老挝爬奔金矿围岩蚀变特征及其与金矿化的关系

摘要

Phapon gold deposit is located in the west of central Laungprabang island arc. Ore body occurs in thick-huge thick limestone in Carbonic-Lower Permian and controlled by the NW-NNW striking faults . It is middle-low temperature hydrothermal deposit. On the basis of the field geological investigation, mineral micro-structure study and the alterated rock element content, we studied the correlation of wall rock alteration with gold mineralization. It is suggested that wall rock alteration takes middle-low temperature alterated mineral association as silicide, limonite, siderite ore and calcite.With alteration strength increasing, the Au, Si and Fe elements are increasing, but Ca decreasing. The alteration is controlled by faults, and the alternation is with obviously zones, which formed different ore types. Multiple alternation overlay is favorable for mineralization. The unique wall rock alternation of“redden”and“bleaching”is obviously indicator for deposit, which will guide for gold prospecting both in periphery and adjacent areas by combining with the structure, stratum and geochemical anomaly.%爬奔金矿位于琅勃拉邦岛弧带中段西侧，矿体赋存于石炭-下二叠统厚层-巨厚层灰岩中，受NW－NNW向断裂构造控制,是少硫化物型中-低温热液矿床。野外调研及室内研究结果表明：爬奔金矿的围岩蚀变以中－低温蚀变矿物组合为特征，主要有硅化、褐铁矿化、菱铁矿化、方解石化，随着岩石蚀变强度的增加，Au与Si、Fe同步增加，而Ca减少。蚀变受断裂构造控制，分带明显，不同的矿化蚀变对应不同的矿石类型。多种蚀变叠加部位是成矿有利地段。“红化”蚀变和“褪色”蚀变是区内独特的围岩蚀变现象，找矿指示作用明显，结合构造、地层、化探异常等其他条件，可作为矿区外围及邻区的找矿标志。