SusChEM: Solubility of Iron Oxides and Gold in Acidic Hydrothermal Brines: Applications to the Origin of Iron Oxide Copper-gold Deposits

SusChEM：氧化铁和金在酸性热液中的溶解度：在氧化铁铜金矿床起源中的应用

• 批准号: 1624420
• 负责人: Christopher Gammons
• 金额: $ 11.59万
• 依托单位: Montana Technological University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-08-15 至 2019-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1624420&HistoricalAwards=false
• 关键词: SusChEM; Solubility; Iron; Oxides; Gold

As the world's population continues to expand and become increasingly industrialized, there will be a steady if not increasing need to discover new mineral deposits to provide the raw commodities that humans have come to depend on. In the case of gold, several decades of aggressive exploration by the mining industry in the 1970s and 1980s led to a global boom in the discovery of economically mineable gold deposits. However, the rate of discovery of new gold deposits has greatly declined in the past 10 years, partly because of a downturn in the industry, and partly because most of the deposits that are near surface and that fit conventional exploration models have already been discovered. This project will investigate the causative origins of a newly recognized class of hydrothermal gold deposits, referred to as 'iron oxide copper gold' (IOCG) deposits, that has the potential to generate a new cycle of exploration and discovery in the metal mining industry. Despite the fact that the IOCG class includes one of the largest metal deposits in the world - Olympic Dam, Australia - there is no consensus as to how - in a geologic, geochemical, petrologic, or plate tectonic sense - these deposits form. Part of the reason for this lack of consensus is a gap in our understanding at a fundamental, thermodynamic level of how metals such as iron, gold, and copper dissolve and precipitate in high temperature hydrothermal fluids. This project will help fill in this knowledge gap by performing several sets of hydrothermal experiments under controlled laboratory conditions. This type of study will have direct benefits to the mining industry and to society in general, which demands a steady supply of these mineral commodities. As for any scientific study that generates new, high-quality thermodynamic data, the results will also be useful to scientists in other disciplines to further understand the processes that have shaped the ancient and present-day Earth. Most researchers agree that the fluids that form IOCG deposits were hot, saline brines that were unusually oxidized: beyond this the ore deposit models diverge. This project will examine the solubility of iron oxide and gold in acidic, oxidized, saline brines at temperatures of 100 to 350 degrees C, and at oxidation states that are buffered near the aqueous ferric (Fe3+)/ferrous (Fe2+) boundary. The project will generate new thermodynamic data on the stability of aqueous ferric-, ferrous-, and gold-chloride complexes. The new data will be used to develop more accurate geochemical models for how IOCG deposits (and other types of Au-Cu-Fe deposits) form.

随着世界人口的持续增长和工业化程度的不断提高，对发现新矿藏以提供人类所依赖的原材料的需求将持续增长（如果不是不断增加）。就黄金而言，20世纪70年代和1980年代采矿业几十年来的积极勘探导致了全球经济上可开采金矿的发现热潮。然而，过去10年新金矿的发现率大幅下降，部分原因是行业低迷，部分原因是大多数接近地表且符合传统勘探模式的矿床已经被发现。该项目将调查一类新认识的热液金矿床（称为“氧化铁铜金”（IOCG）矿床）的成因，该矿床有可能在金属采矿业中产生新的勘探和发现周期。尽管 IOCG 类包括世界上最大的金属矿床之一——澳大利亚奥林匹克大坝，但从地质、地球化学、岩石学或板块构造的角度来看，这些矿床是如何形成的，尚未达成共识。缺乏共识的部分原因是我们在基本热力学层面上对铁、金和铜等金属如何在高温热液中溶解和沉淀的理解存在差距。该项目将通过在受控实验室条件下进行多组水热实验来帮助填补这一知识空白。此类研究将对采矿业和整个社会产生直接好处，因为这需要这些矿产商品的稳定供应。对于任何生成新的高质量热力学数据的科学研究，其结果也将有助于其他学科的科学家进一步了解塑造古代和当今地球的过程。大多数研究人员都认为，形成 IOCG 矿床的流体是异常氧化的热盐水：除此之外，矿床模型存在分歧。该项目将研究氧化铁和金在 100 至 350 摄氏度温度下以及在水性三价铁 (Fe3+)/亚铁 (Fe2+) 边界附近缓冲的氧化态下在酸性氧化盐水中的溶解度。该项目将生成有关水性氯化铁、氯化亚铁和氯化金络合物稳定性的新热力学数据。新数据将用于开发更准确的地球化学模型，以了解 IOCG 矿床（以及其他类型的金铜铁矿床）的形成方式。