摘要： 黔北务正道(务川—正安—道真)地区,早二叠世沉积型铝土矿形成于黔北平原近海的一个半封闭海湾环境,冰期低海平面时期与中扬子海湾分离成为滨岸湖泊,间冰期高海平面时期与中扬子海湾连通。古地理单元可分为黔北平原、滨岸平原、滨岸湿地和半封闭海湾等单元。准同生和后期含矿岩系的暴露、淋滤是铝土矿形成的主要控制因素。土状及半土状铝土矿(包括土状及半土状的碎屑和豆鲕矿石)是含矿岩系准同生和后期暴露期间淋滤而成的,而致密状矿石是没有经过淋滤或弱淋滤形成的。碎屑状铝土矿是盆地内部泥裂破碎再沉积形成的;豆鲕状矿石是盆地内部胶体凝聚而成的。务正道铝土矿的动态成矿模式表明铝土矿主要形成于两次准同生淋滤期,因此铝土矿找矿应重点选择滨岸湿地、具有明显淋滤作用发育的地区。

关键词: 贵州省, 二叠系, 铝土矿, 成矿模式

Abstract: The Early Permian sedimentary bauxite deposits of Wuchuan-Zheng′an-Daozhen area in the northern Guizhou Province formed in a half-closed bay near the North Guizhou Plain. During the low sea-level in the glaciations,the bay was separated from the Middle Yangtze Bay and became a seashore lake;in interglaciations,the rising sea-level made the area to connect to the Middle Yangtze Bay again. The area can be divided into four palaeographic anits, i.e., North Guizhou Plain,seashore plain,seashore wetland and half-closed bay.The bauxite mineralization was mainly controlled by penecontemporaneous and/or contemporaneous exposure and leaching process,for the earthy and half-earthy bauxite including the earthy and half-earthy pisolitic,oolitic or clastic ore formed during this period.As comparison,compact bauxite did not have or only had a weak leaching process.Clastic and pisolitic/oolitic bauxite formed through the redepositing of intrabasinal mud crack and the cohesion of intrabasinal colloid respectively.The dynamic mineralization modal of bauxite in Wuchuan-Zhengan-Daozhen area indicate that two periods of the penecontemporaneous leaching are the main metallogenic epoch of the bauxite and the palaeogeographical seashore wetland with intense leaching process is the metallogenic prospect district.

Key words: Guizhou Province, Permian, bauxite, mineralization model

中图分类号: 

• P588A