滇西澜沧大黑山富锰蚀变岩脉的发现及其地质意义

Discovery and Geological Significance of Mn-bearing Altered Rocks from Daheishan Area,Western Yunnan Province,China

澜沧大黑山勘查区位于著名的澜沧老厂银铅锌多金属矿床南东方向约10 km。最近在大黑山勘查区内实施地质填图时发现若干条铅锌银多金属矿(化)体,并在这些矿(化)体的两侧发现与澜沧老厂银铅锌多金属矿床重要找矿标志铁锰碳酸盐化带相似的富锰蚀变带,该蚀变带主要由脉状富锰蚀变岩和围岩组成。岩石学观察显示富锰蚀变岩脉主要为由软锰矿、硬锰矿、方铅矿、方解石等组成,电子探针分析显示富锰蚀变岩脉局部铅含量高达39.53%,等离子体质谱分析显示锰单矿物中Pb含量达11.9%,Zn含量达4.36%,Ag含量达到551g/t。综合研究发现大黑山勘查区与老厂银铅锌多金属矿床在矿化元素组合、围岩蚀变类型、控矿构造条件、含矿层位等多方面具有相似性,而富锰蚀变带的发现,有望促进大黑山勘查区银铅锌多金属找矿勘查取得重大突破。

Daheishan exploration area is 10 km far from the famous Laochang Ag-Pb-Zn poly-metals deposit, Lancang area, Yunnan province, China. Recently, a few Ag-Pb-Zn poly-metals ore bodies （mineralization） have been found, surrounding those ore bides Mn-bearing altered rocks are developed, which is like Fe-Mn carbonates from Laochang deposit. The Mn-bearing altered rocks are composed of pyrolusite, psilomelane, galena and calcite, and contain Pb contents of 39.53% in some part, analyzed by EPMA. Contents of Pb, Zn and Ag in Mn minerals, analyzed by ICP-MS, are 11.9%, 4.36% and 551 g/t, respectively. Mineralization element association, wall rock alterations, ore-controlled structures and country rocks of Daheishan and Laochang area are very similar. Discovery of Mn-bearing altered rocks will promote the exploration in Daheishan area.