河南祁雨沟金矿临界-超临界包裹体特征及成矿流体演化

Critical-Supercritical Fluid Inclusions Characteristics and OreForming Fluid Evolution of Qiyugou Gold Deposit,Henan Province

河南省祁雨沟金矿床位于华北地块南部熊耳地体东北缘，是我国典型的角砾岩型金矿。该矿床临界超临界流体包裹体的发现对研究成矿流体演化及成矿机制有重要意义。包裹体岩相学、显微测温以及激光拉曼显微探针（LRM ）研究显示，祁雨沟J4角砾岩筒中发育临界状态均一的包裹体富含CO2，这些包裹体出现在第Ⅰ、Ⅱ成矿阶段，并且在金品位最高的400460中段出现最为集中，对成矿有明显的指示作用。临界超临界流体来自富含挥发分的高氧化状态岩浆的出溶作用。流体演化先后经历了高氧化状态的岩浆流体体系→临界超临界流体体系→ H2 O NaCl和CO2 H2 O流体体系→低盐度的 H2 O NaCl流体体系→H2 O流体体系。临界-超临界流体体系在383．7～387．2℃发生了沸腾作用，沸腾作用可能是祁雨沟金矿J4岩筒中成矿物质沉淀的重要原因之一。

T he Qiyugou gold deposit in Henan Province , located in the northeastern Xionger metallogenetic district , southern margin of the North China craton , is a typical breccia pipe-type deposit .Discovering of critical-supercritical fluid inclusions is important to study ore-forming fluid＆amp;nbsp;evolution and metallogenic mechanism . Petrography , microthermometry and laser Raman microprobe （LRM） of fluid inclusions in the samples from the J4 breccia of Qiyugou deposit were analyzed .The research show s that the critical-supercritical fluid inclusions exist in stage Ⅱ （mainly ） and stage Ⅰ . Laser Raman spectroscopy analysis suggests this kind of fluid inclusions contain CO 2 . Critical-supercritical fluid inclusions are mostly included in the samples collected from the elevation of 400 460 m in the J4 breccia pipe ,where occurs a certain prospect with a higher gold grade ,thicker ore bodies and considerable reserves .Combined with existing fluid inclusion data ,a conclusion can be drawn that the supercritical fluid come from magmatic-hydrothermal transitional processes and the magma system was rich in volatile constituent and high oxygen fugacity .The evolution process of ore-forming fluid can be listed as magmatic-hydrothermal system→critical-supercritical fluid （CO2 H2 O NaCl system ）→vapor phase with low salinity （CO2 H2 O system） and liquid phase with high salinity （H2 O NaCl system） →low salinity （H2 O NaCl system）→ H2 O System .The homogenization temperatures of the boiling fluid inclusion changes from 383 .7 ℃ to 387 .2 ℃ .The fluid boiling played an important role in forming of the Qiyugou gold deposit .