Zircon U-Pb age,geochemical characteritics of volcanic rocks in the Manitu Formation in Huzhong area,Great Hinggan Mountains and geological significances
Objective:The volcanic rocks of the Manitu Formation were formed in the Late Jurassic-Early Cretaceous in the Great Hinggan Mountains.By petrological,geochemical and isotopic chronological study of the Manitu volcanic rocks in Huzhong area,the origin,formation age and tectonic setting of the rocks are discussed.Methods:Based on 1∶50000 field work,the petrogeochemical test and LA-ICP-MS zircon U-Pb dating were carried out on the volcanic rocks of the Manitu Formation.Results:Systematic LA-ICP-MS zircon U-Pb dating of the medium-acidic volcanic rocks of the Manitu Formation yielded an isotopic age of 154.5±8.6 Ma,indicating a Late Jurassic age of formation.The rocks are enriched in Rb,Ba,Th,La,Ce,Nd and Hf elements,and light rare earth elements;loss Nb,P and Ti elements;belong to the metaluminous-alumina-high potassium-alkalic calcic rock sreies.The intermediate-acid volcanic magma in the Manitu Formation may be derived from the partial melting of the lower crust caused by the addition of subduction plate fluid,and then the separation crystallization occurred.Conclusions:The tectonic setting is an active continental margin formed by the subduction of the paleo-Pacific plate to the Erguna block.
万方数据
维普
