贵州“红土型”金矿成因类型新说

New recognization on genesis of “lateritic type” gold deposit in Guizhou

在贵州的西南部地区已探明了几处大、中型赋存于第四系松散堆积层中残坡积型金矿床 ,它具有分布广、规模大及品位较低和暴露地表易采选的特点。在邻近的云南、广西地区也有发现。在此之前 ,其成因类型被认为是红土型金矿。根椐最近的成矿区划、科研、勘查等资料证实 ,该类型金矿是微细浸染型岩金矿床作为矿源地质体经近地表风化堆积形成。矿床具有特殊的风化、堆积、保存条件。矿体形态受下伏茅口组古今岩溶喀斯特形态的制约 ,金的含量总体有从原矿石到残坡积氧化矿石变贫的趋势 ,由此提出风化残积成因类型的新认识。从该类矿床形成机理的观点出发 ,提出在风化形成的残坡积型金矿床附近寻找微细浸染型金矿床。

Several large and middle residual gold deposits hosted in Quaternary accumulation layer have been discovered in southwest of Guizhou. They have the characteristics of wide distribution, large scale, lower grade easy mining and benefication. This type of deposit has also been found in adjacent Yunnan and Guangxi. The genesis used to be regarded as lateritic. According to the recent regionalism, research and exploration, this type of gold deposit belongs to fine disseminated type accumulated by near surface weatheringas source geologic body. The deposit has special conditions of weathering,accumulation and preservation. The shape of orebody is controlled by that of underlying Maokou group, ancient and modern karst. Gold content genarally has a decline trent from crude ore to residual oxidized ore. Therefore new recognization of weathering residual genesis has been proposed. Based on the forming mechanism of this type, it indicates that fine disseminated gold deposit is probably hosted near the weathering residual gold deposit.