Browsing by Subject "Basalt dikes"

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    Investigation of Kaolin in Eastern Redwood County, Minnesota, Using Gravity, Magnetic, and Electrical Resistivity Methods
    (University of Minnesota Duluth, 1990-10) Chandler, Val W; Hauck, Steven A; Severson, M; Heine, John J; Reichhoff, J; Schaap, Bryan D
    The utility of gravity, magnetic and electrical resistivity methods for kaolin exploration was evaluated on a test-drilled 300-meter by 600-meter prospect in the Minnesota River Valley in eastern Redwood County, Minnesota. Seven Wenner soundings and three resistivity profiles were taken over the prospect, and interpretations were constrained by direct determinations at nearby bedrock exposures and by drill hole (regolith) data. High-precision gravity data also appear to reflect thickness variations in the low-density kaolin. The magnetometer is not sensitive to the kaolin itself, but it may be useful in detecting rocks in the protolith that yield chlorite-rich, weathered clays, such as diabase dikes.