滇西北红牛—红山铜钼矿床元素迁移趋势及蚀变分带特征

Element Migration Trends and Alteration Zoning Characteristics of Hongniu-Hongshan Copper-Moly bdenum Deposit in Northwestern Y unnan

通过对红牛-红山铜钼矿床主要矿物岩(矿)石(矽卡岩、大理岩、角岩、斑岩等)进行主微量、稀土元素地球化学特征分析,研究其成矿阶段元素富集迁移规律,同时对该区蚀变分带特征进行厘定,为该区下一步找矿提供理论依据.发现该区共有三种成矿类型((1)大理岩→矽卡岩化大理岩→矽卡岩;(2)角岩→矽卡岩化角岩→矽卡岩;(3)斑岩→矽卡岩→矽卡岩矿石),其中(3)类型为矿区最主要的蚀变矿化类型,最主要的成矿元素Cu、Mo在该阶段中大量富集成矿,不同的是Cu为全阶段大量富集迁入,而Mo主要在斑岩→矽卡岩阶段大量富集,而在矽卡岩→矽卡岩矿石过程迁入趋势明显减弱.将三种蚀变矿化类型视为一个成矿系统,计算其元素质量迁移率,发现虽然都是主要的蚀变矿化类型,但是(3)类型的质量迁移率远大于其他两种,(1)的大理岩矽卡岩化阶段质量迁移率仅为-0.64%,原因是在大理岩矽卡岩化热液蚀变过程中CaO、MgO为矽卡岩化过程提供物质来源,他们的大量迁出为形成矽卡岩创造了环境条件,总体仍呈迁出状态.同时该区具有明显的垂直蚀变分带特征,大理岩、角岩、矽卡岩三者关系密切.

By analyzing the geochemical characteristics of major,trace,and rare earth elements of the primary mineral rocks(ores)(skarn,marble,hornfels,porphyry,etc.)in the Hongniu-Hongshan copper-molybdenum deposit,we study the law of elemental enichment and migration during the mineralzation stage and determine the characterstics of alteration zoning in the area.This research provides a theoretical basis for further prospecting in the region.We find that there are three types of mineralization in this area(①marble-skarn-marble-skarn,②hornfels→skarn-hornfels→skam,③porphyry→skarn→skarn ore),among which type③is the primary mineralization type in the mining area.The main ore-forming elements Cu and Mo are enriched and mineralized in this stage.The difference is that Cu is enriched and migrates in large quantities throughout the stage,while Mo is primarily enriched in the porphyry-+skarn stage,with the migration trend of skarn-skarn ore noticeably weakened.The three metallogenic types are considered as a metallogenic system,and their elemen-tal mass mobility is calculated.We find that although all three are major metal logenic types,the mass mobility of type③is far greater than the other two.The mass mobility of the marble-skarn stage of type①is only-0.64%,as CaO and MgO provide material sources for the skarn process during the hydrothermal alteration of marble-skarn.Their massive emigration creates environmental conditions for the formation of skarn,which is still in the state of emigration.Simultaneously,the area displays distinct characteristics of vertical alteration zoning.Marbles,hornfels,and skarns are closely related.