哈播富碱侵入岩体接触带金矿床成矿流体演化特征

The evolution characteristics of metallogenic fluids for Au deposits in the contact of the Habo alkaline intrusion

哈播富碱侵入岩体位于哀牢山-红河新生富碱侵入带的南段西侧,该岩体由4个单元组成,分别是坪山单元(EP)、三道班单元(ES)、阿树单元(EA)及哈播南山单元(EH)。锆石U-Pb年代学研究表明:坪山单元成岩年龄约为36 Ma;三道班单元成岩年龄约为35 Ma;阿树单元成岩年龄约为37 Ma;哈播南山单元成岩年龄约为33 Ma。围绕该岩体与围岩接触带分布着一系列中小型金矿床,分别是哈播金矿床、哈埂金矿床及沙普金矿床,这些金矿床与哈播富碱侵入岩体有着密切的时空联系。岩体及矿床微量稀土元素研究表明:1)哈播富碱侵入体与金沙江-哀牢山富碱斑岩带北端的玉龙、多霞松多斑岩有着非常相似的蛛网及稀土元素配分图,表明二者具有相同的成岩背景及物质来源;2)哈播金矿床、哈埂金矿床、沙普金矿床及哈播富碱侵入岩体有着相同的物质来源,其源区具有壳幔混合特征;3)各矿床成矿流体富Cl^-,而F^-含量则较低;成矿流体富集亲硫元素Cu、Zn、Cd、Pb及铁族元素Co、Ni;4)哈播金矿床、哈埂金矿床及沙普金矿床总体成矿物理化学条件为还原环境,但是该区成矿热液体系较复杂,这种复杂的成矿热液体系与哈播富碱侵入岩体脉动式侵入造成的热叠加效应有关。

The Habo alkaline intrusion, located in the southern part of the Ailaoshan-Red River Cenozoic alkaline intrusion belt, consists of Pinshan(EP), Sandaoban(ES), Ashu(EA), and Habonanshan(EH) four units. The zircon U-Pd dating results show that these units have weighted mean 206 Pb/238 U ages of 36 Ma(EP), 35 Ma(ES), 37 Ma(EA), and 33 Ma(EH), respectively. A series of small-to medium-sized Au deposits, such as the Habo, Hageng, and Shapu, are distributed around the Habo intrusion, with closely temporal and spatial relationships. The results of trace and REE elements of intrusive rock and deposits show that the Habo alkaline intrusion has very similar trace element spidergrams and REE patterns to those of the Yulong and Duoxiasongduo porphyry bodies, which are located in northern part of the Jinshajiang-Ailaoshan alkaline-rich porphyry belt, indicating that they could have almost same diagenetic tectonic setting and source materials. The Habo, Hageng and Shapu Au deposits share the same source materials, which are characterized with the mixing of crust and mantle, with the Habo alkaline intrusion. The ore-forming fluids of these deposits are characterized with Cl^--rich and F^--poor, enriched thiophilic elements(Cu, Zn, Cd, Pb) and iron group elements(Co, Ni). The physicochemical conditions of mineralization of the Habo, Hageng and Shapu Au deposits are generally reduced environment. The ore-forming hydrothermal systems in the ore field, however, are relatively complicated. This complicated ore-forming hydrothermal system could be related to the hydrothermal superimposition caused by the pulsing emplacement mechanism of the Habo intrusion.