赣南樟(东坑)-九(龙脑)钨多金属矿床矿物学、年代学特征及其地质意义

Mineralogical and geochronological characteristics of the Zhang(dongkeng)-Jiu(longnao)tungsten polymetallic deposit,southern Jiangxi Province,and its geological implications

樟(东坑)-九(龙脑)钨矿位于南岭成矿带东段,是赣南崇-余-犹世界级钨多金属矿集区的重要组成部分。矿床分樟东坑和九龙脑两个矿段,前者以外带石英脉钨钼矿化为主、后者以内带石英脉型钨矿化为主,是赣南地区"五层楼+地下室"找矿模型侧向分带的典型代表。本文在矿床地质调查基础上,对内外接触带矿物组合进行了系统对比,并对其中黑钨矿开展了电子探针测试,同时测定了与成矿密切相关的黑云母花岗岩体锆石U-Pb年龄。结果表明九龙脑矿区的成岩年龄为(151.1±2.2)Ma,与其内、外带矿体成矿年龄(分别为151.1 Ma和151.3 Ma)在误差范围内高度一致,表明成岩与成矿作用基本同步。内、外带黑钨矿矿物化学成分连续,Mn-Fe含量呈明显线性相关,为同一次岩浆热液成矿作用产物。外带黑钨矿较内带黑钨矿Fe/Mn值偏高,反映外带矿体成矿温度高于内带矿体。基于上述研究成果,本文建立了樟东坑-九龙脑钨矿成矿模型,并提出了下一步找矿方向。

Zhang （dongkeng）- Jiu （longnao） tungsten polymetallic deposit, located in east section of Nanling region, is an important part of the Chongyi - Dayu - Shangyou concentrated mineral area. The deposit clustered mainly in Zhangdongkeng section and Jiulongnao section, which respectively have ＂outer mineralized quartz vein＂ and ＂inner mineralized quartz vein＂, is considered to be a typical example of ＂Five levels ＋ Basement＂ model. Based on the scientific research project of ore deposit geology, the author carried out a systematic comparison on the mineral assemblage of the inner and outer contact zone, the electron microprobe test of wolframite, and the zircon U-Pb dating of biotite granite rock mass which is closely related to mineralizatioru The zircon U-Pb average isochron age is 151.1-2.2 Ma and reflects the diagenetic age of the Jiulongnao mining area. That is highly consistent within the error range of mineralization age of internal ore body （151.1 Ma） and external ore body （151.3 Ma）. The results show that Zhang-Jiu granitic magmatism and mineralization occurred nearly at the same time. Electron microprobe analysis shows that there is a linear relationship between Mn and Fe, therefore, the inner quartz vein and outer quartz vein could be considered as the product of the same magmatic activity. The outer ore with higher Fe/Mn ratio predicts the outer ore forming temperature is higher than the inner one. Based on the detailed study above, this paper establishes the metallogenic model and makes a prospecting direction.