滇黔交界地区玄武岩铜矿蚀变分带和有机包裹体特征及其地质意义

Alteration Zoning and Organic Fluid Inclusions in Basalt Copper Deposits in Northeastern Yunnan and Western Guizhou and Their Geological Significance

在滇黔交界地区的峨眉山玄武岩铜矿中除了发现大量沥青外,还在与沥青共生的石英中发现了由液态烃、固体沥青和气相组成的有机包裹体,表明沥青直接来自石油。在钻孔柱状剖面图上,矿化蚀变具有自下而上依次为辉铜矿化、沥青化和自然铜矿化的分带性,且沥青和自然铜的分布位置大体一致,表明自然铜矿化与沥青关系密切。这些特征表明:本区曾发育过古油气藏,该古油气藏不仅为铜矿化提供了储集空间,而且导致了上为自然铜、下为辉铜矿的铜矿化空间分带,自然铜矿化与古石油的强还原作用有关。

Besides bitumen, a lot of organic fluid inclusions composed of liquid hydrocarbon, solid bitumen and gas are discovered in quartz from basalt copper ores in northeastern Yunnan and western Guizhou, suggesting that the bitumen directly came from crude oil. According to the logs of dill holes, the mineralization and alteration are zoned vertically： native copper in upper part and chalcocite in lower part. The location of bitumen is consistent with that of native copper very well, showing their close genetic association. However, the location of some native copper is higher than bitumen. All the above suggest that there had been petroleum--gas reservoir in the lower part of the Fourth Member of the Emeishan Basalt Formation of Upper Permian in the adjacent area of northeastern Yunnan and western Guizhou. The petroleum--gas reservoir not only provided structural trap for copper mineralization, but also resulted in the zoning of mineralization and alteration. Native copper resulted from strong reduced condition.