中国北方盆地大规模铀成矿作用:地层篇  

The strata constraint on large scale sandstone- type uranium mineralization in Meso- Cenozoic basins, northern China

作　　者：程银行 金若时 Michel CUNEY V.A.PETROV 苗培森 CHENG Yinhang;JIN Ruoshi;Michel CUNEY;V.A.PETROV;MIAO Peisen(Tianjin Center,China Geological Survey(North China Center for Geoscience Innovation),Tianjin 300170,China;Key Laboratory of Uranium Geology,China Geological Survey,Tianjin 300170,China;Universitéde Lorraine,GéoRessources,CNRS,CREGU,Nancy F54500,France;Institute of Geology of Ore Deposits,Petrography,Mineralogy,and Geochemistry,Russian Academy of Sciences,Moscow 119017,Russia)

机构地区：[1]中国地质调查局天津地质调查中心(华北地质科技创新中心),天津300170 [2]中国地质调查局铀矿地质重点实验室,天津300170 [3]法国洛林大学资源学院,法国NancyF54500 [4]俄罗斯科学院矿床地质、岩石学、矿物学和地球化学研究所,俄罗斯Moscow119017

出　　处：《地质学报》2024年第7期1953-1976,共24页Acta Geologica Sinica

基　　金：国家重点研发计划项目(编号2023YFC2906700,2018YFC0604200);国家自然科学基金重点支持项目(编号92162212);自然资源部青年人才项目(自然资科技函[2022]129号);国家重点基础研究发展计划(973计划)(编号2015CB453000);国际地球科学计划(IGCP675);中国地质调查局地质调查工程、项目(编号0108,DD20230027,DD20221678,DD20190813等)联合资助的成果。

摘　　要：“红黑”耦合沉积建造是中国北方中—新生代盆地(简称北方盆地)砂岩型铀矿的重要控矿要素之一,在勘查实践中得到了广泛证实和应用,指导发现找矿靶区和矿产地300余处,在成矿理论方面取得重要进展。本文系统总结了北方产铀盆地的60万余米铀矿岩芯钻探成果,通过典型矿床赋矿层沉积学、地球化学等对比研究,系统分析了北方盆地侏罗系、白垩系、新近系等赋矿层形成的沉积环境、物质组成等,进一步明确了制约成矿流体运移、铀矿物沉淀的赋矿层条件。结果显示:①北方盆地自侏罗纪以来,发育了Ⅰ中侏罗世—晚侏罗世早期(Bathonian-Oxfordian)、Ⅱ早白垩世早期(Valanginian)、Ⅲ早白垩世晚期(Aptian)、Ⅳ晚白垩世早期(Cenomanian)、Ⅴ晚白垩世晚期—早古近纪(Campanian-Thanetian)、Ⅵ早新近纪(Aquitanian-Burdigalian)和Ⅶ晚新近纪(ZancleanPiacenzian)7期红层,与下伏富还原性组分的黑色层构成了典型的对偶沉积建造,为北方盆地大规模成矿奠定了赋矿层基础。②地球化学指标显示:红层中Fe^(2+)/Fe^(3+)比值介于0.29~1.47(n=78),黑层Fe^(2+)/Fe^(3+)比值介于0.57~53.96(n=223),赋矿层Fe^(2+)/Fe^(3+)比值介于1.00~26.45(n=52)。赋矿层、黑层Fe^(2+)/Fe^(3+)比值一般大于1,以发育黄铁矿、炭屑、油斑为特征,为相对较还原的环境。红层Fe^(2+)/Fe^(3+)比值一般小于1,以发育钙质结核为特征,为相对较强氧化的环境。③总有机碳含量显示红层为0~0.16%(n=107),含矿层为0.01%~2.65%(n=137),黑层为0.01%~2.66%(n=339),含矿层总有机碳含量略低于黑层,与铀矿的富集沉淀有密切关系。④砂岩型铀矿体呈“板状”或“楔状”产出于黑层顶部的灰色、灰绿色砂岩和细砂岩,甚至泥岩,红层为含氧含铀流体的运移通道,黑层为含氧含铀流体的富集沉淀的化学屏障。因此,北方盆地红层和黑层对偶沉积、旋回充填是大规模铀成矿必要的地层�The“red-black”coupling sedimentary architecture is one of the most important ore-controlling feature for sandstone-type uranium deposits in the Middle and Cenozoic basins of northern China(hereafter referred to as the Northern basins).This feature has been extensively validated and applied in exploration strategies,leading to the discovery of over 300 prospecting targets and orefields.Concurrently,metallogenic theories have undergone substantial advancements,resulting in a more comprehensive understanding of the processes governing ore formation.This publication summarizes findings from over 600 km of boreholes in the Northern basins.Comparative analyses of sedimentology and geochemistry in typical deposits provide insights into the depositional conditions and material compositions of Cenozoic,Cretaceous,and Jurassic reservoirs.This analysis further reveals the reservoir conditions controlling metallogenic fluid flow and uranium mineral precipitation.The findings demonstrate that the Northern basins have developed seven distinct sets of red beds since the Jurassic:(1)Middle Jurassic-Early Late Jurassic(Bathonian-Oxfordian),(2)Early Cretaceous(Valanginian),(3)Late Early Cretaceous(Aptian),(4)Early Late Cretaceous(Cenomanian),(5)Late Late Cretaceous-Early Paleocene(Campanian-Thanetian),(6)Early Cenozoic(Aquitanian-Burdigalian),and(7)Late Cenozoic(Zanclean-Piacenzian).The red beds and the underlying black organic-rich strata form the foundational reservoir architecture for large-scale uranium mineralization in the Northern basins.Geochemical indicators show distinct Fe^(2+)/Fe^(3+)ratios:red strata(0.29~1.47,n=78),black strata(0.57~53.96,n=223),and orebodies(1.00~26.45,n=52).Both orebodies and black strata,typically characterized by Fe^(2+)/Fe^(3+)ratios greater than 1,exhibit features indicative of reducing environment,including the growth of pyrite,carbon debris,and oil spots.Conversely,red strata,with Fe^(2+)/Fe^(3+)ratios generally less than 1,are characterized by calcareous nodules,signifying an oxidizing e

关 键 词：北方中—新生代盆地 砂岩型铀矿 大规模成矿 沉积环境 赋矿层 

分 类 号：P619.14[天文地球—矿床学]