四川盆地北部砂岩型铀矿成矿作用与成矿模式及对找矿方向的启示  

Mineralization and Metallogenic Model of Sandstone-type Uranium Deposits in Northern Sichuan Basin and Its Implications for Uranium Prospecting

作　　者：丁波[1] 贺锋[1] 刘红旭[1] 邱林飞[1] 肖珂相 王战永 杨嘉宝 DING Bo;HE Feng;LIU Hongxu;QIU Linfei;XIAO Kexiang;WANG Zhanyong;YANG Jiabao(CNNC Key Laboratory of Uranium Resources Exploration and Evaluation Technology,Beijing Research Institute of Uranium Geology,Beijing 100029,China;Research Institute No.280,CNNC,Guanghan,Sichuan 618300,China)

机构地区：[1]核工业北京地质研究院中核集团铀资源勘查与评价技术重点实验室,北京100029 [2]核工业二八○研究所,四川广汉618300

出　　处：《铀矿地质》2021年第6期1027-1036,共10页Uranium Geology

基　　金：中国核工业地质局项目“四川盆地砂岩型铀矿资源潜力分析与战略选区”(编号:地D2004)资助。

摘　　要：四川盆地北部是中国重要的砂岩型铀矿成矿带之一。虽然大量学者对已探明铀矿成矿作用等方面开展了研究,但砂岩型铀矿成因至今仍存在较大的分歧。此外,现阶段对与铀成矿有关的热液性质与来源、如何造成铀的叠加富集等方面研究不足,尤其是对红色含铀方解石脉形成机制及红色铀矿石中铀矿物与赤铁矿、方解石的内在成因关系仍有待深化认识。因此,文章全面收集前人研究资料,系统总结了川北砂岩型铀矿化特征与主要控矿因素,在沉积成岩富集成矿的基础上,提出与铀成矿有关的热液为富CO_(2)的含烃盆地热卤水,当其通过断裂及不整合面运移时,随着热液pH值上升及Eh值的增高,容易造成CaCO_(3)、Fe(OH)_(3)先后沉淀与铀酰离子卸载,形成含铀红色方解石脉与红化铀矿石,进而建立了川北砂岩型铀矿沉积成岩铀重新分配与热液叠加改造两阶段成矿模式,指出干旱-半干旱背景下的局部相对潮湿环境下的河道沉积建造与断裂构造叠合位置是富矿形成的有利部位,为该区砂岩型铀矿找矿提供方向。The northern Sichuan Basin is one of the important sandstone-type uranium metallogenic belts in China.Although a large number of scholars have carried out research on the proven uranium mineralization,there are still great differences on the genesis of sandstone-type uranium deposits.In addition,the research on the properties and sources of hydrothermal fluids related to uranium mineralization,and mechanism of superimposed enrichment uranium are insufficient,especially the formation mechanism of red uranium bearing calcite vein and the internal genetic relationship between uranium minerals and hematite,calcite in red uranium ore still need to be understood.Therefore,this paper comprehensively collected the previous research data,systematically summarized the characteristics and main ore controlling factors of sandstone-type uranium mineralization in northern Sichuan.On the basis of uranium enrichment and mineralization in sedimentary diagenesis,it was proposed that the hydrothermal fluid related to uranium mineralization was CO_(2) rich hydrocarbon-bearing basin brine.When it migrated through faults and unconformities,with the increase of pH and Eh,it is easy to caused the precipitation of CaCO_(3) and Fe(OH)_(3) successively and unloading of uranyl ions,forming uranium-bearing red calcite vein and red uranium ore.Furthermore,it was proposed that the sandstone-type uranium deposit in northern Sichuan has experienced two stages of mineralization,i.e.uranium redistribution in sedimentary diagenesis and hydrothermal superimposition.It was pointed out that the superimposed position of channel sedimentary formation in the local relatively humid climate under the arid and semi-arid background and fault structure was the favorable position for the formation of rich ores,which provided the direction for the next prospecting of sandstone-type uranium deposits in this area.

关 键 词：砂岩型铀矿 热液改造 铀成矿作用 找矿方向 四川盆地 

分 类 号：P619.14[天文地球—矿床学]