四川会理红泥坡铜矿床流体包裹体特征

Fluid inclusion Characteristics of the HongnipoCopper Deposit in the HuiliCounty,Sichuan Province

四川会理红泥坡矿床位于扬子西南缘的拉拉矿田内,是近年来新发现的大型矿床,矿体主要赋存于古元古河口群的地层中。矿床研究程度较低,成矿流体来源及性质等尚不清楚。因此,本文通过岩相学、矿相学以及流体包裹体的研究对红泥坡铜矿床成矿流体的来源及性质进行探讨。根据脉体间的穿插关系和矿石组构特征将其矿化作用划分火山-沉积期和热液成矿期。火山-沉积期不发育流体包裹体,热液成矿期石英及方解石中主要发育气液两相包裹体和含盐类子晶包裹体,少见CO_(2)-H_(2)O三相包裹体,纯液相CO_(2)包裹体,纯气相水包裹体、纯液相水包裹体。含子晶包裹体均一温度范围主要介于112.8~323.6°C之间,盐度范围为32.2%~54.3%NaCl_(eq);气液两相包裹体均一温度范围主要介于120~230°C之间,盐度范围为5.2%~36.8%NaCl_(eq)。据析红泥坡铜矿床中极大可能是因为流体混溶作用导致主成矿阶段铜矿质沉淀,即在流体运移过程中混入低温、低盐度流体导致流体物理、化学条件发生改变而导致成矿元素沉淀。

In this paper,the origin and nature of ore-forming fluids are discussed in Hongnipo copper deposit through the study of fluid inclusion petrography and microthermometry.Based on the interpenetration relationship of the veins and the characteristics of ore structure,the metallogenetic process of Hongnipocopper deposit can be divided into volcano-sedimentary stage and hydrothermal mineralization stage.The fluid inclusions are not developed in volcano-sedimentary stage,while the fluid inclusions in the hydrothermal minerals from the copper mineralization stage include:biphase aqueous inclusions,multiphase aqueous inclusions with crystals,monophase liquid CO_(2) and H_(2)O inclusions,monophase vapor H_(2)O inclusions,and minortriphase CO_(2)-H_(2)Oinclusions.The homogenization temperature of aqueous inclusions with crystalsrange from 112.8 to 323.6 ℃,with a high salinitiesof 32.2 to 54.3wt%NaCl_(eq).The homogenization temperature of biphase aqueous inclusionsrange from 120 to 230 ℃,corresponding to a wide range of salinitiesof5.2 to 36.8wt%NaCl_(eq).It is concluded thatfluid mixing is the critical mechanism for the copper precipitationin the main mineralization stage.In the process of fluid migration,low temperature and low salinity fluids were mixed,which resulted in the change of fluid physical and chemical conditions and resulted in the precipitation of ore-forming elements.