内蒙古红山子铀钼矿床辉钼矿Re-Os同位素和锆石U-Pb年代学研究及其地质意义  

Zircon U-Pb and Molybdenite Re-Os Dating for Hongshanzi Uranium-Molybdenum Deposit in the Inner Mongolia and Its Geological Significance

作　　者：纪宏伟 牛子良 东前[1] 张闯[1] JI Hongwei;NIU Ziliang;DONG Qian;ZHANG Chuang(Beijing Research Institute of Uranium Geology,Beijing 100129,China;Geological Party No.243,CNNC,Chifeng,Inner Mongolia 024000,China)

机构地区：[1]核工业北京地质研究院,北京100029 [2]核工业二四三大队,内蒙古赤峰024000

出　　处：《铀矿地质》2021年第5期810-822,共13页Uranium Geology

基　　金：核能开发项目“华北陆块北缘红山子地区铀多金属矿综合评价技术研究”(编号:地H037-11);中核集团集中研发项目“二连盆地东部铀矿钻探查证研究”(编号:地LCEQ03-07)联合资助。

摘　　要：红山子铀钼矿床位于华北陆块北缘的沽源-红山子铀多金属成矿带和西拉沐沦钼多金属成矿带上,该矿床内发现有发育在花岗斑岩内的辉钼矿化。通过对辉钼矿进行Re-Os同位素测定,获得模式年龄为(137.2±3.2)Ma和(138.2±2.1)Ma,对围岩花岗斑岩锆石进行SHRIMP U-Pb同位素测定,获得成岩年龄为(133.1±1.2)Ma。两种方法获得的年龄相近,表明成矿和成岩大致同时形成,均属早白垩世。另辉钼矿的Re含量为(186.6~216.8)×10^(-6),表明该钼矿化的成矿物质来自于地幔。通过与西拉沐沦钼多金属成矿带的典型矿床开展综合分析,认为红山子铀钼矿床的发育在花岗斑岩内的钼矿化具有斑岩型钼矿化特征,且应属该成矿带的138 Ma成矿期,该矿化是在白垩纪华北克拉通岩石圈减薄的大地构造背景下,由地幔组分与岩石圈作用形成的岩浆携带地幔含矿流体上侵而形成的钼矿化。Hongshanzi U-Mo deposit is located in composite part of the Guyuan-Hongshanzi uraniumpolymetal metallogenic belt and Xiamulun molybdenum polymetal metallogenic belt on the northern margin of North China Craton.Molybdenite mineralization developed in the granite porphyry of the deposit.The precise dating of the rock-forming and molybdenum mineralization in Hongshanzi uranium-molybdenum deposit were studied in this paper.The Re-Os dating of molybdenite from the ore bodies yields the model ages of(137.2±3.2)Ma and(138.2±2.1)Ma,and the SHIRMP U-Pb dating of the zircon from granite porphyry gives an age of(133.1±1.2)Ma.Those ages indicate that rock-forming of granite porphyry and the molybdenum mineralization are approximately at the same time,and they all occurred in the Early Cretaceous.In addition,the Re content of molybdenite ranges from 186.6×10^(-6) to 216.8×10^(-6),indicating that the ore-forming material derived from the mantle.According to the comprehesive analysis on the Xilamulun molybdenum polymetallic metallogenic belt,it was believed that the molybdenum mineralization in the granite porphyry of the Hongshanzi uranium-molybdenum deposit had the characteristics of porphyry-type molybdenum mineralization,and fail into the 138 Ma metallogenic phase of the belt.Based on the tectonic history of the area,molybdenum mineralization is the result of the implacement of ore-beare mantle fluid formed interaction of mantle component and lithosphere during the Cretaceous lithosphere thinning process of North China Craton.

关 键 词：辉钼矿 RE-OS年龄 锆石SHRIMP U-Pb定年 铀钼矿床 红山子 

分 类 号：P578.291[天文地球—矿物学] P619.14[天文地球—地质学]