贵州务川-正安-道真地区铝土矿产出地质特征

贵州务川-正安-道真地区铝土矿,目前共发现2个超大型矿床、9个大型矿床、14个中型矿床,估算各级资源储量7×10~8余t,是贵州乃至全国重要铝土矿产出地。本区含矿岩系与上覆中二叠统梁山组之间有明显的沉积间断;区内含矿岩系岩石类型主要由粘土岩类、铝质岩类和铁质岩类组合而成;矿体赋存在上石炭统大竹园组的中上部,与铝土岩和粘土岩共生,矿体产状与岩层产状一致,矿体形态以层状、似层状为主;矿石自然类型有灰白、浅灰色碎屑状至土状铝土矿,灰、深灰色致密状铝土矿和灰色豆鲕状铝土矿3种;矿石结构有碎屑结构、豆鲕结构、泥晶结构、粉晶结构和碎屑—豆粒复合结构等5种类型,矿石构造有块状和半土状两种构造。通过含矿岩系含矿岩系时代特征、岩石类型、剖面类型、厚度变化及底板灰岩变化、矿体产出形态、矿石的结构、构造等特征阐述,总结了贵州务川-正安-道真地区铝土矿的产出特征。

Geological Characteristics of Bauxite Deposits in Wuchuan-Zheng′an-Daozhen Area,Guizhou Province

The Wuchuan-Zheng′an-Daozhen bauxite metallogenic belt is an important bauxite concentration area in Guizhou, and even in China. Up to today, 2 super large scale deposits, 9 super scale deposits and 14 medium scale deposits have been explored in this belt, while the calculated resource reserve has increased to more than 700 million tons. According to palaeo-pollens, the ore-bearing rock series is Upper Carboniferous, and it is unconformable with overlying Middle Permian Liangshan Formation; according to fossils. The ore-bearing rock series are mainly composed of clay rock, bauxite rock ferriferous rock. The ore bodies coexist with bauxite and clay rocks, and distribute in middle-upper section of Upper Carboniferous Dazhuyuan Formation. The ore bodies emerge as bedded, parabedded, lenticular shapes and are consistent with the occurrence of their surrounding rocks. The natural types of the bauxite are hoary and grayish clastic-earthy bauxite, gray and dark gray dense bauxite and gray pisolitic bauxite. The ore textures include clastic texture, oolitic texture, mud grain texture, powder grain texture, clastic- pisolitic composite texture; the ore structures include massive structure and semi-earthy structure. The geological characteristics of bauxite deposits have been summarized basing on comprehensive studies of metallogenic epoch, rock types, profile types, thickness variation, floor limestone changes, ore bodies morphology, ore textures and ore structures in Wuchuan-Zheng′an-Daozhen bauxite metallogenic belt.