(1. 中南大學(xué) 有色金屬成礦預(yù)測與地質(zhì)環(huán)境監(jiān)測教育部重點(diǎn)實(shí)驗(yàn)室，長沙 410083； 2. 中南大學(xué) 地球科學(xué)與信息物理學(xué)院，長沙 410083； 3. 貴州省有色金屬地質(zhì)和核工業(yè)地質(zhì)勘查局，貴陽 550005)
摘 要: 黔北鋁土礦是我國超大型鋁土礦礦床，該礦床為沉積型鋁土礦，其成礦過程受到海平面變化的影響。通過對研究區(qū)鋁土礦含礦巖系沉積相和地球化學(xué)分析，可知含礦巖系鋁土礦主要形成于湖泊相濱淺湖亞相，即鋁土礦形成于淡水環(huán)境，并且不同相帶分布著不同結(jié)構(gòu)的鋁土礦；含礦巖系綠泥石黏土巖和鋁土巖形成于扇三角洲和潮坪相。海平面上升旋回以綠泥石巖和鋁土巖沉積為主，而海平面下降旋回以鋁土礦沉積為主。海平面下降旋回的跨時遠(yuǎn)大于海平面上升旋回的跨時，這也說明鋁土礦形成于漫長的風(fēng)化淋濾過程。研究區(qū)鋁土礦含礦巖系最多可識別出3個海平面升降旋回，這3個旋回與研究區(qū)周緣同期的碳酸鹽巖和碎屑巖沉積旋回具有一致性和可對比性。
關(guān)鍵字: 海平面變化；鋁土礦含礦巖系；湖泊相；沉積旋回；顆粒狀鋁土礦
（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
