Formation of Magmatic-hydrothermal Veins: Interpreting Quartz Textures and Vein Mineral Assemblages in the Butte, Montana porphyry Copper System

GSTDTAP

项目编号	1524665
	Formation of Magmatic-hydrothermal Veins: Interpreting Quartz Textures and Vein Mineral Assemblages in the Butte, Montana porphyry Copper System
	Mark Reed
主持机构	University of Oregon Eugene
项目开始年	2015
	2015-06-15
项目结束日期	2018-05-31
资助机构	US-NSF
项目类别	Continuing grant
项目经费	124150(USD)
国家	美国
语种	英语
英文摘要	Magmatic-hydrothermal fluids in the crust transport and deposit ore metals in some settings, and in other settings, they feed hot water into high-temperature geothermal systems used to produce electricity. Exactly how minerals precipitate in these environments is not well understood because the processes operate at depths and on timescales that are not accessible to direct observation. To understand how, when, and where rock fractures form and then fill with minerals, especially quartz, the investigators in this study are examining veins in a large ore deposit exposed on Earth's surface. Studies supported by this award consist of mapping the vein pattern, and determining the mineral assemblages, then imaging the textures of crystals, measuring the properties of fluids trapped in the crystals, and determining the abundances of trace elements within those crystals. These measurements reveal the temperature, depth and growth histories of the crystals. In this study, the large and well characterized hydrothermal system in Butte, Montana serves as a natural laboratory for investigating how magmatic-hydrothermal veins fill with quartz, sulfides and magnetite. The mechanisms and timescales of vein formation are addressed by (1) mapping the distribution of quartz-dominated veins and variations in alteration of the host rock adjacent to these veins, (2) analyzing quartz vein textures and compositions using a suite of analytical tools (SEM, SEM-CL, SEM-EBSD, and EPMA), (3) estimating temperature and pressure of mineral formation using trace element and fluid inclusion thermometry, and (4) conducting hydrothermal quartz growth experiments in the laboratory to assess the influence of crystal growth rate on the Ti-in-quartz thermometer. The combined data set addressing SEM-CL textures (mottled vs. banded euhedral), EBSD (addressing crystal orientations), fluid inclusion homogenization temperatures, and the P-T interpretations of Ti-in-quartz, Zr-in-rutile and Ti-in-biotite from EPMA will constrain the interplay of fluid flow, heat transfer, and quartz precipitation in ways that provide new insights into how magmatic hydrothermal systems work.
来源学科分类	Geosciences - Earth Sciences
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/68058
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	Mark Reed.Formation of Magmatic-hydrothermal Veins: Interpreting Quartz Textures and Vein Mineral Assemblages in the Butte, Montana porphyry Copper System.2015.