The Geological And Geochemical Studies Of Mesozoic Volcanic Rocks In West Ujimqin Banner, Inner Mongolia

West Ujimqin Banner，Inner Mongolia located in the greater Xingan south of the FiveRidges, is a part of Xingmeng orogenic belt which is formed from the collision of the NorthChina plate and Siberia plate. The Mesozoic volcano rock in study area is widelydistributed, mainly for the upper Jurassic manketouebo formation (J3mk), manitu formation(J3mn) and the lower Cretaceous baiyingaolao formation (K1b), NE-NNE trending.Through field geological survey, analysis of indoor thin section analysis and silicate,research area of three groups of volcano rock has the characteristic of "two acid clip",namely the older strata manketouebo formation for acidic volcano rock, rock the rhyoliticvolcano clastic rocks and rhyolite interbedded thin volcano sedimentary rocks, intermediateto latite, latite tuff and other neutral rocks dominated the manitu and the rhyolitic volcanoclastic rocks, a new stratigraphic baiyingaolao clip rhyolite.Take the typical samples of three groups of Mesozoic volcano rock, by silicateanalysis, found that three groups of volcano rock major element showed characteristics ofhigh alkali, Gao Jia, low magnesium, calcium poor, manketouebo formation generally highpotassium calc alkaline series and shoshonite series, manitu potassium shoshonite series,baiyingaolao are of high K calc alkaline series.Show the characteristics of trace elements, the manketouebo and baiyingaolao acidicvolcano rocks have similar characteristics, enrichment of large ion dear stone elements(LILE) Rb, K and high field strength elements (HFSE) Zr, Hf, Y, Th, U, loss of high fieldstrength elements (Nb, Ta, HFSE) has a strong negative Eu anomaly, height loss of Ba, Sr, P,Ti; the manitu volcano rocks are enriched in large ion dear stone elements (LILE) Rb, Ba,K and high field strength elements Zr, Hf, loss of high field strength elements (HFSE) Nb,Ta, Sr, P, Ti height loss. Determination of trace elements of standard curve shows a Nb Taslot obvious, that the genesis is closely related with the continental crust, but also have amantle source components into.Three groups of REE volcano rocks in the study area is divided curve was obviousright inclined REE fractionation, obviously, the enrichment of LREE, hree relative loss. Themanketouebo and baiyingaolao acidic volcano rock, obvious negative europium anomaly,manitu trachyandesite without Eu anomaly.Geochemical analysis indicates that the study area, manitu rough Ann magma with thecrust mantle mixed source characteristics, mainly from the roots and thickening of the crust,mantle component were introduced; the manketouebo and baiyingaolao rhyolitic magmaformed by partial melting of crustal materials to form, the source region the most likely tobe of lower crust.