华北克拉通北缘柴胡栏子金矿富甲烷流体包裹体的发现及地质意义  

Discovery and geological significance of methane-rich fluid inclusions of Chaihulanzi gold deposit in the northern margin of the North China Craton

作　　者：张宇 唐名鹰 李永刚[4] 陆丽娜[5] 卢欣祥[6] 朱德全 何玉良[1,2] 彭翼 黄斐[1] 王炜晓[3] ZHANG Yu;TANG Mingying;LI Yonggang;LU Lina;LU Xinxiang;ZHU Dequan;HE Yuliang;PENG Yi;HUANG Fei;WANG Weixiao(Henan Institute of Geological Survey,Zhengzhou,Henan 450001,China;Henan Key Laboratory for Metal Mineral Ore-forming Geological Process and Utilization of Resource,Zhengzhou,Henan 450001,China;The 8th Institute of Geology and Mineral exploration of Shandong Province.Rizhao,Shandong 276826,China;State Key Laboratory of Lithos pheric Evolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;Institute of Disaster Prevention,Sanhe,Hebei 065201,China;Instituteof Land and Resources of Henan Province,Zhengzhou,Henan 450001,China)

机构地区：[1]河南省地质调查院,河南郑州450001 [2]河南省金属矿产成矿地质过程与资源利用重点实验室,河南郑州450001 [3]山东省第八地质矿产勘查院,山东日照276826 [4]中国科学院地质与地球物理研究所岩石圈演化国家重点实验室,北京100029 [5]防灾科技学院,河北三河065201 [6]河南省国土资源科学研究院,河南郑州450001

出　　处：《地质学报》2022年第4期1321-1339,共19页Acta Geologica Sinica

基　　金：国家自然科学基金项目(编号41802084);中国矿产地质志项目(编号DD20160346、DD20190379);河南省自然资源厅2019年省财政地质勘查项目(序号44)联合资助的成果。

摘　　要：柴胡栏子金矿位于华北克拉通北缘赤峰-朝阳金矿集区西段,是区内典型的石英脉型为主的金矿床,也是赤峰-朝阳地区首次发现的含大量单相甲烷包裹体群的金矿床。矿体呈脉状产于太古宙建平群大营子组下岩段含石墨绢云母片岩切层断裂中,金主要产出在蚀变含石墨绢云母片岩和石英脉中。根据野外观察和包裹体测温结果,将柴胡栏子金矿流体成矿过程划分为主成矿阶段和成矿晚阶段,分别为石英脉及蚀变岩型的矿石和无矿石英-方解石脉组合。流体包裹体岩相学和测温结果显示,主成矿阶段包裹体以水盐两相包裹体和单相纯甲烷包裹体为主,水盐包裹体均一到液相温度为135~377℃,平均256℃,盐度为3.06%~14.04%;甲烷包裹体均一温度为-107.6~-79℃,平均为-88.8℃。激光拉曼光谱分析显示,水盐包裹体气相成分主要以水为主,包含少量的CO_(2),极少量包裹体显示了明显的甲烷和水的峰值;甲烷包裹体中CH_(4)是唯一的成分,没有水峰的出现,少量包裹体中同时出现了CO_(2)和CH_(4)的的特征峰。流体包裹体群体亦显示主成矿阶段包裹体以水溶液包裹体为主,富甲烷包裹体明显发育,同时包裹体成分中含较多的CO_(2)和N_(2),与测温和激光拉曼光谱分析结果一致。成矿晚阶段方解石中仅发育水盐包裹体,均一温度为175~313℃,平均为250℃,盐度为1.57%~9.47%。H-O-S同位素分析显示,柴胡栏子金矿成矿流体主要来自岩浆水,成矿物质主要来自深源岩浆,成矿流体内的甲烷来自深源流体与含石墨围岩的交代反应。根据主成矿阶段水盐-甲烷包裹体共生组合的等容线相交图解,显示成矿流体的捕获温度为264~340℃,平均值为302℃,压力为102~154 MPa,平均值为128 MPa,pH-logfo_(2)图解显示成矿流体pH为4.25~5.05,logfo_(2)为-34.85~-34.54,金的络合物以Au(HS)^(2-)为主,金的溶解度为10×10^(-9)~46.6×10^(-9)。根据上述研究,认为�The Chaihulanzi gold deposit is located in the western section of the Chifeng-Chaoyang gold deposit on the northern margin of the NCC. It is a typical quartz vein type gold deposit, and is also the first gold deposit with a large number of single-phase methane inclusions found in the Chifeng-Chaoyang area. The ore body occurs in the fault, cutting across the quartz in the graphite-bearing sericite schist of the lower member of the Dayingzi Formation in the Archean Jianping Group. Gold occurs mainly in the altered graphite-bearing sericite schist and quartz veins. According to the results of field observation and inclusion temperature measurement, the fluid mineralization process of the Chaihulanzi gold deposit can be divided into the main mineralization period and the late mineralization stage, which are quartz vein and altered rock type ore and ore free quartz and calcite vein combination respectively. The results of fluid inclusion petrography and temperature measurement show that the inclusions in the main ore-forming stage are mainly water-salt two-phase inclusions and single-phase pure methane inclusions. The homogenization temperature of water-salt inclusions ranges from 135℃ to 377℃ with an average of 256℃, and the salinity ranges from 3.06% to 14.04%. The homogenization temperature of methane inclusions ranged from-107.6℃ to-79℃, with an average of-88.8℃. Laser Raman spectroscopy analysis showed that the gas phase composition of water-salt inclusions was mainly water, containing a small amount of CO_(2), and a very small amount of inclusions showed obvious peaks of methane and water. In the methane inclusions, CH_(4)is the only component, and there is no water peak. In a few inclusions, the characteristic peaks of CO_(2)and CH_(4)appear simultaneously. The fluid inclusion population also shows that the inclusions in the main ore-forming period are mainly aqueous solution inclusions, and the methane-rich inclusions are obviously developed. Meanwhile, the inclusions contain more CO_(2)and N_(2),

关 键 词：富甲烷流体包裹体 稳定同位素 柴胡栏子金矿 华北克拉通北缘 

分 类 号：P618.51[天文地球—矿床学]