贵州中部铝土矿沉积环境特征研究进展

Research on Characteristics of Bauxite Sediment Environment in Central Guizhou

摘要: 贵州中部的铝土矿资源较多，对本区铝土矿的研究，前人的研究多侧重于成矿作用方面，对沉积环境方面的研究相对较少。再者，对黔中铝土矿成矿区边缘部分的研究相对薄弱。针对此现状，本次研究以含矿岩系沉积特征、地球化学特征作为研究内容，对贵州中部典型地区及其边缘部分铝土矿含矿岩系沉积环境进行分析，贵州中部铝土矿主要以致密状、碎屑状、豆鲕状铝土矿和含铝质粘土岩富集于九架炉组中，其含矿岩系可分为铁质岩段和铝质岩段。铝土矿在本区中部比边缘地区更为富集，矿石质量在中部地区也较边缘地区好。各地区的主量元素Al和Ti、Fe、Si元素的关系有所差异，说明受风化作用影响较大；Sr/Ba、Th/U、δCe等元素含量和稀土元素反映出贵州中部铝土矿的沉积环境可能处于从南至北受海水的影响由强到弱，氧化由弱变强而还原性由强变弱的趋势。结合含矿岩系特征以及地球化学对沉积环境的指示意义，表明贵州中部铝土矿铝土矿的沉积环境从南到北氧化性逐渐增强而还原性逐渐减弱，受海水的影响作用逐渐变小，成矿过程主要发生于从南至北由海陆过渡相沉积环境过渡至陆相沉积环境中。

Abstract: The bauxite resources in central Guizhou are relatively abundant. Previous studies on bauxite in this region have mostly focused on mineralization, with relatively little research on sedimentary environments. Furthermore, studies on the marginal parts of the bauxite metallogenic district in central Guizhou are comparatively weak. In response to this situation, this study takes the sedimentary characteristics and geochemical characteristics of the ore-bearing rock series as research contents to analyze the sedimentary environment of the bauxite ore-bearing rock series in typical areas and their marginal parts in central Guizhou. The bauxite in central Guizhou is mainly enriched in the Jiujialu Formation in the form of dense, clastic, oolitic and pisolitic bauxite and aluminum-bearing clay rocks. Its ore-bearing rock series can be divided into a ferruginous rock member and an aluminous rock member. Bauxite is more enriched in the central part of this region than in the marginal areas, and the ore quality is also better in the central part than in the marginal areas. The relationships among major elements Al, Ti, Fe, and Si vary in different areas, indicating a significant influence from weathering. The contents of elements such as Sr/Ba, Th/U, δCe, and rare earth elements indicate that the sedimentary environment of bauxite in central Guizhou may exhibit a trend from south to north, where the influence of seawater decreases from strong to weak, oxidation changes from weak to strong, and reduction changes from strong to weak. Combined with the characteristics of the ore-bearing rock series and the indicative significance of geochemistry for sedimentary environments, it is suggested that the sedimentary environment of bauxite in central Guizhou gradually becomes more oxidizing and less reducing from south to north, with the influence of seawater gradually decreasing. The ore-forming process mainly occurred in a transitional environment from marine-continental transitional facies to continental facies from south to north.