浅成低温热液型金矿床研究最新进展

THE LATEST ADVANCES IN THE RESEARCH OF EPITHERMAL DEPOSITS

浅成低温热液型金矿床是目前世界上最为重要的金矿床类型之一 ,也是当前国际矿床学界研究的热点之一。近年来对该类型矿床的深入研究 ,包括对该类矿床的进一步分类、流体形成演化、成矿时代、与碱性岩之间的关系 ,以及与斑岩型及其他类型矿床之间的内在联系等方面均取得了重要进展。研究表明 ,高硫化型与低硫化型金矿床不仅在矿物组合上具有显著差别 ,而且在形成的构造背景、成矿机理等方面也明显不同。高硫化型矿床主要形成于挤压应力场环境和流体混合导致成矿物质沉淀 ,而低硫化型矿床主要产于张性或中性环境下由于流体的沸腾使得矿体形成。浅成低温热液型金矿床的形成时间受其所处大地构造环境演化的控制。与浅成低温热液型金矿床有关的碱性岩通常具有相似的地球化学特征 ,即碱性岩具有异常高的氧逸度和富含挥发份。由于发现大量的浅成低温热液型金矿床与斑岩型矿床之间密切伴生 ,它们之间的内在关系正在引起越来越多矿床学家的重视 。

The Epithermal gold deposit is one of the most important types of gold deposit in the world, and also is one of the “hot spots” studied by the international economic geologists. In recent years, significant advances have been made, including the further classification of the deposit, the evolution of the ore-forming fluid, the age determination of the ore precipitation, and the relationship of the deposit with alkaline rocks, and with porphyry and other types of ore deposits. The researches indicate that the high- and low-sulphidation epithermal gold deposits not only have different mineral assemblages, but also occur in distinct tectonic settings with different ore-forming mechanism. The high sulphidation gold deposit is mainly resulted from the fluid mixing under the compressional stress regime, while the low sulphidation gold deposit from the boiling under the extensional (or intermediate) stress regime. The age of the epithermal gold deposit is predominantly controlled by the tectonic evolution. The alkaline rocks associated with the epithermal deposits have similar geochemical features, and are characterized by enriched volatile with distinctly high oxygen fugacities. As so many epithermal gold deposits are associated with the porphyry Cu-Au deposits, their genetic relationship has been highlighted by the economic geologists, and the metallogenesis should be studied further in the future.