高校地质学报2018，Vol.24Issue(2)：172-184,13.DOI:10.16108/j.issn1006-7493.2017076
三江口东岩体岩石成因及产铀潜力分析
Study on Petrogenesis and Uranium Mineralization Potential of Eastern Sanjiangkou Granitic Pluton
摘要
Abstract
The southern Zhuguangshan composite pluton(SZCP)is one of the important uranium resource bases of China.The S-type granites in SZCP have a close relationship with uranium ore deposits, while the I-type granites in SZCP possess no uranium metallogenic potential. The Sanjiangkou granitic pluton in the western part of SZCP has similar lithology to the adjacent Yanshanian Changjiang granite which is a S-type granite and hosts uranium ore deposits. Till present, the Sanjiangkou granite has rarely been studied, its precise chronology is lacked and its genetic type needs to be determined. In this paper, an integrated study including geochronology, petrogeochemistry and Sr-Nd isotopic geochemistry of eastern Sanjiangkou granite and comparison with uranium-bearing Changjiang granite has been conducted.LA-ICP-MS zircon U-Pb dating for the eastern Sanjiangkou granite yields an age of 161.9±2.1 Ma,suggesting its emplacement in the early Yanshanian period.Chemically,the granite has high SiO2contents(73.5％～76.1%)and low FeOT(1.12%～3.25%),MgO(0.07%～0.83%)and CaO(0.64%～1.27%)contents,thus is highly fractionated with high differentiation index(DI)values(86.4～93.6).A/CNK values of the granite vary from 1.00 to 1.35,indicating that it is a peraluminous to strongly peraluminous granite.The granite is depleted in Ba,Sr,Nb,Eu and Ti,but enriched in Rb,Th and U,showing characteristics of a typical low Ba and Sr granite.The rock samples display medium total REE contents(∑REE=119×10-6～268×10-6),and their REE distribution patterns are right-inclined.Isotopic geochemical analysis results reveal variable initial 87Sr/86Sr ratios(0.70789～0.71488), yet low and constant εNd(t) values (-10.8～-9.6) with two stage model ages of 1.73～1.83 Ga. The geochemical and geochronological characteristics of the eastern Sanjiangkou granite are similar to those of the Changjiang granite.Both of them are believed to be S-type granitoids.Combining zircon U-Pb dating and regional tectonic setting,we suggest that the genesis of these granites were likely related to the crustal extension during the early Yanshanian in South China,and they were generated through partial melting of the Mayuan Group para-metamorphic rocks, with possibly minor involvement of mantle materials. Compared with the Changjiang granite, the eastern Sanjiangkou granite is believed to possess prosperous uranium mineralization potential.关键词
三江口东岩体/锆石U-Pb定年/S型花岗岩/铀成矿潜力Key words
eastern Sanjiangkou granite/Zircon U-Pb dating/S-type granite/uranium mineralization potential分类
天文与地球科学引用本文复制引用
兰鸿锋,凌洪飞,陈卫锋,刘建伟,欧阳平宁..三江口东岩体岩石成因及产铀潜力分析[J].高校地质学报,2018,24(2):172-184,13.基金项目
973课题(2012CB416703) （2012CB416703）
中国核工业地质局高校铀矿地质科研项目资助 （）
