黔中沉积型铝土矿成矿模式

A Genetic Model for Sedimentary Type of Bauxite Deposits in Central Guizhou

本文根据１９８８～１９９１年在黔中一带对铝土矿成因的详细研究资料，指出：黔中铝土矿主要是由古红土型风化壳物质的冲洪积砂体，在有腐殖酸参与的大气降水陆解作用下，经历再次富铝脱硅去铁改造而成；不同形态的矿体产于不同的古岩溶负地形中，大型铝土矿床一般皆赋存于大型古岩溶负地形的冲洪积扇群中尾部及扇三角洲沉积中。最后提出了黔中铝土矿的成矿模式。

For a long time,there have been miscellaneous theories on the origin and formation of the bauxite deposits in central Guizhou,such as neritic deposition as colloid, fresh-lagoonal colloid deposition, palaeolateritic weathering crust enrichment and so on, which are, in author's opinion, not all the most convincing explanations to this mineralization. In this paper,it is suggested that the bauxite concentration was resulted mainly from the further desilification of the sandy alluvium and/or pluvium derived from previous latentic type of palaeoweathering crusts, on the basis of the detailed studies, in a period of 1988 to 1991, of geologic and geomorphologiclsetting for sedimentation, of the source of bauxite materials,of ore-forming phases,and of ore-forming mechanism,along with the expeirments simulating the ore-forming process.This desilification took place obviously in combination with activity of the humic acid and aquatolysis of the precipitate water. As a result, there are a gerat many different shapes of bauxite orebodies which developed on the negative reliefs of ancient karst areas, while those in larger size occur generally within the sediments at the medium-end of the alluvial-pluvial aprons or in fan deltas. Moreover, a metallogenic model for the bauxite deposits is proposed here, which may cover the similar bauxite ore deposits occuring in other places of the central area of Guizhou.