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，对发现新的矿藏以提供人类赖以生存的原材料的需求将不断增加。以黄金为例，采矿业在1970年代和1980年代进行了几十年的积极勘探，导致全球发现经济上可开采的金矿的热潮。然而，在过去10年中，新金矿的发现率大大下降，部分原因是该行业的衰退，部分原因是大多数接近地表并符合传统勘探模式的矿床已经被发现。该项目将调查一种新认识的热液金矿床的成因，这种矿床被称为“氧化铁铜金”（IOCG）矿床，有可能在金属采矿业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--但在地质学、地球化学、岩石学或板块构造意义上，这些矿床是如何形成的还没有达成共识。这种缺乏共识的部分原因是我们在基本的热力学水平上对铁，金和铜等金属如何在高温热液流体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几组热液实验来帮助填补这一知识空白。这类研究将直接有益于采矿业和整个社会，因为社会需要这些矿产品的稳定供应。至于任何产生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现代地球的过程。大多数研究人员都认为，形成IOCG矿床的流体是热的盐水，这些盐水被异常氧化：除此之外，矿石存款模型存在分歧。该项目将研究氧化铁和金在100至350摄氏度的温度下在酸性氧化盐水中的溶解度，以及在水溶性铁（Fe 3+）/亚铁（Fe 2+）边界附近缓冲的氧化态。该项目将产生新的热力学数据的稳定性水铁，亚铁，和金氯化物复合物。新的数据将用于开发更准确的地球化学模型，以了解IOCG矿床（和其他类型的Au-Cu-Fe矿床）的形成。