(1. 中南大学地球科学与信息物理学院有色金属成矿预测教育部重点实验室,长沙 410083;
2. 灵丘县梨园金矿有限责任公司,灵丘 034403)
摘 要: 山西梨园金矿位于太行山构造-岩浆-多金属成矿带上,矿体赋存于北北东向的构造带中,矿床热液作用包括石英脉阶段(A)、石英-黄铁矿阶段(B)、石英-多金属硫化物阶段(C)和石英-碳酸盐阶段(D)。B、C、D阶段的石英中发育3类包裹体:气液两相包裹体(Ⅰ型)、水溶液-CO2包裹体(Ⅱ型)以及纯CO2包裹体(III型)。B阶段发育Ⅰ型包裹体、部分Ⅱ型及Ⅲ型包裹体,均一温度集中于230~350℃,盐度为1.82%~12.63%;C阶段发育Ⅰ型包裹体,Ⅱ型及Ⅲ型包裹体明显增多,均一温度集中于200~330℃,盐度为1.82%~9.71%;D阶段主要发育Ⅰ型包裹体,均一温度集中于140~170 ℃,盐度为1.16%~9.58%。包裹体气相成分含有较高密度的CO2和CO、N2、H2、CH4等,液相成分主要为Ca2+、Na+、K+、SO42-、Cl-、F-。估算成矿压力为68~114 MPa,对应的捕获温度为200~430℃,估算最大成矿深度为4.3km。梨园金矿成矿流体为低盐度、中低温、富CO2的Ca2+(Na+、K+)-SO42-(Cl-、F-)-H2O-CO2体系,可能为后期岩浆热液流体。矿床形成于陆内造山环境,为受断裂破碎带控制的岩浆热液蚀变岩型金矿。
关键字: 流体包裹体;成矿流体;包裹体成分;矿床成因;梨园金矿
(1. Key Laboratory of Metallogenic Prediction of Nonferrous Metals, Ministry of Education,
School of Geosciences and Info-Physics, Central South University, Changsha 410083, China;
2. Liyuan Gold Deposit Limited Liability Company, Lingqiu 034403, China)
Abstract:Liyuan Gold Deposit is located at the Taihang Mountain tectonic-magma-polymetallic metallogenic belt. Ore bodies mainly occur in the NNE-trending structural zone. The hydrothermal process can be divided into four stages, namely, A stage (quartz vein stage), B stage (quartz-pyrite stage), C stage (quartz-polymetallic sulfide stage) and D stage (quartz-carbonate stage). Three types of fluid inclusions are developed in B, C and D stages: aqueous inclusion (type Ⅰ), CO2-aqueous inclusion (type Ⅱ) and pure CO2 inclusion (type Ⅲ). All three types of inclusions, mainly type I inclusions present in stage B, with homogenization temperatures ranging in 230-350 ℃, and salinities ranging from 1.82% to 12.63%. In addition to development of type Ⅰ inclusions, type Ⅱ and Ⅲ inclusions increase significantly in stage C, with homogenization temperatures ranging from 200 ℃ to 330 ℃, salinities ranging in 1.82%-9.71%. Type Ⅰ inclusions relatively develop in stage D, with homogenization temperatures concentrating in 140-170 ℃, and salinities ranging from 1.16% to 9.58%. High density of CO2 and CH4, H2 and N2 are found as gascompositions in the inclusions. Liquid phase of fluid is mainly composed of Ca2+, Na+, K+, SO42-, Cl-, F-. The calculated metallogenic pressures are in the range of 68-114 MPa, corresponding to capture temperature of 200-430 ℃, and the maximum estimated mineralization depth is 4.3km. To sum up, the mineralization fluid of Liyuan Gold Deposit may be late magmatic hydrothermal fluid, belongs to low salinity, medium-low temperature,CO2-rich Ca2+(Na+, K+)-SO42-(Cl-, F-)-H2O-CO2 system. Liyuan Gold Deposit formed in intracontinental orogeny belongs to magmatic hydrothermal altered rock type gold deposit controlled by fracture zone.
Key words: fluid inclusion; mineralization fluid; fluid inclusion composition; ore genesis; Liyuan Gold Deposit