(1. 中南大学 有色金属成矿预测与地质环境监测教育部重点实验室，长沙 410083； 2. 中南大学 地球科学与信息物理学院，长沙 410083； 3. 贵州省有色金属地质和核工业地质勘查局，贵阳 550005)
摘 要: 黔北铝土矿是我国超大型铝土矿矿床，该矿床为沉积型铝土矿，其成矿过程受到海平面变化的影响。通过对研究区铝土矿含矿岩系沉积相和地球化学分析，可知含矿岩系铝土矿主要形成于湖泊相滨浅湖亚相，即铝土矿形成于淡水环境，并且不同相带分布着不同结构的铝土矿；含矿岩系绿泥石黏土岩和铝土岩形成于扇三角洲和潮坪相。海平面上升旋回以绿泥石岩和铝土岩沉积为主，而海平面下降旋回以铝土矿沉积为主。海平面下降旋回的跨时远大于海平面上升旋回的跨时，这也说明铝土矿形成于漫长的风化淋滤过程。研究区铝土矿含矿岩系最多可识别出3个海平面升降旋回，这3个旋回与研究区周缘同期的碳酸盐岩和碎屑岩沉积旋回具有一致性和可对比性。
关键字: 海平面变化；铝土矿含矿岩系；湖泊相；沉积旋回；颗粒状铝土矿
（1. Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring, Ministry of Education, Central South University, Changsha 410083, China; 2. School of Geosciences and Info-physics, Central South University, Changsha 410083, China; 3. Non-ferrous Metals and Nuclear Industry Geological Exploration Bureau of Guizhou, Guiyang 550005, China）
Abstract:Qianbei bauxite deposit, which is the biggest bauxite deposit of southern China, is sedimentary type bauxite, and is affected by change of sea level. Based on the analysis of facies and geochemistry of bauxite bearing rock series in the studied area, the bauxite is known to form in shore lake and shallow lake. So, the bauxite is deposited in fresh water. The hydrodynamic condition determines types and grade of bauxite. The chlorite rock and bauxite rock are deposited in fan delta and tidal flat facies. The chlorite rock and bauxite rock are deposited during rise of sea level, and the bauxite is deposited during drop of sea level. The span of drop period is much greater than that of rise period, which explains why bauxite forming is a long weathering progress. Up to three cycles can be identified during deposit of bauxite bearing rock series, and the three cycles are consistent with corresponding period deposit of carbonate rock and clastic rock in adjacent area.
Key words: sea level change; bauxite bearing rock series; lacustrine; deposit cycle; grain bauxite
