贵州凤冈沙坪铀矿床方解石原位U-Pb年代学、黄铁矿微量元素与硫同位素特征及其地质意义  

The Characteristics and Geological Significance of Calcite in-situ U-Pb Chronology,Pyrite Trace Elements and Sulfur Isotopes in the Shaping Uranium Deposit,Fenggang,Guizhou Province

作　　者：刘开坤 金中国 彭松 范云飞 卢平 LIU Kaikun;JIN Zhongguo;PENG Song;FAN Yunfei;LU Ping(Nuclear Resources Geological Survey,Non-ferrous Metals and Nuclear Industry Geological Exploration Bureau of Guizhou,Guiyang 550005,China;Non-ferrous Metals and Nuclear Industry Geological Exploration Bureau of Guizhou,Guiyang 550005,China)

机构地区：[1]贵州省有色金属和核工业地质勘查局核资源地质调查院,贵州贵阳550005 [2]贵州省有色金属和核工业地质勘查局,贵州贵阳550005

出　　处：《东华理工大学学报(自然科学版)》2024年第6期501-511,共11页Journal of East China University of Technology(Natural Science)

基　　金：贵州省地质勘查基金项目(MCHC-ZG20212206-2)。

摘　　要：为厘定沙坪铀矿床成矿年龄及物质来源,利用激光剥蚀电感耦合等离子体质谱仪(LA-ICP-MS),对该矿床开展方解石原位U-Pb测年、黄铁矿原位微量元素和硫同位素微区分析。结果表明,该矿床的成矿早期和成矿晚期都有方解石和黄铁矿形成。成矿早期方解石(Cal1)U-Pb年龄为(74.1±1.4) Ma,成矿晚期方解石(Cal2)U-Pb年龄为(22.1±0.8) Ma。成矿早期黄铁矿(Py_(Ⅰ))的Co、Se、Mo、Pb等元素含量较高,成矿晚期黄铁矿(Py_Ⅱ)的Ni、As、Sb、Tl等元素含量较高。Py_(Ⅰ)的δ^(34)S值为-3.66‰~+4.77‰(平均为-0.42‰),Py_Ⅱ的δ^(34)S值为-9.13‰~-7.47‰(平均为-8.49‰)。黄铁矿形成于中-低温环境,硫主要来源于深部沉积地层和变质基底,由深部成矿流体携带至成矿部位经热化学还原作用形成黄铁矿。在燕山晚期-喜山期造山运动背景下,深部流体向上运移并萃取寒武系黑色岩系中的铀,在成矿有利部位经烃类流体热解分异成矿,沙坪铀矿床属于受深部有机流体-构造复合控制型铀矿。To determine the mineralization age and material source of the Shaping uranium deposit,laser ablation inductively coupled plasma mass spectrometer(LA-ICP-MS)was used to conduct U-Pb dating of calcite,in-situ micro area analysis of trace elements and sulfur isotopes in pyrite.The results show that calcite and pyrite were formed in both the early and late mineralization stages of this deposit.The U-Pb dating of early mineralization calcite(Cal1)is(74.1±1.4)Ma,and late calcite(Cal2)is(22.1±0.8)Ma.The contents of elements such as Co,Se,Mo,Pb in the early mineralization of pyrite(Py_(Ⅰ)),and Ni,As,Sb,Tl in late stage mineralization of pyrite(PyⅡ)are relatively high.Theδ^(34) S values are from-3.66‰to+4.77‰(the average value is-0.42‰)in Py_(Ⅰ),and from-9.13‰to-7.47‰(the average value is-8.49‰)in PyⅡ.The studies show that pyrite was formed in the medium-low temperature mineralization stage.Sulfur mainly was originated from deep sedimentary strata and metamorphic basement,carried to the metallogenic site by deep ore-forming fluids,and formed pyrite through thermochemical sulfate reduction.Under the background of the late Yanshan-Himalayan orogenic movement,the deep fluids transported upward and extracted the uranium in the Cambrian black rocks,which was mineralized by hydrocarbon fluid pyrolysis and differentiation in the ore-forming favorable parts.The Shaping uranium deposit was controlled by deep organic fluid and composite structure.

关 键 词：方解石 原位U-Pb法 年代学 黄铁矿 微量元素 硫同位素 沙坪铀矿床 

分 类 号：P611.1[天文地球—矿床学]