河南庄金矿床成矿流体特征及矿床成因

河南庄金矿位于秦岭褶皱系北缘东端,为一产于变质岩层间破碎带中的蚀变岩、石英脉复合型金矿床。流体包裹体研究表明,包裹体类型主要为纯CO2包裹体和CO2+H2O包裹体,其中CO2+H2O包裹体均一温度变化为241～398℃,均一压力为100～250MPa,盐度为7.1%～13.6%NaCl,暗示成矿流体应为中低压力环境下的富CO2的中低盐度中高温流体。矿石中氢、氧和硫同位素组成含量分别为-92.2‰～-79.0‰、9.3‰～11.0‰和8.5‰～11.6‰,具有岩浆热液的特征,但可能与围岩发生了一定的交换。总之,河南庄金矿为岩浆期后热液矿床,CO2是金搬运和沉淀的主要控制因素。

Ore-forming fluid characteristics and ore genesis in Henanzhuang Gold Deposit

Henanzhuang Gold Deposit,a coexistent quartz-vein type and altered-rock type gold deposit,is located at the eastern part of the northern Qinling Orogenic Belt.Researches on fluid inclusions of quartz show that two types of inclusions can be identified,including pure CO2 inclusion and H2O+CO2 inclusion.The H2O+CO2 inclusion(241~398℃ homogenization temperature,100~250 MPa homogenization pressure,and 7.1%~13.6% NaCl salinities) indicates that ore-forming fluid was in the environment of moderate-high temperature,low-moderate pressure and low salinity.The contents of hydrogen,oxygen and sulfur stable isotopes are-92.2‰~-79.0‰,9.3‰~11.0‰ and 8.5‰~11.6‰ respectively,which are characterized by magmatic hydrotherm features coupled with wall-rock contamination.In conclusion,Henanzhuang Gold Deposit is related to magmatic fluids,and CO2 is significant for aurum transportation and deposition.