Zircon Geochronology and Geochemical Characteristics of the Permian Granitic Complex at Yiwu,
详细信息
- 责任者：Wang Chuansheng (Eastern China Geoexploration & Development Bureau for Non-Ferrous Metals ; Jiangsu Province ; Nanjing 210007 ; China) ; Zhang Zunzhong
- 刊名：Acta Petrologica Sinica
- 出版年：2010
- 卷期：26(4)
- 关键词：二长花岗岩 ; monzogranite ; 碱长花岗岩 ; alkali feldspar granite ; 铀—铅计时 ; U-Pb dating ; 天山 ; Tianshan Mountains
- 页码：p.1045-1058
- 图表：illus., 6 tables, 45 refs.
- 分类号：0801
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
摘要
The 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±1.4 Ma and 284.0±1.1 Ma 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 (tDM) are calculated to be 693 Ma and 763 Ma for the monzogranite and alkali-feldspar granite, respectively. Both rock types are higher in εNd（t）(+4.53 and +4.64, respectively) and lower in(87Sr/86Sr)i (0.703 858 and 0.703 855, 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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