Date of Award

12-2015

Degree Name

Master of Science

Department

Geological and Environmental Sciences

First Advisor

Dr. Joyashish Thakurta

Second Advisor

Dr. Mohamed Sultan

Third Advisor

Dr. Heather Petcovic

Keywords

Penokean, metagabbro, ophiolite, sturgeon, Island-arc

Access Setting

Masters Thesis-Open Access

Abstract

The Sturgeon Falls Intrusive Body (SFIB) is a gabbroic intrusion located along the Michigan-Wisconsin border just south of the town of Norway, MI. The SFIB is bounded to the north by the Niagara Shear Zone and the Michigamme Formation (Schulz and Cannon, 2006) and to the south by an unnamed thrust fault zone and the Quinnesec Formation (Sims and Schulz, 1993). Field mapping has shown that the SFIB is composed almost entirely of metagabbro metamorphosed to greenschist facies, with isolated outcrops of clinopyroxenite, which are thought to be xenoliths.

The origin of the SFIB is controversial. Schulz and LeBerge (2003) argued that the SFIB and parts of the neighboring Quinnesec Formation represent a highly dismembered suprasubduction zone ophiolite. Others have argued that the SFIB was formed as an undifferentiated intrusion into the Pembine-Wausau Terrane island-arc. Field observations, geochemistry, and studies of the literature regarding the neighboring units only weakly support the ophiolite theory. Evidence gained through the course of this study suggests that the SFIB may have formed as an island arc related intrusion, similar to that of the gabbroic intrusions of the El-Aradiya area, Eastern Desert, Egypt.

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