云南金宝山含矿岩体热液蚀变特征及其对Pt-Pd元素的富集作用  

Characteristics of hydrothermal alteration and its control to Pt-Pd enrichment of Jinbaoshan ore-bearing rock body in Yunnan

作　　者：欧阳菲[1,2] 同锐灵[3] 罗先熔[2] 曾南石[2] 

机构地区：[1]中国地质大学地球科学与资源学院,北京100083 [2]桂林理工大学地球科学学院,广西桂林541004 [3]广西区域地质调查研究院,广西桂林541003

出　　处：《桂林理工大学学报》2015年第4期686-693,共8页Journal of Guilin University of Technology

基　　金：国家科技支撑项目(2008BAB32B10-01B);广西地质工程中心重点实验室开放基金项目(桂科能07109011-K013)

摘　　要：金宝山含矿岩体是一个具有高铂钯背景值的超基性岩体。矿相学研究发现岩体中的热液蚀变作用具有多期、多类型叠加特征：首先经历了大规模水解形成面状分布的蛇纹岩,蚀变矿物组合为叶蛇纹石＋少量滑石;晚期蚀变沿裂隙分布,形成了复杂蚀变岩,局部叠加了绿泥石化、次闪石化和碳酸盐化组合。岩石化学分析发现,岩体中结合水含量高达10%,表明岩体经历了他变质作用,而不是目前大多数研究者认为的自变质作用。稀土元素分配特征表明,早期蛇纹石与蚀变橄榄岩具有同源一致性,明显区别于晚期以脉状产出的蛇纹石。铂钯矿物有两种存在形式：一种以类质同象形式分散于残留的早期造岩矿物中,另一种以独立矿物存在于晚期热液细脉中。微量元素分析表明：在残留造岩矿物的含矿岩体中铂钯的平均含量高,为0.4~0.5 g/t;而无残留造岩矿物的岩体中铂钯含量仅0.2 g/t左右。背散射电子分析表明,铂钯的独立矿物出现在岩体内的晚期热液细脉中。综合分析认为,热液蚀变作用对金宝山铂钯矿床的矿化富集起着重要作用,尤其是早期的大规模水解作用。The Jinbaoshan ore-bearing ultrabasic rock body is characterized by high platinum-palladium background value. Mineralographical studies show hydrothermal alteration in the rock body has poly-stage and polytype. It underwent the large-scale hydrolysis in the early stage,formed the planar serpentinite,included antigorite and minor talc. In the later stage,the hydrothermal alteration occurred along fracutres,formed the complex altered rock,overlaid the chloritization,uralitization and carbonatization. Petrochemistrical analysis shows content of bound water in the rock is as high as 10%,implying that the rock body has undergone chemical metamorphism instead of autometamorphism as most people think. REE distribution characteristic shows the serpentinite in the early stage has the same origin with alterative peridotite,and is obviously different from the vein serpentinite in the later stage. The Pt-Pd mineral has two forms： one is isomorphous which scattered in the residual metallic minerals,the other is independent mineral in late hydrothermal veinlets. Analysis result of trace elements shows the Pt-Pd content in the rock is about 0. 4- 0. 5 g / t,which is very high,while the content in the rock which doesn＇t remain metallic minerals is just 0. 2 g / t. Back scattered electron analysis shows independent mineral of Pt-Pd is found in the hydrothermal vain in the later stage. Comprehensive research proved the importance of hydrothermal alteration to mineralization of Jinbaoshan ore deposit,especially large-scale hydrolysis in the early stage.

关 键 词：热液蚀变 热液成矿 铂钯矿床 金宝山 云南 

分 类 号：P618.53[天文地球—矿床学]