Event Title

Oxidation and Fluid Influence in the Mesabi Iron Range: The Search for High-Grade Ore

Location

CSU 204

Start Date

9-4-2012 3:00 PM

End Date

9-4-2012 4:00 PM

Student's Major

Chemistry and Geology

Student's College

Science, Engineering and Technology

Mentor's Name

Steven Losh

Mentor's Department

Chemistry and Geology

Mentor's College

Science, Engineering and Technology

Description

For over a century, the 1.85-billion year old iron-rich sedimentary rocks of the Mesabi Iron Range of Northern Minnesota have been a major resource of high-grade iron ore to the United States. High-grade iron ore in the Mesabi Range resulted from fluids dissolving soluble minerals from the iron formation at some time in the past, before the rocks became exposed at the Earth’s surface by erosion. If these fluids had derived from the subsurface, there could be more high-grade ore at greater depths within the range. Mineral assemblages and oxidation trends within iron range samples will help determine the cause of high-grade iron ore deposition. To determine the possibility that the fluids responsible for high-grade ore flowed up from below, fluid inclusion and SEM analysis was performed on iron formation samples. Fluid inclusions are microscopic bubbles of fluid trapped in minerals as they precipitated from hot water and that, when heated or frozen under the microscope, indicate the temperature and salinity of the fluid. Scanning Electron Microscope imagery is useful in studying the interaction of mineral assemblages. Magnetite and Hematite interaction in altered rocks indicates that subsurface fluids may be directly linked to the deposition and oxidation of high-grade iron ore. From my information, it appears that there is influence between faults containing quartz and calcite veins in respect to Hematite and Magnetite grains within high-grade iron ore. Average fluid inclusion temperature and salinity is indicative of fluids of non-meteoric sources, within or below the Mesabi Iron Range.

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Apr 9th, 3:00 PM Apr 9th, 4:00 PM

Oxidation and Fluid Influence in the Mesabi Iron Range: The Search for High-Grade Ore

CSU 204

For over a century, the 1.85-billion year old iron-rich sedimentary rocks of the Mesabi Iron Range of Northern Minnesota have been a major resource of high-grade iron ore to the United States. High-grade iron ore in the Mesabi Range resulted from fluids dissolving soluble minerals from the iron formation at some time in the past, before the rocks became exposed at the Earth’s surface by erosion. If these fluids had derived from the subsurface, there could be more high-grade ore at greater depths within the range. Mineral assemblages and oxidation trends within iron range samples will help determine the cause of high-grade iron ore deposition. To determine the possibility that the fluids responsible for high-grade ore flowed up from below, fluid inclusion and SEM analysis was performed on iron formation samples. Fluid inclusions are microscopic bubbles of fluid trapped in minerals as they precipitated from hot water and that, when heated or frozen under the microscope, indicate the temperature and salinity of the fluid. Scanning Electron Microscope imagery is useful in studying the interaction of mineral assemblages. Magnetite and Hematite interaction in altered rocks indicates that subsurface fluids may be directly linked to the deposition and oxidation of high-grade iron ore. From my information, it appears that there is influence between faults containing quartz and calcite veins in respect to Hematite and Magnetite grains within high-grade iron ore. Average fluid inclusion temperature and salinity is indicative of fluids of non-meteoric sources, within or below the Mesabi Iron Range.

Recommended Citation

Rague, Ryan. "Oxidation and Fluid Influence in the Mesabi Iron Range: The Search for High-Grade Ore." Undergraduate Research Symposium, Mankato, MN, April 9, 2012.
http://cornerstone.lib.mnsu.edu/urs/2012/oral-session-13/1