江西梅树坪钨钼矿床地质、成岩成矿时代与找矿方向

Geological characteristics,rock and ore forming age and prospecting of Meishuping tungsten-molybdenum deposit in Jiangxi

梅树坪钨钼矿床位于南岭成矿带崇余犹矿集区内,矿体发育于九龙脑岩体南缘接触带,构造上受北北东向断裂控制,矿化类型主要为石英脉型钨钼矿化,并发现了细粒花岗岩中浸染状白钨矿化,与成矿有关的岩浆岩以中粗粒斑状黑云母花岗岩为主。本文在矿床地质工作基础上,利用LA-ICP-MS锆石U-Pb法获得中粗粒斑状黑云母花岗岩的年龄为(157.2±1.70)Ma;并利用辉钼矿Re-Os同位素测年,获得黑钨矿化石英脉中的辉钼矿的年龄为(156.2±0.93)Ma。研究表明梅树坪花岗质岩浆活动与成矿作用基本同时,均为燕山晚期,成矿紧随岩浆就位发生。结合前人的研究成果,梅树坪钨钼矿与华南地区钨多金属大规模成矿作用时间150~160 Ma一致。梅树坪钨矿与西华山钨矿等具有相同的成矿时代、成矿背景和相似的成矿条件,预测矿区隐伏岩体南延之内接触带和震旦系变质砂岩外接触带具有很好的找矿潜力。

The Meishuping W-Mo deposit is located in Chong-Yu-You ore-concentrated area, eastern of the Nanling metallogenic belt. The orehodies occurred in southern contact zone of the Jiulongnao batholith. The orebodies, which are of quartz-vein-type extending in east-west, are controlled by NNE-trending faults. Disseminated scheelite was observed in the fine-grained granite, and medium-coarse-grained porphyritic biotite granite is mainly the ore-forming granite. Based on the studies of deposit geological work, the LA ICP-MS zircon U-Pb and molybdenite Re-Os dating have been carried out to accurately determine the ages of the granite emplacement and W mineralization. The zircon U-Pb age of mineralized pluton is 157. 2--4-1.70 Ma. The Re-Os age of molybdenite within mineralized quartz vein is 156.2＋0. 93 Ma. These results show that the Meishuping granitic magmatism and mineralization occurred nearly at the same time. According to the previous research data, Meishuping W-Mo deposit has the similar metallogenic time of 150 - 160 Ma as that of the tungsten- polymetallic deposits in Nanling region. Meishuping tungsten deposit and Xihuashan tungsten deposit have the same metallogenic epoch and metallogenic background and similar metallogenic conditions. We predict that the mining area of hidden rock mass within the south inner contact zone and metamorphic sandstone outer contact zone have very good prospecting potential.