Date of Award

4-2016

Degree Name

Master of Science

Department

Geological and Environmental Sciences

First Advisor

Dr. Joyashish Thakurta

Second Advisor

Dr. R. V. Krishnamurthy

Third Advisor

Dr. Robert Gillespie

Keywords

Eagle, sulfide, isotopes, intrusion, geochemistry

Access Setting

Masters Thesis-Open Access

Abstract

The Eagle magmatic intrusion is located in the Upper Peninsula of Michigan in Marquette County. It hosts a high grade magmatic nickel-copper sulfide ore deposit. Country rocks surrounding the Eagle intrusion are metamorphosed slate and greywacke of the Proterozoic Michigamme Formation and Archean granite-gneiss. The aim of this thesis is to characterize the magmatic sulfide mineral deposit at Eagle and to establish its relationship to the surrounding host rocks of the Baraga Basin area.

The Eagle East intrusion is located 600 meters east of the Eagle intrusion. These two intrusions are similar in composition and sulfide mineralization. Sulfide textural domains at both intrusions have been separated into three groups: (1) disseminated, (2) semi-massive, and (3) massive sulfide. δ34S values from the sulfide units within the two intrusions range from 0‰ to 5‰ Vienna Canyon Diablo Troilite (VCDT). δ34S values from country rocks of the Proterozoic Michigamme Formation range from 6‰ to 20‰. Archean granite-gneiss have δ34S values ranging from -11‰ to 7‰. Slightly higher δ34S values from sulfides hosted in the intrusions are indicative of primitive mantle magmas of 0‰ interacting with sulfide liquid derived from crustal rocks. Mixtures of sulfide sourced from Michigamme Formation rocks and Archean granite-gneiss could have also averaged the δ34S values between 0‰ to 5‰ for sulfide ores found within the intrusions.

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