Recovery Of Original Rocks And Geochemical Characteristics Of Metamorphic Rocks In The Kanas Group Of Altai,Xinjiang

Altay orogenic belt is an important part of the central Asian orogenic belt,the presence of Precambrian continental crust basement and orogenic belt in the era of deep metamorphic rocks has been controversial.In this paper,Kanas group of schist as the research object of this article,the SiO2 contents range from 58.76% to 60.33% and ? < 1,belong to the calc-alkaline series.Major element fall into the K-A relationship argillaceous siltstone,explain the schist is pararock,the metamorphic rocks are mainly argillaceous sedimentary rocks,the individual is sandy sedimentary rocks.The schist are enrichment in LILE(Rb,Th,Ce,Zr,Hf),obvious negative anomaly in HFSE(Ta,Nb,P,Ti)and Eu.reflect the characteristics arc magma activity.Hold Kanas group of schist located in the magmatic type passive margin.The metamorphic rocks in the La,Ce,?REE,LREE/HREE,sigma delta Eu values indicate that the protolith formed in continental arc setting.LA-ICP-MS zircon U-Pb dating result indicate that the zircon is magmatic zircon.206Pb/238 U age concentrated in 500~530 Ma.One of the 31 points consisting of harmonic diagram is(500�3Ma)Ma,to determine strata minimum age.Another group of age(931.2�9.2Ma)have Precambrian ancient zircon age information.Indirect proof Altay orogenic belt have Precambrian continental earthcrust basement.Basic determine after the kanas group formed in the Cambrian point of view.Above geochemical characteristics suggest that the Kanas group metamorphic rocks are likely to deposit on the active continental margin of continental island arc environment.It wasspeculated that Kanas group sedimentary and metamorphism occurred between 550�18ma to 430Ma;In combination with predecessors' point of view and the contact relation between the strata,come to the conclusion,kanas group is early Paleozoic strata.