Geochronological,Geochemical and Petrogenesis of Bieluagaxi Granodioritic Pluton in Western Junggar
Yang Gang
Xiao Long
Wang Guocan
Gao Rui
He Xinxing
Zhang Lei
Zhou Pei
Abstract：For a better understanding of the petrogenesis and tectonic environment of the acidic intrusive rocks in Western Jung-gar,a study is carried out on Bieluagaxi granodioritic pluton located in the Central part of West Junggar.Its petrogenesis,mag-ma source,tectonics setting based on petrography,zircon LA-ICP-MS U-Pb ages,whole-rock major and trace elements,and Sr-Nd isotopic compositions are discussed in detail.LA-ICP-MS U-Pb zircon data of the granodiorite give weighted ages of 318.7±3.3 Ma.Bieluagaxi granodiorite is calc-alkaline suite with high MgO(Mg# =49 - 59),Ni and Cr contents.Bieluagaxi granodiorite is strongly enriched in large ion lithophile elements (LILEs,e.g.K,Rb,Sr and Ba),but it displays depletion of high field strength elements (HFSEs,e.g.Nb,Ta and Ti).In terms of Sr-Nd isotopic compositions,granodiorite has low ini-tial 87 Sr/86 Sr ratios (0.704 297 -0.704 399)and high positiveεNd (t )(5.8 - 6.5 ).Therefore,we suggest that the early Late Carboniferous Bieluagaxi granodioritic pluton has been generated in a subduction setting,the mantle wedge began to partially melt due to the upward fluid from the dehydration of subducting oceanic slab,resulting in the asthenospheric mafic magma un-derplating the lower crust.Then,the lower juvenile basaltic crust derived from the depleted mantle underwent partial melting to generate the I type granites of the Bieluagaxi granodioritic pluton.
Keywords：Bieluagaxi granodioritic plutongeochronologygeochemistrySr-Nd isotopewestern Junggarstratigraphy
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：14( 810-823 )