安徽庐枞盆地泥河铁矿床与膏盐层的成因联系及矿床成矿模式  

The Metallogenic Model of Nihe Iron Deposit in Lu-Zong Basin and Genetic Relationship between Gypsum-Salt Layer and Deposit

作　　者：周涛发[1] 范裕[1] 袁峰[1] 吴明安[2] 赵文广[2] 钱兵[1] 马良[1] 王文财[1] 刘一男[1] Noel WHITE 

机构地区：[1]合肥工业大学资源与环境工程学院,合肥230009 [2]安徽省地质调查院,合肥230001

出　　处：《地质学报》2014年第4期562-573,共12页Acta Geologica Sinica

基　　金：国家"深部探测技术与实验研究专项(SinoProbe)"第三项目"深部矿产资源立体探测技术及实验研究"第四课题(编号SinoProbe-03-04);国家自然科学基金项目(编号41172084;41172086;41320104003);国家重点基础研究发展规划"973"项目(编号2012CB416802);中国地质调查局地质调查工作项目(编号1212011121115);安徽省国土资源科技项目(编号2013-k-1)资助成果

摘　　要：安徽庐枞盆地位于长江中下游断陷带内,地处扬子板块北缘,是长江中下游成矿带中重要的铁铜多金属成矿区和玢岩型铁矿的集中产地。庐枞盆地西北部勘探发现了大型泥河铁矿床,其硫铁矿和硬石膏矿床也达到了中大型规模,矿床中硬石膏在不同蚀变-矿化阶段均广泛发育,具有鲜明的成矿特色。深部勘探揭示庐枞盆地深部存在含石膏沉积地层(膏盐层),但目前膏盐层与成矿作用关系尚未引起研究重视。本文总结和分析了泥河铁矿床的地质地球化学特征,着重分析了膏盐层与铁矿床形成的关系,并在阐明成矿流体系统演化过程和成矿机理的基础上,提出泥河矿床的形成与三叠系膏盐层有着重要的成因关系,膏盐层是泥河铁矿床形成的重要地质条件之一。铁矿床及蚀变围岩中的大量硬石膏主要来自膏盐层;膏盐层为铁的成矿作用提供了大部分硫和矿化剂元素。在此基础上,建立了泥河铁矿床的两期成矿模式,即中晚三叠世含膏盐地层的沉积作用期(预备成矿期)和早白垩世的岩浆热液成矿期。The Lu-Zong Mesozoic volcanic Basin is located in the lower Yangtze River fault-depression zone, where is the north margin of the Yangtze Block. There are many magnetite-apitite deposits called Porphyrite iron deposits by the Chinese scientists.Nihe iron deposit located in the northwest part of Lu-Zong basin,it is a newly found large iron-sulfur-anhydrite deposit.Anhydrite is widely developed in almost each alteration-mineralization stage of Nihe deposit.Deep exploration work has revealed gypsum-bearing sedimentary rock deeper than 1800M below under the surface in the basement strata of Lu-Zong basin.However,the relationship between gypsum-salt layer and mineralization has not attracted much attention.Based on geology and geochemistry characteristics of Nihe iron deposit,the evolution process of ore-forming fluid system,the metallogenic mechanism and the characteristics of gypsum-salt layer have been discussed in this paper.The huge amount of anhydrite in iron ore bodies and altered wall rocks were mostly came from the underlying gypsum-salt layer indicated by sulfur isotope （δ34 S）and strontium isotope （87 Sr/86 Sr）i constrains.Geological and geochemical studies all show that Triassic gypsum-salt layer has played an important role in the formation of Nihe iron deposit.The gypsum-salt layer provided plenty of sulfur and mineralizing agent.Gypsum-salt layer is weak positions mechanically,which is prone to collapse and interlayer sliding between the layers when upward migration of magmatic hydrothermal invading and contacting with the gypsum-salt layer, this can provide channels for magmatic and hydrothermal emplacement and migration.On the basis of the above analysis,A two-stages of metallogenic model for Nihe deposits has been set up：the gypsum and salt sedimentation period in the middle-late Triassic （probationary period）and the magmatic hydrothermal mineralization period in early Cretaceous.

关 键 词：庐枞盆地 泥河铁矿床 膏盐层 成矿模式 玢岩铁矿 

分 类 号：P618.31[天文地球—矿床学]