Browsing by Subject "ore deposits"

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    From Compass to Drone: The Evolving Role of Magnetics in Mapping the Geology and Ore Deposits Of the Lake Superior Region: 1830-2022
    (Minnesota Geological Survey, 2022) Hinze, William J
    The Lake Superior region, the “Birthplace of North American Precambrian Geology,” is noted for its world-class mineral resources, especially its native copper and iron ore deposits, and its classic bedrock of Archean and Proterozoic orogenic belts and the exposures of rocks of the Midcontinent Rift System. The magnetic method of mapping the region’s ore deposits and bedrock geology has been used for nearly two centuries because of limitations in the exposure of the Precambrian bedrock in the region. For the first century magnetic mapping was directed primarily at the identification of regions favorable for iron and copper ore deposits using simple magnetic needle instrumentation. Initially instrumentation was limited to the use of the dial (sun) compass and used mainly for exploration of hard, magnetite-rich iron ore deposits. With the introduction of the dip needle, a counterbalanced magnetic needle oscillating vertically in the magnetic meridian, to the Lake Superior region likely in 1865 by T.B. Brooks, magnetic mapping was no longer restricted to the difficult to interpret magnetic field angular variations.
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    Guidebook 20. Field Trip Guidebook for the Geology and Ore Deposits of the Midcontinent Rift in the Lake Superior Region
    (Minnesota Geological Survey, 1995) Miller, James D., Jr.
    This guidebook has been prepared for the field conference and symposium on "The Petrology and Metallogeny of Volcanic and Intrusive Rocks of the Midcontinent Rift System" that will be held in Duluth, Minnesota in August of 1995 as part of International Geological Correlation Program (IGCP) Project 336 ("Petrology and Metallogeny of Mafic and Ultramafic Magmatism"). The four-year-Iong IGCP project was begun in 1992 to investigate the petrology and metallogeny of various intracontinental mafic igneous provinces with an overall goal of establishing geological criteria for targeting mineral deposits in such environments. The principal goal of the 1995 meeting is to showcase to the international scientific and exploration communities the significant advances in our understanding of the structure, mineralization, and magmatic history of the Midcontinent rift. Toward this end, three field trips have been organized around the three-day symposium to be held August 25-27, 1995 in Duluth. The field trips are designed to provide a broad overview of the geologic framework of the Midcontinent rift, where it is best exposed in the western Lake Superior region. Field trip I (August 19 -24) looks at the physical volcanology of the flood basalts exposed on Isle Royale. Field trip II (August 22-24) highlights the stratigraphy, structure and mineralization of the volcanic and sedimentary rocks forming the southern limb of the Midcontinent rift in Wisconsin and Upper Michigan. The post-symposium field trip ill (August 28-September 1) focusses on the geology and ore deposits associated with the intrusive rocks of the Midcontinent rift exposed along the north shore of Lake Superior in Minnesota and Ontario.