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明则斑岩钼矿床位于冈底斯成矿带的东南缘,雅鲁藏布江缝合带北侧。矿区内主要出露有钾长花岗岩、黑云母二长花岗岩、花岗闪长岩、似斑状二长花岗岩及花岗斑岩,其中花岗斑岩为成矿岩体。围岩蚀变较为强烈,主要的蚀变特征有:钾化、硅化、绿泥石化、高岭土化和矽卡岩化,而且各种蚀变现象具有垂向分带特征,其中矽卡岩化主要发育在地表浅部,岩体与地层的接触部位,形成了石榴石、透辉石、绿帘石等矽卡岩矿物,而钾化、硅化等蚀变分布在相对较深的部位。矿化类型主要是斑岩型和矽卡岩型矿化,具有垂向分带的特征,上部是矽卡岩型铜矿化和弱的钨矿化,下部斑岩型的铜钼矿化,其中斑岩型的矿化也具有垂向分带特征,铜矿化分布在相对上部,钼矿化分布在相对靠下的深部区域。矿石主要以块状、细脉浸染状和浸染状为主,矿石矿物主要有辉钼矿、黄铜矿、黄铁矿、白钨矿和少量的斑铜矿。选取钻孔中新鲜的黑云母二长花岗岩中穿插的黑云母-黄铁矿脉,对其中的黑云母进行40Ar-39Ar定年,得到坪年龄为28.2±0.33Ma,该年龄值与辉钼矿的Re-Os年龄相吻合。同时结合冈底斯南带上已知的成矿时代,说明整个冈底斯东段南带的成矿时代可能是介于30.26～23.62Ma之间,这明显不同于冈底斯东段北带和中带的斑岩型或斑岩-矽卡岩型矿床,说明在冈底斯成矿带东部除发育有后碰撞阶段的斑岩型铜(钼)或铜多金属矿床外,还发育有晚碰撞阶段的成矿作用。对明则斑岩钼矿成矿时代的厘定,为深入研究冈底斯成矿带的多期次成矿及冈底斯成矿带与板块俯冲到碰撞再到碰撞后伸展的构造岩浆活动有关的成矿演化过程提供了有力的支持。
The Ming porphyry molybdenum deposit is located in the southeastern margin of the Gangdese metallogenic belt and to the north of the Brahmaputra suture zone. Mainly exposed in the mining area are potassium long granite, biotite monzogranite, granodiorite, like porphyritic monzonitic granite and granite porphyry, in which the granite porphyry is a metallogenic rock. The alteration of wall rocks is more intense. The main alteration features are: potash, silicification, chloritization, kaolinization and skarnization, and the various alteration phenomena have vertical zonation. Among them, skarnization is mainly Developed in the shallow surface of the earth, the contact between rock mass and formation, the formation of garnets, diopside, epidote and other skarn minerals, and potassium, silicification and other alterations in the distribution of relatively deep parts. The types of mineralization are mainly porphyry and skarn-type mineralization with vertical zoning characteristics, the upper part is skarn copper mineralization and weak tungsten mineralization, the lower porphyry copper and molybdenum mineralization, The porphyry mineralization also has the vertical zoning characteristics, copper mineralization is located in the relative upper part, molybdenum mineralization in the relatively lower part of the deep area. Ore mainly in lumps, veinlets disseminated and disseminated dominated ore minerals are molybdenite, chalcopyrite, pyrite, scheelite and a small amount of burnt copper. The biotite-pyrite vein intercalated in the fresh biotite monzogranite from the borehole was selected to study the 40Ar-39Ar dating of the biotite in the borehole. The age of Pingbian was 28.2 ± 0.33Ma, Re-Os age match. Combined with the known metallogenic epoch of the Gangdisean belt, it shows that the mineralization age of the southern Gangdise East Belt may be between 30.26 ~ 23.62Ma, which is obviously different from the northern part of the eastern Gangdise And the mid-belt porphyry-type or porphyry-skarn deposits, indicating that in addition to the eastern Gangdese metallogenic belt in the development of post-collision porphyry-type copper (molybdenum) or copper polymetallic deposits also developed Late collision stage mineralization. The determination of the mineralization age of the Mingze porphyry molybdenum deposit is based on the further study on the multi-stage mineralization of the Gangdese metallogenic belt and the Gangdise metallogenic belt in relation to tectonic magmatism of plate subduction to collision and post-collision extension The metallogenic evolution of the process provided strong support.