铜陵大团山铜(钼)矿床辉钼矿赋存状态及成因意义

A Study of the Modes of Occurrence of Molybdenite in the Datuanshan Copper(Molybdenum) Deposit in Tongling:Implications for the Origin of the Molybdenite

大团山层状铜矿床中伴生有不同规模的钼矿体。钼矿主矿体赋存于角岩夹矽卡岩和黑色含钼碳质页岩中。矿石手标本中,矿石矿物的颗粒非常细小,难以靠肉眼或矿相显微镜进行鉴别。通过电子探针面扫描,发现钼主要以微小的鳞片状辉钼矿的形式,分布于穿插切割矽卡岩或碳质页岩的石英-方解石脉中。这类石英-方解石脉形成晚于矽卡岩或碳质页岩,通常与岩浆热液活动有关,故推断钼矿化主要与岩浆热液作用有关,辉钼矿Re-Os年龄代表着岩浆热液成矿作用的时代。

Molybdenum orebodies of various sizes are associated with the Datuanshan stratiform copper deposit. The main orebody principally exists in hornfels with skarns and molybdenum-bearing black shale. The grains of the molybdenite have always been so tiny that it is impossible to recognize them either with naked eye or even under a microscope. With the aid of an electron microprobe, the authors managed to identify the molybdenite for the first time in the ore rocks. The molybdenum exists in the form of molybdenite, and the micron-sized scale-shaped molybdenite grains are distributed in the quartz-calcite veins that cut through the skarns and black shale. This type of quartz-calcite veins, which formed after the skarn and black shale, were usually produced by magmatic-hydrothermal processes. Thus the molybdenite mineralization was probably derived from magmatic-hydrothermal fluids. The Re-Os ages of molybdenite must indicate the time of magmatic-hydrothermal mineralization in the orefleld.