黔北铝土矿成矿关键控制因素——海平面变化

Key control factor in ore-forming process of bauxite in northern Guizhou—Sea level changes

黔北务川−正安−道真地区(简称务正道)铝土矿的形成与海平面变化关系密切,综合运用野外地质调查、手标本观察、偏光显微镜观察、区域地层对比等手段对黔北务正道地区铝土矿矿石的自然类型与海平面变化之间的关系进行了研究。结果表明:半土状矿石层可作为长时间海退的标志;务正道地区至少经历了4次海退过程,4次大规模海退是务正道地区能形成优质铝土矿的重要原因;所有沉积型铝土矿矿石自然类型都可指示含矿岩系的沉积过程,沉积型铝土矿本身可作为一种多期次暴露标志层。

The sea level changes is an important factor which controls the forming process of the bauxite in northern Guizhou.So,a research was carried out on the relationship between sea-level changes and the natural types of bauxite ores in Wuchuan-Zhengan-Daozhen area(short for WZD)in Northern Guizhou by comprehensive use of field geological investigation,hand specimen observation,microscopic observation and regional stratigraphic correlation based on the previous studies.The results show that the natural types of ores can be regard as marker bed of sea level changes,and earthy ore bed can be seen as a sign of longstanding regression.WZD area has experienced at least 4 regressions,and the 4 large-scale regressions were an important cause for the formation of high-quality bauxite in WZD area.Land and sea transition bauxite has the similar structure features,and the natural types of ores in all the sedimentary bauxite can be used to distinguish the sedimentation cycle of the ore-bearing rock formations.The sedimentary bauxite in themselves can be regarded as a multi-stage exposure marker bed.