中国铝土矿沉积中的碎屑锆石记录:对铝土矿物源模式与矿床分类的启示  

Detrital zircon records in bauxite deposits of China:Implication for the provenance model and ore deposits classification of bauxite

作　　者：余文超 杜远生 熊国林 周锦涛 庞大卫 邓旭升 翁申富 李沛刚[2,4] Yu Wen-Chao;Du Yuan-Sheng;Xiong Guo-Lin;Zhou Jin-Tao;Pang Da-Wei;Deng Xu-Sheng;Weng Shen-Fu;Li Pei-Gang(State Key Laboratory of Biogeology and Environmental Geology,School of Earth Sciences,China University of Geosciences(Wuhan),Wuhan 430074,China;Innovation Center of Ore Resources Exploration Technology in the Region of Bedrock,Ministry of Natural Resources of People's Republic of China,Guiyang 550081,China;Guizhou Geological Survey,Guiyang 550081,China;Geological Brigade 106,Bureau of Geology and Mineral Exploration and Development of Guizhou Province,Guizhou Zunyi 563000,China)

机构地区：[1]生物地质与环境地质国家重点实验室,中国地质大学(武汉)地球科学学院,湖北武汉430074 [2]自然资源部基岩区矿产资源勘查工程技术创新中心,贵州贵阳550081 [3]贵州省地质调查院,贵州贵阳550081 [4]贵州省地质矿产勘查开发局一〇六地质大队,贵州遵义563000

出　　处：《古地理学报》2020年第5期947-964,共18页Journal of Palaeogeography：Chinese Edition

基　　金：国家自然科学基金项目(编号: U1812402,41802116)资助。

摘　　要：通过收集、整理和分析来自中国20个铝土矿床/矿点的3439个碎屑锆石U-Pb年龄数据以及297个来自铝土矿沉积下伏碎屑岩基底的碎屑锆石U-Pb年龄数据,对近年来中国铝土矿床的碎屑锆石年代学研究进展进行了综述。对现代热带地区红土剖面中锆石矿物稳定性评估认为在强化学风化条件下锆石颗粒仍然能保持化学与物理的稳定性,因此锆石是铝土矿沉积中良好的物源指示物。对中国铝土矿沉积物源研究表明,即使是形成在碳酸盐岩基底上的铝土矿,其中仍有大量硅铝酸盐沉积物风化产物的加入。此前的铝土矿床分类体系,多依照基岩岩性与矿体形态结构特征进行分类,在使用时可能会造成分类的模糊性与不确定性。中国铝土矿沉积中广泛存在指示准原地及异地成因的碎屑锆石组分,使用原地/异地指标也无法进行有效区分。基于以上原因,建议在考虑铝土矿分类方案时,除考虑铝土矿的风化产物属性外,还应对其作为沉积物/沉积岩的属性加以考量,新的铝土矿床分类方案是当前铝土矿研究中亟待解决的问题。此外,铝土矿的碎屑锆石年代学研究虽然为铝土矿物源研究提供了重要约束,但仍然需要结合区域地质背景及地球化学研究来提供更全面的铝土矿物源信息。Based on 3439 detrital zircon U-Pb datapoints collected from the bauxite deposits of China and 297 detrital zircon U-Pb datapoints from underlying clastic rocks,this study reviews the recent progress in the detrital zircon U-Pb geochronology of bauxite deposits in China.Stability assessment of zircon grains in modern tropical weathering profiles proves the chemical and physical stability during the and intense weathering and bauxitization,which makes zircon become a good provenance indicator.Sedimentary provenance study of bauxite deposits in China indicates that even the bauxite deposit developed on the carbonate rocks,there was still considerable input of the weathering aluminosilicate materials.Previous classifications of bauxite deposit are mainly based on the lithology of basement rock and features of ore body,applications of these classifications will cause ambiguities and uncertainties.For widespread parautochthonous and allochthonous detrital zircon grains within Chinese bauxite deposits,parautochthonous and allochthonous criterion is invalid in classification of Chinese bauxite deposits.Here we suggest that the bauxite study requires a new classification of ore deposit,which should consider the weathering process of bauxite deposits as well as the position of bauxite deposit in the sedimentological framework.Although detrital zircon study provides important constrains for the provenance of bauxite deposits,combination of regional geological background and the geochemical characteristics are still essential for the comprehensive cognition of source materials.

关 键 词：锆石U-PB年代学 化学风化 铝土矿化 重矿物 

分 类 号：P618.45[天文地球—矿床学]