河北省大北峪金矿床成矿流体特征及矿床成因

Genesis and ore-forming fluid characteristics of Dabeiyu Gold Deposit in Hebei Province

大北峪金矿床是太行山北段典型的金矿床。通过对大北峪金矿床的成矿流体特征进行研究,分析了矿床成因。矿体主要分布在新太古界阜平群与中元古界长城系高于庄组之间的拆离滑脱带和高于庄组白云岩的破碎蚀变带中,成矿划分为4个阶段:黄铁矿-石英阶段、石英-黄铁矿阶段、石英-多金属硫化物阶段和石英-碳酸盐阶段。成矿流体包裹体主要包括CO_(2)包裹体和气液两相包裹体,主成矿阶段成矿温度为262.8℃~346.4℃、盐度为8.6%~12.3%,密度为0.77~1.08 g/cm^(3)。成矿流体呈现中低温、中低盐度的CO_(2)-H_(2)O-NaCl体系和H_(2)O-NaCl体系特征。C、H、O同位素特征显示,成矿热液以岩浆水为主,混有大气降水。基于幔枝构造成矿理论,大北峪金矿床属于拆离滑脱带型金矿床。

Dabeiyu Gold Deposit is a typical gold deposit in the northern part of Taihang Mountains.The ore-forming fluid characteristics of Dabeiyu Gold Deposit are studied to analyze the genesis of the deposit.The ore body is mainly distributed in the glide-detachment faults between Neo-Archean Fuping Group and Meso-Proterozoic Changchangian Gaoyuzhuang Formation,and the Gaoyuzhuang Formation dolomite fracture alteration zone.The minera-lization process can be divided into 4 stages,namely pyrite-quartz,quartz-pyrite,quartz-polymetallic sulfide,and quartz-carbonate.The ore-forming fluid inclusions mainly include CO_(2)inclusion and gas-liquid inclusion.The tempera-ture during the main mineralization stage ranges from_(2)62.8℃to 346.4℃,the salinity ranges from 8.6%to 12.3%,and the density ranges from 0.77 g/cm^(3)to 1.08 g/cm^(3).The ore-forming fluid is characterized by medium-low tempera-ture and medium-low salinity CO_(2)-H_(2)O-NaCl and H_(2)O-NaCl systems.The C,H,and O isotope compositions show that ore-forming fluid mainly consists of magmatic water and mixes with atmospheric precipitation.Based on the metallogenic theory of mantle branch structure,Dabeiyu Gold Deposit belongs to the glide-detachment fault type gold deposit.