| 宁夏卫宁北山金场子金矿床流体来源及矿床成因:来自流体包裹体和C?H?O同位素证据 |
| |
| 引用本文： | 海连富,刘安璐,陶瑞,白金鹤,宋扬.宁夏卫宁北山金场子金矿床流体来源及矿床成因:来自流体包裹体和C?H?O同位素证据[J].地球科学,2021,46(12):4274-4290. |
| |
| 作者姓名： | 海连富 刘安璐 陶瑞 白金鹤 宋扬 |
| |
| 作者单位： | 中国地质大学资源学院,湖北武汉 430074;固体矿产勘查国家级实验教学示范中心,湖北武汉 430074;宁夏回族自治区矿产地质调查院,宁夏银川 750021;中国地质大学逸夫博物馆,湖北武汉 430074;宁夏回族自治区矿产地质调查院,宁夏银川 750021 |
| |
| 基金项目： | 宁夏回族自治区重点研发计划重大（重点）项目2018BFG02013宁夏优秀人才支持计划项目JTGC2019023宁夏自然科学基金项目2021AAC03447 |
| |
| 摘 要： | 卫宁北山地区是宁夏境内最有望实现找矿突破的多金属矿成矿区之一，已发现众多Au、Ag、Cu、Pb、Zn、Fe、Co等矿点或矿化点.金场子金矿是该地区已发现的最大的金矿床，矿体主要赋存在前黑山组及中宁组内的层间断裂破碎带中，呈东西向带状分布，产状与地层近乎一致.区域上除少量闪长玢岩脉出露外，岩浆岩不发育.为了探讨金场子金矿成矿流体性质、来源和矿床成因，对研究区流体包裹体和C-H-O同位素进行了研究.金场子金矿床成矿热液期可划分为4个成矿阶段，从早到晚分别是绢云母-黄铁矿-石英阶段（Ⅰ）、黄铁矿-重晶石-石英阶段（Ⅱ）、多金属硫化物-碳酸盐-石英阶段（Ⅲ）和黄铁矿-碳酸盐阶段（Ⅳ），其中Ⅲ阶段为主成矿阶段.不同成矿阶段的流体包裹体有4种类型，分别是水溶液包裹体、纯CO2包裹体、CO2-H2O包裹体和含子晶多相包裹体.显微测温结果显示，成矿流体的完全均一温度介于171~396 ℃，主要集中于180~270 ℃，盐度介于1.30%~10.99% NaCl equiv，密度为0.24~0.78 g/cm3，为中低温、低盐度、低密度的CO2-H2O-NaCl体系，含有少量N2.热液期石英的δD值为-66.0‰~-32.0‰，δ18OV-SMOW值为+19.7‰~+22.6‰，指示成矿流体为变质流体.C同位素显示，晚阶段（Ⅳ）方解石和菱铁矿的δ13C介于-2.540‰~-0.736‰，表明成矿流体中的C具有混合来源的特点，奥陶系-石炭系陆源碎屑岩和碳酸盐岩的变质脱水作用形成的流体可能是金成矿流体的主要来源.成矿过程中流体发生了明显的不混溶现象，是造成金沉淀的重要因素.矿床成因类型属造山型金矿.
|
| 关 键 词： | 稳定同位素 成矿流体来源 矿床成因 流体包裹体 金场子金矿床 卫宁北山 |
| 收稿时间： | 2021-04-03 |
Source of Fluid and Genesis of Jinchangzi Gold Deposit in Weiningbeishan,Ningxia: Evidence from Fluid Inclusions and C-H-O Isotopes |
| |
| Abstract: | The Weiningbeishan area is the most promising polymetallic ore target area in Ningxia, where numerous Au, Ag, Cu, Pb, Zn, Fe, Co, and other ore occurrences have been found. The Jinchangzi gold deposit is the largest gold deposit found in the area, and the ore bodies are mainly hosted in the intra-layer fault fractures, with an east-west distribution and near-uniform with the bedding. Magmatism is weak in this district, with several diorite porphyrite having been identified in exposures adjacent to the gold veins. In order to explore the nature, source and genesis of the ore-forming fluid of the Jinchangzi gold deposit, the fluid inclusions and C-H-O isotopes in the study area were studied. The ore-forming hydrothermal period of the deposit can be divided into 4 metallogenic stages, from early to late, they are sericite-pyrite-quartz stage (Ⅰ), pyrite-barite-quartz stage (Ⅱ), polymetallic sulfide-carbonate-quartz stage (Ⅲ) and pyrite-carbonatite stage (Ⅳ), of which stage Ⅲ is the main metallogenic stage. There are four types of fluid inclusions in the mineralization stage, which are aqueous solution inclusions, pure CO2 inclusions, CO2-H2O inclusions and multiphase inclusions containing daughter crystals. The completely homogenous temperature of the ore-forming fluids is between 171-396℃, the salinity is between 1.30%-10.99% NaCl equiv, and the density is 0.24-0.78 g/cm3, which are CO2-H2O-NaCl systems with medium-low temperature, low salinity, low density, CO2 rich, and a small amount of N2. The δD value of hydrothermal quartz is -66.0‰ to -32.0‰, and the δ18OV-SMOW value is (+19.7‰)-(+22.6‰), indicating that the ore-forming fluid is metamorphic and the magmatism is not obvious. The C isotope shows that the δ13C of calcite and siderite in the late stage (stage Ⅳ) is between -2.540‰ and -0.736‰, indicating that C in the ore-forming fluid has the characteristics of mixed sources. The fluids formed by the metamorphic dehydration of Ordovician-Carboniferous terrigenous clastic rocks and carbonate rocks may be the main source of gold ore-forming fluids. During the ore-forming process, the fluids had an obvious immiscibility phenomenon, which was an important factor causing gold precipitation. The genetic type of the deposit is an orogenic gold deposit. |
| |
| Keywords: | |
| 本文献已被 万方数据 等数据库收录！ |
| 点击此处可从《地球科学》浏览原始摘要信息 |
|
点击此处可从《地球科学》下载全文 |
|
