Zircon geochronology and geochemical characteristics of the Permian granitic complex at Yiwu,eastern Tianshan:Their tectonic significance
2010; Science Press; Linguagem: Inglês
ISSN
2095-8927
Autores Tópico(s)Geochemistry and Geologic Mapping
ResumoThe Yiwu granitic complex is mainly composed of a monzogranite and an alkali-feldspar granite phases.Zircon LA-ICPMS U-Pb dating gave ages of 284.6±1.4Ma and 284.0±1.1Ma for the monzogranite and alkali-feldspar granite,respectively, indicating their Early-Permian emplacement in accompany with post-collisional compression-extension transition.Petrological, geochemical and isotopic studies suggest that these rocks were evolution products from the same magma.In comparison with the monzogranite,the alkali-feldspar granite is higher in Si,alkai,DI and Rb/Sr,and richer in Th,U,Nb and Ta,but lower in Al,Sr, P,Ti,Sm,Nb/Ta and Zr/Hf.A continuous differentiation trend is exhibited from monzogranite to alkali-feldspar granite.Model ages (t_(DM)) are calculated to be 693Ma and 763Ma for the monzogranite and alkali-feldspar granite,respectively.Both rock types are higher ine_(Nd(t))(+4.53 and +4.64,respectively) and lower in(~(87)Sr/~(86)Sr)_i(0.703858 and 0.703855,respectively).It is suggested that the magma for the Yiwu granitic complex was produced by partial melting of a Neoproterozoic depleted-mantle-sourced juvenile mafic crust,and the alkali-feldspar granite represents the residue of the monzogranite parental magma after fractionation of plagioclase, apatite,Ti-Fe-oxides,sphene,monazite,allanite,zircon etc.
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