-Okhotsk Ocean closing stages of the collision orogenic tectonic setting, which may be thickened crust under different mineral phases of partial melting of residualproduct.