首页|夹皮沟成矿带小北沟金矿床成矿流体特征及其地质意义

夹皮沟成矿带小北沟金矿床成矿流体特征及其地质意义

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小北沟金矿床地处夹皮沟成矿带中部,为石英脉-蚀变岩型金矿床.矿区赋矿围岩主要为高角闪岩-麻粒岩相斜长角闪岩,含金石英脉呈小而不连续的平行细脉或透镜体状产于NW向叠加于早期韧性剪切带之上的次级脆性剪切裂隙之中,其上、下盘旁侧及尖灭处发育少量低品位蚀变岩型(蚀变糜棱岩、片糜岩)矿体.主成矿阶段流体包裹体研究表明,矿石中石英主要发育CO2、富CO2、含CO2及气液两相四种类型原生流体包裹体,测温结果显示包裹体均一温度为226.8～362.5 ℃,盐度(w(NaCl))为3.57％～11.95％,密度为0.65～0.91 g/cm3;成矿流体总体属中低温、中低盐度和低密度的富CO2的CO2-H2O-NaCl体系,成矿压力为70～206 MPa,成矿深度约为9.8 km.包裹体O同位素δ18OV-SMOW值为10.8‰～11.3‰,H 同位素 δDV-SMOW值为-102.8‰～-96.7‰,C 同位素 δ13CV-PDB值为-20.6‰～-8.3‰,反映主成矿阶段成矿流体来源具幔源属性.矿石中CO2和富CO2包裹体CO2相均一温度为-24.7～26.6 ℃,明显低于邻近其他矿床(如三道岔金矿床为21.9～29.7 ℃,二道沟金矿床为23.8～30.9 ℃等),暗示其成矿深度较深.小北沟金矿床的地质、流体包裹体和H-O-C同位素特征共同揭示该矿床属于中温热液脉型金矿床,处于深大断裂的脆性区构造层次向韧脆性区构造层次过渡部位,深部仍应有一定的进一步找矿前景,但矿石类型可能由石英脉型转为构造蚀变岩型或蚀变糜棱岩型.
Characteristics and Geological Significance of Ore-Forming Fluids in Xiaobeigou Gold Deposit of the Jiapigou Metallogenic Belt
The Xiaobeigou gold deposit is located in the middle of Jiapigou metallogenic belt and is a quartz vein-altered rock type gold deposit.The ore-bearing surrounding rock of the mining area is mainly high amphibolite and granulite facies plagioclase amphibolit.The gold-bearing quartz veins are small,discontinuous parallel veins or lenticular bodies found within secondary brittle shear fractures superimposed on an early ductile shear zone trending NW.There are also some low-grade altered rock type orebodies(altered mylonite and gylite)developed on the sides of the upper and lower plates,and at the apex.The study of fluid inclusions from the main ore-forming stage shows four types of primary fluid inclusions:CO2,CO2-rich,CO2-containing and gas-liquid two phases.The homogenization temperatures range from 226.8 to 362.5 ℃,with salinity w(NaCl)between 3.57％and 11.95％,and density of 0.65 to 0.91 g/cm3.The ore-forming fluid generally belongs to the CO2-H2O-NaCl system,characterized by low temperature,low salinity and low density.The ore-forming pressure ranges from 70 to 206 MPa,corresponding to a depth of about 9.8 km.The δ18OV-SMOW composition of the O isotope ranges from 10.8‰ to 11.3‰,while 8DV-SMOW value of the H isotope show values of-102.8‰ to-96.7‰,and the 813CV-PDB values of the C isotope are between-20.6‰ and-8.3‰,indicating that the ore-forming fluid source of the main ore-forming stage is of mantle origin.The homogenization temperature of CO2 and CO2-rich inclusions are notably lower at-24.7 to 26.6 ℃ compared to other nearby deposits(such as Sandaocha gold deposit of 21.9 to 29.7 ℃,Erdaogou gold deposit of 23.8 to 30.9 ℃,etc.),suggesting a deeper mineralization.The geological,fluid inclusions and H-O-C isotopic characteristics of Xiaobeigou gold deposit indicate it is a medium-temperature hydrothermal vein type gold deposit,transitioning from the brittle zone to the deep ductile-brittle zone.There remains potential for further deep exploration,though the ore type may change from quartz vein type to tectonic-altered rock type or tectonic-altered mylonite type.

ore-forming fluidfluid inclusionsH-O-C isotopesmesothermal vein gold depositXiaobeigou gold depositJiapigou metallogenic belt

李斌、臧兴运、王永胜、刘振宇、苏斌、闫冬

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山东省地质矿产勘查开发局第六地质大队/深部金矿探测大数据应用开发山东省工程研究中心/自然资源部深部金矿勘查开采技术创新中心,山东 威海 264209

吉林省地质调查院,长春 130102

成矿流体 流体包裹体 H-O-C同位素 中温热液脉型金矿 小北沟金矿床 夹皮沟成矿带

深部金矿探测大数据应用开发山东省工程研究中心项目自然资源部深部金矿勘查开采技术创新中心项目中国地质调查局项目

SDK202219LDKF-2023BZX-25DD20190379

2024

10.13278/j.cnki.jjuese.20230243

吉林大学学报(地球科学版)
吉林大学

吉林大学学报(地球科学版)

CSTPCD北大核心
影响因子：1.062
ISSN：1671-5888
年,卷(期)：2024.54(5)