贵州省岩风阡铝土矿床成因及成矿模型初探

岩风阡铝土矿是近年来在黔北地区新发现的大型铝土矿床。矿体多呈层状、似层状,赋存在上石炭统大竹园组(C_2d)中下部,产状稳定,厚度变化小。矿石具有碎屑、豆或鲕状、泥、粉晶结构和半土状、块状和致密块状构造等典型沉积组构。结合成矿物质来源、古成矿环境,表明岩风阡铝土矿为沉积型矿床。通过分析成矿过程,建立其成矿模式,认为广西运动使黔北地区上升为陆,韩家店组(S_1hj)页岩在湿热气候条件下,风化形成铝土矿"初始富集"的铁铝质古红土型风化壳,再经晚石炭世海侵作用,形成了含铝岩系的雏形。早—中二叠世的再次暴露,使"初始富集"的含铝岩系再次经历淋滤、富集,进而成矿。

A preliminary study on genesis and metallogenic model of Yanfengqian Bauxite Ore Deposit in Guizhou Province

Yanfengqian Bauxite Ore Deposit is a newly discovered large-scale deposit in northern Guizhou Province. The ore bodies of Yanfengqian Bauxite Ore Deposit, with stable occurrence and small variability in thickness, are broadly bedded or quasi-bedded, which mainly occurred in the lower-middle part of Dazhuyuan Formation (C2d). The ores are of clastic, pisolitic or oolitic, microscale politic and aleuritic texture, while the structure are dominated by earthy erthy, massive and dense massive structure, which both are typical texture and structure formed by sedimentation. Combined with sources of the metallogenetic material and paleo-metallogenetic environment, it indicates that Yanfengqian Bauxite Ore Deposit is a sedimentary-type bauxite deposit. Through the analysis of metallogenic process, we set up its metallogenic model: the northern area of Guizhou Province were raised to be land by Guangxi Movement, and Hanjiadian Formation (S1hj) was weathered to be ferroaluminum paleo-lateritic-type weathering crust under sub-tropical and tropical climate, which made the bauxite be preliminary enrichment. Affected by the transgression in late Carboniferous, the paleo-weathering crust transformed into the original aluminiferous rock series. In early-middle Permain, the aluminiferous rock series exposed to land again, which result to the bauxite eluviation and enriched again, then mineralized.