试论广西靖西县新圩铝土矿区堆积型铝土矿体的分布特征

靖西堆积型铝土矿,就是指其境内赋存于上二叠统合山组底部古风化壳型铝土矿（亦称原生铝土矿）,在新生代的表生条件下,遭受长期性的岩溶作用和红土化作用,使原生铝土矿剥蚀、崩落、迁移,同碳酸盐岩的溶蚀残留物堆积于岩溶洼地、谷地中或缓坡上的一套含铝土矿的堆积组合物。堆积型铝土矿主要分布在以石炭系、二叠系下统地层为基底的岩溶洼地及缓坡地上。堆积铝土矿体的形成、规模、含矿率、矿石质量受原生沉积铝土矿体、岩溶洼地大小、矿源层所处位置、地形地貌及地层等因素控制。峰丛洼地是堆积铝土矿最主要的分布区段;原生铝土矿体规模越大,则形成的堆积铝土矿体规模越大;含矿洼地封闭性较好,则矿体厚度大,含矿率较高。

Distribution characteristics of accumulative bauxite orebodies in Xinyu bauxite field of Jingxi, Guangxi

Jingxi accumulative bauxite,namely the paleo-crust of weathering type bauxite（or primary bauxite） occurring at the bottom of Heshan formation in upper Permian system of the region,was accumulated in karst depression,valley or on gentle slope as a set of bauxite bearing compound accumulation with corrosion residue of carbonate rocks,through denudation,collapse and transportation of primary bauxite deposit,subject to long term karst process and laterization,under surface environment of Cenozoic Era.Accumulative bauxite mainly occurs in karst depression and on gentle slope based on the strata of Carboniferous,Lower Permian system.The formation,scale,ore bearing rate and ore quality were all controlled by the factors such as primary bauxite orebody,scale of karst depression,the location of ore source,relief and stratum etc.Peak forest depression is the major distribution section for accumulative bauxite.The larger the primary bauxite orebody was,the better for a large scale accumulative bauxite orebody formed.If the ore bearing depression is relatively closed system,orebody would be thicker and ore bearing rate is higher.