Geochronology,Geochemistry and Zircon Lu-Hf Study of Granites in Western Section of Xiemisitai Area,Western Junggar
Yang Gang
Xiao Long
Wang Guocan
Gao Rui
He Xinxing
Yan Shengwu
Yang Wei
Yan Wenbo
Zhou Pei
Abstract：LA-ICP-MS U-Pb zircon age,geochemistry and Lu-Hf isotopic data for Xiemisitai and Halegaitexi granitic plutons in the western Junggar are presented in this paper,aiming to determine their forming ages,source regions and tectonic settings. LA-ICP-MS zircon yields 427.6±2.3 Ma for Xiemisitai alkali feldspar granites and 428.6±2.5 Ma for Halegaitexi alkali feld-spar granites,respectively.Xiemisitai alkali feldspar granites are characterized as the Ⅰ-type granite,while Halegaitexi alkali feldspar granites have geochemical characteristics similar to the A-type granite.Zircon Lu-Hf isotopic compositions indicate thatεHf (t)=12.4-14.5,two-stage model ages (tDM2 )range from 497 to 603 Ma.The petrogenesis of Ⅰ-type and A-type granites were results of different evolutive phases of the same source magma in the compressible to extendable period of the post-collisional phase,which may be derived as follows.The southward subductional Irtysh-Zaysan Oceanic crust subductioned to the asthenospheric mantle which is the bottom of Boshchekul-Chingiz volcanic arc,resulted in the asthenospheric mafic mag-ma underplating the lower crust.Then,the lower juvenile basaltic crust derived from the depleted mantle underwent different degrees of partial melting and fractional crystallization to a certain extent to generate the Ⅰ-type and A2-type granites.
Keywords：LA-ICP-MS zircon U-Pb agewestern section of XiemisitaiHf isotopeA-type granitegeochemistry
Publication Date：2015-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：15( 548-562 )