滇黔玄武岩铜矿与北美基韦诺型铜矿对比

Comparision of Basalt Cu Deposits in Yunnan-Guizhou to the Keweenaw Cu Deposit

从地质环境、成矿特征、控矿因素等对比北美国基韦诺铜矿和滇黔玄武岩铜矿,发现有相似的一面,但差异性极大。首先,玄武岩产出背景的差异,包括溢流时限、间歇期、厚度等;其次,含矿岩系,表现为间歇期沉积砾岩、溢顶(flow-top)角砾状、杏仁状玄武岩等有利容矿岩石的缺失,不利于规模成矿;第三,根本性差异可能在于成矿作用的不同,北美矿床所处为裂谷盆地,经历了埋藏变质作用,有利于玄武岩最大化的释放铜;滇黔玄武岩没有经受变质作用,限制了铜的释放,因此,成矿条件先天不足。

This paper correlates the basalt Cu deposits in Yunnan and Guizhou with the Keweenaw Cu deposit in USA in respect to geological condition, ore-formation and ore control factors. The results show that the two differ largely in three respects. Firstly, they differ in geological background such as magma effusion time limit, inactivity period, lava thickness and so on. Secondly, they differ in ore-bearing rock series, i.e. absence of sedimentary conglomerate interlayer, flow-top breccia and amygdaloidal basalt in the basalt flow in Yunnan and Guizhou. Thirdly, there was absence of burial metamorphism of basalt in Yunnan and Guizhou.