摘要
黄梅尖复式岩体不仅是庐枞盆地出露面积最大的A型花岗岩体,也是长江中下游铀成矿带安徽境内最为重要的产铀岩体之一。文章对黄梅尖复式岩体深部赋矿围岩中粒石英正长岩开展了岩相学、岩石地球化学和Sr-Nd同位素研究,分析探讨了岩石成因及其找矿意义。结果表明:中粒石英正长岩SiO2含量为69.30%~71.36%、Na_(2)O+K_(2)O含量为8.45%~10.26,A/CNK为1.31~1.46,显示高硅、高碱、过铝质岩石系列特征;稀土元素含量较高(ΣREE介于226.8×10^(-6)~1174.7×10^(-6)),LREE/HREE介于8.93~18.54,呈轻稀土元素富集的右倾型配分模式,具有明显的负Eu异常;岩石Isr值介于0.70624~0.70814,εNd(t)值介于-5.2~-7.8。综合前人研究认为,区内岩浆源区可能类似于EMI型富集地幔,且岩浆演化方式以部分熔融为主,形成于强烈的伸展构造背景;铀矿化由深到浅可能经历了由高温到中低温的热液成矿过程,成矿流体呈现出由碱性到酸性演化的特点,反映了庐枞盆地正长岩类深部具有较好的铀钍矿找矿潜力;中粒石英正长岩是寻找离子吸附型稀土矿的有利成矿母岩,具有较好的离子吸附型稀土矿找矿潜力。
Huangmeijian complex pluton is the largest A-type granite one exposed in Luzong Basin,and o one of the most important uranium-producing plutons in the middle-lower reach Yangtze River uranium metallogenic belt in Anhui Province.The study of petrography,petrogeochemistry and Sr-Nd isotope of middle-grained quartzite syenite in the deep ore hosting rocks was carried out,the rock genesis and its prospecting significance were analyzed and discussed.The results show that the content of SiO2 in the medium-grained quartz syenite in Huangmeijian complex pluton ranges from 69.30%to71.36%,Na_(2)O+K_(2)O ranges from 9.76%to 10.26%,and A/CNK ranges from 1.31 to 1.46,which shows the characteristics of high silicon,high alkali and peraluminous rocks.The total amount of rare earth elements is high(ΣREE is between 226.3×10^(-6) to 1174.7×10^(-6)),LREE/HREE is between 8.93 to 18.54,and the REE pattern curve is rightleaning with obvious negative Eu anomaly.The Isr values of the rocks range from 0.70624 to 0.70814,and theεNd(t)values range from-7.8 to-5.2.According to the previous studies,the magma source area of the ore-bearing wall rock may be similar to the EMI enriched mantle,and the magma is mainly evolved by partial melting formed in an extensional tectonic background.The regional uranium mineralization experienced a hydrothermal process from high temperature in depth to low temperature in the shallow,the characteristics of ore-forming fluid showed a evolution process from alkaline to acidic,reflecting that the deep part of syenite in Luzong Basin has good prospecting potential for uranium and thorium deposits.The medium-grained quartz syenite is a favorable metallogenic parent rock for finding ion-adsorbed rare earth deposits.
作者
杨彪
陈光旭
陈经龙
史春旺
刘杨
杨毅
YANG Biao;CHEN Guangxu;CHEN Jinglong;SHI Chunwang;LIU Yang;YANG Yi(Anhui Nuclear Exploration Technology Central Institute,Wuhu,Anhui 241000,China)
出处
《铀矿地质》
CAS
CSCD
2024年第6期1132-1147,共16页
Uranium Geology
基金
安徽省地质勘查基金项目(编号:2016-3-2、2021-1-8、2023-2-9)资助。
