摘要
组成黔中铝土矿的矿石矿物主要是硬水铝石,它具有胶状、它形至自形鳞片状、板片状及柱状等形态特征;其形成除少量为继承碎屑成因外,主要为胶体的晶化和粘土矿物的脱硅转化而成;划分了陆源碎屑、早期成岩、晚期成岩及表生成岩等四个阶段下矿物的共生组合,并讨论了矿物的生成及转化关系和铝土矿的形成阶段与过程。
Bauxite of Lower Carboniferous Datang formation occurred uncomformably on the karst erosion surface of Cambrian carbonate rocks in Central Guizhou Province. Ore minerals composing the bauxite are mainly diaspore and small amount of boehmite. Accessory autigenic minerals of bauxite are kaolinite, illite, and anatase, less chamosite, pyrite, hematite, and geothite. In addition, a few terrigeous clastic minerals can be found in the bauxite.Diaspore is the main ore mineral in Central Guizhou Province. Based on analyses of SEM, infrared absorption spectra, X-ray diffraction and electron probe, in the paper a special emphasis is given on characteristics of diaspore. The morphologic features of diaspore are colloidal, Xenomorphic-idiomorphic scaly, tabular and prismatic crystals, which reflect a continuous process of sedimentary colloform crystallization in the diagenetic stage. Formation of diaspore was mainly an amorphous gel crystallization, secondly transformation of clay minerals such as kaolinite, and thirdly to less extent clastic genesis.According to mineral composition of bauxite, four stages for mineral associations, including terrigeneous clastic , early diagenetic, late diagenetic and epidiagenetic stages are distinguished. Furthermore, formation of minerals and their transformation relations are discussed. Finally, the authers suggest that the bauxite in Central Guizhou Province was formed by sedimentation and then became a higher-grade bauxie after a series of post-diagenetic reworkings, such as desilification, deferrification and aluminum enrichment, and weathering, leaching and recrystallzation during epidiagenesis.
出处
《地质科学》
CAS
CSCD
北大核心
1992年第A12期226-239,共14页
Chinese Journal of Geology(Scientia Geologica Sinica)
基金
国家自然科学基金
关键词
铝土矿
硬水铝石
晶体
矿物
Bauxite, Diaspore, Crystal morphology, Central Guizhou Province.
