摘要： 贵州北部务川 —正安 —道真地区下二叠统大竹园组沉积型铝土矿层 ,在不同区域其下伏底板地层分别为下志留统韩家店组碎屑岩及上石炭统黄龙组灰岩 ,因此对铝土矿层的成矿物质来源一直存疑。对韩家店组薄层砂岩夹层及大竹园组铝土矿层样品的碎屑锆石年代学分析表明 ,两者的锆石年龄谱呈现出一致性 ,且该碎屑锆石年龄谱与华夏陆块基底地层具有明显亲缘性。以上结果证明 ,韩家店组碎屑岩的红土化风化产物为铝土矿层的成矿母质提供了物质来源。而从铝土矿层与黄龙组灰岩的假整合接触关系及钻孔中出现的黄龙组灰岩次生岩溶角砾现象可知 ,黄龙组灰岩同样为该矿层提供了物源。因此 ,大竹园组铝土矿层具有多重物源 ,韩家店组碎屑岩可能为主要物源 ,而黄龙组灰岩在古喀斯特化过程中不仅为红土物质提供了重要的储存空间 ,也为成矿母质的积累提供了部分物源。

关键词: 铝土矿, 物源, 碎屑锆石年代学, 下二叠统, 黔北

Abstract: The problem about source materials of the sedimentary bauxite beds of Dazhuyuan Formation in Wuchuan-Zheng′ an-Daozhen area,northern Guizhou Province,is still controversial,for underlying strata of the bauxite beds transform from the Silurian Hanchiatien Formation to the Carboniferous Huanglong Formation in different areas.Detrital zircon chronological analysis of the sandstone of Hanchiatien Formation and bauxite beds shows the consistency of age spectrums and indicates the affinity of the basement strata in the Cathaysia Block.The result demonstrates that products from the weathering and laterization of the Hanchiatien Formation provide the materials for the mineralization of the bauxite beds. Meanwhile,the parallel unconformity between the bauxite beds and the Huanglong Formation and the secondary karstic breccia of the Huanglong Formation in the drilling core imply the contribution of the Huanglong Formation for the bauxite beds. Therefore,the Dazhuyuan bauxite beds has multiple sources, i.e. , materials from the Hanchiatien Formation may be the major source,while the Huanglong Formation provided not only the sedimentary place but also partial materials for mineralization during palaeokarst process.

Key words: bauxite, provenance, detrital zircon chronology, Lower Permian, northern Guizhou Province

中图分类号: 

• P611.2＋ 2A