滇东北毛坪富锗铅锌矿床“多层位”赋矿规律及其控制机理

The ’multi-horizon’ ore-hosting regularity and ore-controlling mechanism of the Maoping Ge-rich lead-zinc deposit in the northeastern Yunnan, China

为探讨滇东毛坪富锗铅锌矿床“多层位”赋矿成因及其控矿机理,基于毛坪矿区内坑道和钻孔岩心的详细编录,开展了构造-蚀变岩相学填图和矿床精细解剖,总结了该矿床的“多层位”赋矿岩性组合特征。结果表明,除构造控矿因素外,“蚀变碳酸盐岩+碎屑岩建造”特殊岩性组合是矿床“多层位”的主控因素之一,该岩性组合包括上泥盆统宰格组(D_(3)zg)蚀变白云岩与下石炭统大塘组(C_(1)d)砂页岩遮挡层、摆佐组(C_(1)b)蚀变白云岩与其顶部的绿色页岩遮挡层、上石炭统威宁组(C_(2)w)蚀变白云岩(灰岩)与中二叠统梁山组(P_(2)l)砂页岩遮挡层。研究认为,构造控制了成矿流体运移和聚集成矿的场所,而“多层位”的特殊岩性组合具有圈闭成矿流体的作用,同时也是成矿流体集聚的有利部位。构造运矿(液)、特殊岩性组合存矿是毛坪富锗铅锌矿床“多层位”赋矿的主要控矿机理。

In order to explore the ‘multi-horizon’ ore-hosting genesis and ore-controlling mechanism of the Maoping Ge-rich lead-zinc deposit in the northeastern Yunnan, based on the detailed logging of underground adits and borehole cores of the Maoping deposit, in this paper, we have carried out structural-altered lithofacies mapping and careful anatomy of the deposit and have summarized characteristics of the ‘multi-horizon’ ore-bearing lithological association of the deposit. The results show that besides the structural ore-controlling factor, the special lithological combination of ’altered carbonate rock + clastic rock formation’ is one of the main controlling factors of the ‘multi-horizon’ore-hosting deposits. There are lithological combinations including altered dolomite of the Upper Devonian Zaige Formation(D_(3)zg) and sandy shale(barrier layer) of the Lower Carboniferous Datang Formation(C_(1)d), altered dolomite and its overlayered green shale(barrier layer) of the Lower Carboniferous Baizuo Formation(C_(1)b), and altered dolomite(limestone)of the Upper Carboniferous Weining Formation(C_(2)w) and sand shale(barrier layer) of the Middle Permian Liangshan Formation(P_(2)l). In general, it is believed that the structures had controlled the migration and accumulation of ore-forming fluid, and the ‘multi-horizon’ special lithologic combinations are favorable places for the entrapment and accumulation of ore-forming fluids. ’The transportation of ore-forming materials(fluids) by structures and the ore-hosting by special lithological combinations’ is the main ore-controlling mechanism for the ’multi-horizon’ ore-hosting genesis of the Maoping Ge-rich lead-zinc deposit.