矿床地质2025，Vol.44Issue(3)：617-634,18.DOI:10.16111/j.0258-7106.2025.03.006
桂西沉积型铝土矿—水硬铝石形成机制
Formation mechanism of diaspore in sedimentary bauxite from western Guangxi,China:A case study of Donglan-Bama-Fengshan area
摘要
Abstract
Diaspore is the main mineral component of sedimentary bauxite ore,and its genetic mechanism remains un-clear,which limits the comprehensive understanding of the sedimentary bauxite mineralization process.The Donglan-Bama-Fengshan metallogenic area is one of the main sedimentary bauxite mining areas in western Guangxi,China.In this research,the sedimentary bauxite in Donglan-Bama-Fengshan metallogenic area was tak-en as the research object.On the basis of field geological investigation,petrographic observation,X-ray diffrac-tion(XRD),and scanning electron microscopy with energy dispersive analysis(SEM-EDS)were used to explore the formation mechanism of diaspore.The analysis results show that the bauxite in the Donglan-Bama-Fengshan metallogenic area is mainly composed of diaspore,pyrophyllite,kaolinite,goethite,pyrite,anatase,etc.The re-sults of SEM-EDS analysis show that Fe,Si,Ti,and other elements exist in diaspore generally.Fine-grained ana-tase is widely present in diaspore crystals.There are no signs of metamorphism in the hanging and foot wall lime-stone of bauxite ore-bearing rock series in the Donglan-Bama-Fengshan metallogenic area,which indicates that the genesis of the diaspore is simple crystalline.Under the favorable leaching and monsoon climate,plenty of alu-minum ions were hydrolyzed from clay minerals.The seawater flooded the carbonate platform resulted in the re-ducing environment inside the platform.The ore-forming water appeared alkaline due to the alkaline geochemical barrier of foot wall-rock limestone and the uplift of groundwater.Under the alkaline and reducing conditions,alu-minum ions crystallized to form diaspore.The formation of diaspore in the Donglan-Bama-Fengshan metalloge-nic area went through four ore-forming stages:Material preparation,weathering,deposition and compaction.The early generation of diaspore was formed in the weathering stage,and the late generation of diaspore was formed in the deposition stage.A part of diaspore had late reformation forming kaolinite by siliceous fluid metasomatism.关键词
沉积型铝土矿/一水硬铝石/形成机制/东兰-巴马-凤山成矿区/桂西Key words
sedimentary bauxite/diaspore/formation mechanism/Donglan-Bama-Fengshan metallogenic area/western Guangxi分类
地质学引用本文复制引用
罗靖伟,庞保成,许箭琪,向绍立,卢光辉,徐海棚,姚双秋..桂西沉积型铝土矿—水硬铝石形成机制[J].矿床地质,2025,44(3):617-634,18.基金项目
本文得到国家自然科学基金项目(编号:41362006)资助 （编号:41362006）
