猫场式黄铁矿矿床地质特征及成因探讨

在川滇黔交界地区二叠系峨眉山玄武岩被边缘地带,广泛分布着猫场式黄铁矿矿床(图1)。这一类型矿床具有典型特征,其成矿与峨眉山期火山岩密切相关,展布稳定,厚度大,品位较高,为我国西南硫矿带中佼佼者,颇具经济意义和地质找矿意义。

Geological characteristics and genetic investigation of the Maochang type pyrite deposits

Widely distributed along the edge zone of the Permian Emeishan basalt covering layer are Maochang type pyrite deposits, deposits of typical significance whose formation is closely asscoiated with Emeishan volcanic rocks. These deposits are characterized by stable distribution, great thickness and relatively high grade and therefore have noticeable importance in economy as well as in mineral exploration. The Maoehang type pyrite deposits occur in altered basalt, distributed as a zone 150 km in length and 10-20 km in width. Orebodies are bedded or stratoid in shape, stable in extension and 1.5-3 m in thickness, and have low harmful components. The ore-bearing country rocks, subjected chiefly to clay grouting, have SiO₂, Al₂O₃ and TiO₂ as their major chemical composition and pyrite as their main mineral constituent with marcasite concentrated on Icoal basis. The Maochang type pyrite is intimately related to the volcanic activities of the Emeishan epoch in genesis, being derivative of sulfur-rich basaltic magma. The mineralization took place mainly in more-alkaline littoral-shallow sea platform environment with low oxidation potential; the sea water played the role of cushioning and seal, making it possible to preserve ore-bearing volatiles and produce pyrite through mineralization. The formation of the ore deposit was strictly governed by the volcanism, the ring-like volcanism were distributed regularly in zonation, the ore materials were predominantly derived from volcanic exhalation, and the pyrite deposits were eventually formed throngh sea bed hydrothermal sedimentation. It is therefore concluded that the Maochang type pyrite deposits belong genetically to hydrothermal-sedimentary deposits related to Emeishan basalt.