| 武夷山中段司前花岗岩体形成时代、地球化学特征及地质意义 |
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| 关键词:Early Cretaceous A-type granite crustal extension Wuyishan the Siqian granitoids zircon U-Pb LA-ICP-MS |
| 基金项目:国家自然科学基金项目(编号: 41502197);中国地质科学院基本科研业务费项目(编号: DZLXJK201601);中国地质调查局项目(编号: DD20179353; DD20160269) |
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| 全文下载次数: 1913 |
| 摘要: |
| Geochronological and Geochemical Constraints on the Siqian Granitoids in Central Wuyishan and Their Geological Implications |
| This paper presents a combined petrologic, geochemical and geochronological study and Lu-Hf isotopic analysis of the Siqian granitoids in central Wuyishan. The granitoids are predominately composed of biotite monzogranite, and igneous zircons therein yielded a consistent weighted mean 206Pb/238U age of (140±1) Ma. Ten samples from the granitoids yielded the data K2O+Na2O=6.67 wt%~8.25 wt%, K2O/Na2O = 1.16~2.41 and A/CNK ratios of 1.01~1.25. They have high REE content of 177.73×10-6~427.88×10-6, Zr+Nb+Y+Ce content of 262.6×10-6~581.5×10-6, FeOt/MgO ratios of 3.06~3.93, and high 10 000×Ga/Al ratios of 2.64~3.28; all these data are consistent with features of aluminous to peraluminous A-type granite. All zircons from the samples show negative εHf(t) values of –18.6 ~ –7.9, recording a predominant contribution of the melting of ancient crustal rocks to the granitoid sources. These results, coupled with regional considerations, led the authors to believe that the granitoids might have been generated by melting of supracrustal material of the Mayuan Group volcanic-sedimentary rocks. The source rocks might have undergone two melting events in the early Paleozoic and Cretaceous, and the heat that induced crustal melting might have been supplied by asthenospheric mantle upwelling. Geodynamically, the Siqian A-type granitoids may represent a product of back-arc extension induced by roll-back of the subducting Paleo-Pacific plate in the early Cretaceous. |
| XIN Yu-jia,LI Jian-hua,DONG Shu-wen,ZHANG Yue-qiao.2018.Geochronological and Geochemical Constraints on the Siqian Granitoids in Central Wuyishan and Their Geological Implications[J].Acta Geoscientica Sinica,39(3):269-281. |
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