Silver deposits, melt-inclusions, isotopes, and thermobarometry

银矿床、熔体包裹体、同位素和温压测定

• 批准号: RGPIN-2015-03912
• 负责人: Marshall, Dan
• 金额: $ 1.97万
• 依托单位: Simon Fraser University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=612651
• 关键词: Silver; deposits; melt; inclusions; isotopes

The objective of the proposed research program is to develop an enhanced understanding of how silver is speciated, transported, partitioned, and precipitated in a variety of hydrothermal environments. A series of experiments will be undertaken to test: 1) the existence of low-temperature silver-alloy melts; 2) the indirect measurement of melting temperatures of silver melt inclusions by Surface Enhanced Raman Spectroscopy (SERS); and 3) the feasibility of a using silver isotopes as a geothermometer and a fluid tracer. The first hypothesis we will test is whether silver, bismuth, and other metals can be mobilized as melts in relatively low temperature saline brines. This will be investigated via a series of piston cylinder hydrothermal experiments on silver, bismuth and other metals, and the trapping of synthetic melt and fluid inclusions. A second study will test the premise of using the 1010-fold signal strength increase of SERS, relative to standard Raman analysis, as an indirect method of determining melting temperatures of Raman inactive precious metals such as silver and gold in fluid and melt inclusions. Some of the experimental run products will be used, along with natural materials, to investigate the partitioning of 107Ag and 109Ag isotopes to determine the applicability of silver isotopes as a geothermometer. This isotope research will include the development of a protocol for silver isotope extraction from a number of economically important silver-bearing minerals. Calibration of the geothermometer will be based on the fractionation between naturally and synthetically produced mineral pairs relative to a well-characterized international silver isotope standard (NIST SRM978a), measured by high-resolution secondary ion and multi-collector inductively coupled plasma mass spectrometry. This research program builds upon my existing expertise in ore deposits, ore petrology, fluid and melt inclusions, isotopes, and experimental work and continues existing research partnerships with researchers from Australian National University and Geoscience Australia. My research team will develop and utilize new research tools and techniques to better characterize pressure, temperature, and timing of fluid mineralizing events, and advance our understanding of the role of fluid and metal melts in silver deposit formation. The results will help to improve our understanding of the evolution of the fluids in Earth’s crust, establish their relationship to tectonic and mineralizing events and enhance exploration models for silver deposits. This research program will also train next generation HQP skilled in geochemistry, ore deposits, fluid inclusions, and mineral exploration. This program will integrate our existing industry partnerships, but also create new opportunities to collaborate with industry that will enhance our research and create career opportunities for my students.

提出的研究计划的目的是提高对银在各种热液环境中如何形成、运输、分区和沉淀的理解。将进行一系列实验来检验：1)低温银合金熔体的存在；2)用表面增强拉曼光谱（SERS）间接测量银熔体包裹体的熔化温度；3)银同位素作为地温计和流体示踪剂的可行性。