延边东部五道沟花岗闪长岩体的年代学与地球化学特征及其成矿意义

Geochronology, geochemistry and metallogenic significance of Wudaogou granodiorite intrusion in Eastern Yanbian, NE China

为查明五道沟花岗闪长岩体与区内金、钨矿化的关系,对五道沟钨矿床的含矿花岗闪长岩进行LA-ICP-MS单颗粒锆石U-Pb定年、微量元素和稀土元素分析。研究结果表明,该花岗闪长岩体的锆石U-Pb年龄介于264-269Ma之间,加权平均年龄为（267.8±1.0）Ma,岩体的侵位时代为中二叠世;五道沟钨矿床和杨金沟金矿床的含矿岩体对侵位时代相近,地球化学特征相似,物质源区相同,应为同一岩浆作用产物;杨金沟金矿的含矿黑云母二长花岗岩与金矿石具有相似的稀土和微量元素组成,含矿岩体即为成矿岩体,而五道沟钨矿区的含矿花岗闪长岩体与白钨矿单矿物的微量元素组成具有显著差异。五道沟岩体为区内金矿的成矿岩体及含矿岩体,而对于钨矿而言,仅为含矿岩体,二者并无直接的成因联系。五道沟钨矿区的深部或外围应存在与钨矿具有成因联系的隐伏岩体。

In order to determine the genetic relationship between the intrusion and W-Au mineralization, zircon U-Pb dating by laser ablation–inductively coupled plasma–mass spectrometry（LA-ICP-MS） and trace element analysis of the ore-hosting granodiorite in the Wudaogou scheelite deposit were carried out. The results show that w（206Pb）/w（238U） ages of zircons from the granodiorite range from 264 to 269 Ma and have a weighted mean age of（267.8±1.0） Ma, demonstrating that the intrusion is emplaced in the middle Permian. The ore-hosting rocks from both the Wudaogou and Yangjingou deposit are almost simultaneously emplaced, with similar geochemical characteristics and common material source which result from the same magmatism. In the Yangjingou gold deposit, the ore-hosting monzogranite and auriferous quartz veins have almost the same trace element composition, which indicates that the ore-hosting monzogranite is metallogenic intrusion. However, compositions of trace elements in scheelite minerals from Wudaogou scheelite deposit are obviously different from those in the granodiorite. These data show that the Wudaogou intrusion is not only the ore-hosting intrusion, but also the metallogenic intrusion for gold deposits in this area, whereas there is just ore-hosting intrusion for tungsten mineralization. In other words, the Wudaogou granodiorite has no genetic relationship with tungsten mineralization. There lies another intrusion genetically associated with tungsten mineralization in the deeper or surrounding of the Wudaogou deposit.