Copper and Gold in Sulfur-rich Magmatic-hydrothermal Systems

岩浆热液矿床是铜和金的重要来源，但其成因仍有许多未解之谜。研究成果可为完善现有岩浆热液矿床金属勘查模式提供直接的经济效益。本项目资金将用于支持和培养经济地质学、实验地质学、热力学和数据解释方面的研究生和本科生。研究生还将指导参与该项目的初级成员。每个学生将被要求在国家科学会议上展示他们的项目部分。此外，认识到科学教育和知识传播的重要性，PI已经并将继续参与许多指导活动和推广项目，重点关注地质和矿产资源在社会中的重要性。拟议的研究将进行实验，以确定各种流体和矿物中铜和金的浓度作为温度和压力的函数，以解决这些问题。所获得的数据将增加我们对热液流体中金属的运移和形成精选矿床的降水过程的认识。实验将在500-700摄氏度和50-100兆帕的压力下进行。这个温度和压力范围连接了岩浆和热液的过渡，许多矿床被认为是在那里形成的，但目前很少有一致的数据。这个压力-温度区域具有额外的重要性，因为它代表了自然系统中超临界流体可能冷却并经历相分离成蒸汽+盐水对的部分。硫和氧的逸出度会被矿床中常见的硫化物和氧化物矿物所缓冲。评价热液中硫对矿石金属浓度和形态的重要性。这项研究还将研究在硫化物矿物形成过程中金被纳入其中的程度，以及它是如何受到硫、温度和压力变化的影响的。利用本研究获得的数据，将产生一个内部一致的热力学模型。

Magmatic-hydrothermal ore deposits are important sources of copper and gold, however, there are many outstanding questions on how these deposits form. The results of this research can provide direct economic benefits by improving existing metal exploration models associated with magmatic-hydrothermal ore deposits. Funds from this project will be used to support and train both graduate and undergraduate students in economic geology, experimental geology, thermodynamics, and data interpretation. The graduate students will also mentor the junior members involved in this project. Each student will be expected to present their portion of the project at a national scientific meeting. Furthermore, recognizing the importance of science education and the dissemination of knowledge, the PI has and will continue to participate in numerous mentoring activities and outreach programs focused on the importance of geology and mineral resources in society.The proposed study will conduct experiments to determine the concentrations of copper and gold in various fluids and minerals as a function of temperature and pressure to address these questions. The data obtained will increase our understanding on the transportation of metals in hydrothermal fluids and the process of precipitation responsible for the formation of select ore deposits. Experiments will be conducted from 500-700 degrees Celsius and pressures from 50-100 MPa. This temperature and pressure range that bridges the magmatic to hydrothermal transition where many deposits are thought to form but where few consistent data are currently available. This pressure-temperature region has added importance because it represents portions of natural systems where a supercritical fluid may cool and undergo phase separation into a vapor + brine pair. The sulfur and oxygen fugacity will be buffered by sulfide and oxide minerals commonly found in ore deposits. The importance of sulfur in hydrothermal fluids on ore metal concentrations and speciation will be evaluated. This study will also examine the extent to which gold is incorporated into sulfide minerals during their formation and how it is impacted by changes in sulfur, temperature, and pressure. An internally consistent thermodynamic model will be generated by using the data obtained in this study.