| 杨永胜.低硫化型与高硫化型浅成低温热液金矿中蚀变特征与成矿关系的对比研究[J].地质与勘探,2015,51(4):655-669 |
| 低硫化型与高硫化型浅成低温热液金矿中蚀变特征与成矿关系的对比研究 |
| Comparison of hydrothermal alteration characteristics of low sulfidation and high sulfidation epithermal gold deposits and their relation with mineralization |
| 投稿时间：2014-12-04 修订日期：2015-03-22 |
| DOI： |
| 中文关键词: 浅成低温热液金矿 低硫化型 高硫化型 热液蚀变 成矿作用 |
| 英文关键词: epithermal gold deposits, low sulfidation, high sulfidation, hydrothermal alteration, mineralization |
| 基金项目:中央高校基本科研业务费专项资金（编号：CUGL120296）资助 |
|
| 摘要点击次数: 2232 |
| 全文下载次数: 3082 |
| 中文摘要: |
| 文章对浅成低温热液金矿床特征产物、蚀变分带、蚀变类型演化的成因及蚀变形成的主控因素进行了总结。与矿质沉淀在同一机制下形成的特征岩相和蚀变保存了成矿过程的重要信息，是有效勘查标志。低硫化型中热液爆破角砾岩、刃片状方解石/石英、细粒梳状石英及具快速冷却无序结构冰长石，是沸腾作用的产物，而沸腾同时控制金沉淀；高硫化型中蚀变以孔洞状石英、硫酸盐及粘土化等酸性淋滤产物为特征，流体酸性性质主要源于岩浆酸性挥发分在液相中的解离及SO2的歧化或氧化反应，孔洞状硅化岩是主要赋金部位，受孔洞或裂隙控制的石英中发生金矿化，它不同于岩浆酸性气水相与大气水为主流体混合形成的酸性淋滤蚀变及浸染状金矿化，而可能是由源于较深部岩浆单相流体（直接从熔体中出溶或与卤水相分离出来）浓缩形成的低温液相流体产生的。由绢英岩化到中级泥化的连续分带蚀变，有利于低硫化型金成矿；而由高级泥化到中级泥化的连续分带蚀变，对高硫化型金成矿有利。流体和围岩的性质、它们的物理化学梯度以及水岩比是控制热液蚀变最主要因素。初始流体酸碱成分对于形成的蚀变矿物组合具有决定性作用。低硫化型金成矿流体受地热系统驱动，初始富钾低酸性物质在低水岩比条件下形成以岩石缓冲为主的中碱性矿物组合；位于浅部岩浆-热液系统中或较深部岩浆气水，经过收缩或吸收大气水而形成高硫化型成矿流体，初始高酸性贫钾物质在高水岩比条件下形成流体主导的中酸性矿物组合。 |
| 英文摘要: |
| This paper reviews genesis of typical products, alteration zoning, evolution of alteration types and main controlling factors of alteration in epithermal gold deposits. Typical lithofacies and alteration formed by the same mechanism of ore material precipitation which bear lots of important information of the mineralization process, which are also effective exploration marks. Hydrothermal explosive breccia, bladed calcite or quartz, fine grained comb quartz, and adularia with disordered structure formed under rapid cooling conditions are products of fluid boiling，which also controlled gold precipitation in low-sulfidation epithermal gold deposits. Alteration in high-sulfidation epithermal gold deposits is characterized by vuggy quartz, sulfation, and clayization which are caused by acid leaching. Acidic properties are mainly originated from magmatic acidic volatile dissociation, and disproportionation or oxidation reaction of SO2 in liquid phase fluid. Euhedral quartz was controlled by holes or fractures in vuggy silicified rock, in which gold orebody formed in a way different from that generated by magmatic acid gas fluid mixing with meteoric water with acid leaching alteration and disseminated gold mineralization, instead probably generated by a kind of low temperature liquid phase fluid which contracted from deep magmatic single-phase fluid (directly exsolution from melt or separation from hypersaline phase fluid). Continuous zoning from phyllic to intermediate argillic alteration is favorable for low-sulfidation epithermal gold mineralization, while continuous zoning from advanced argillic to intermediate argillic alteration is favorable for high-sulfidation epithermal gold mineralization. Physical and chemical gradients between fluid and wall rock, individual properties, and cumulative water/rock mass ratios are important factors controlling hydrothermal alteration. The initial m(K+/H+) of magmatic-hydrothermal fluid which largely is dictated by magma composition, plays a crucial role in the formation of the altered mineral assemblages, low-sulfidation gold ore-forming fluid with initial properties of low acidity and rich potassium which is driven by the geothermal system, under rock-buffered conditions of low water/rock mass ratios formed neutral and alkalescent mineral assemblage. High-sulfidation ore-forming fluid has initial properties of low potassium and strong acidity which is located in shallow magmatic-hydrothermal systems or derived from deep magma vapor contraction or is absorbed into the meteoric water. Under fluid-dominated conditions of high water/rock mass ratios, it generates acidic mineral assemblage. |
|
查看全文
查看/发表评论 下载PDF阅读器 |
| 关闭 |
|
|
|
