Magnetization of Keweenawan rocks near Duluth, Minnesota




Remanent magnetization measurements on 200 oriented samples from the Keweenawan gabbro, diabase, and associated rocks in the Duluth area show a clustering of directions west-northwest and downward. Gabbro samples magnetized in this direction usually have Q, the ratio of remanent to induced magnetization, up to five, whereas other gabbro samples have larger Q. Diabase shows no such generalization. Remanent magnetization is important in all rocks studied. Q ranges from 0.3 to 75, but is less than 1.0 in only 15 samples. Volume magnetic susceptibility averages range from 0.3 × 10-3 to 6.0 × 10-3. There is no apparent correlation between magnetic susceptibility and the direction of remanent magnetization. Average directions of remanent magnetization indicate a Keweenawan geomagnetic north pole at latitude 30° to 34° N, longitude 175° to 180° W. 

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Publication type Article
Publication Subtype Journal Article
Title Magnetization of Keweenawan rocks near Duluth, Minnesota
Series title Geophysics
DOI 10.1190/1.1439660
Volume 30
Issue 5
Year Published 1965
Language English
Publisher Society of Exploration Geophysicists
Description 17 p.
First page 858
Last page 874
Country United States
State Minnesota
City Duluth
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