Magnetization of Keweenawan rocks near Duluth, Minnesota

C.E. Jahren

doi:10.1190/1.1439660

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Magnetization of Keweenawan rocks near Duluth, Minnesota

C.E. Jahren

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Abstract

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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Geophysics Article

Source-reported bounding extent: 46.74738913515841° to 46.882723010671945° latitude; -92.252197265625° to -92.098388671875° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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C.E. Jahren. 1965. Magnetization of Keweenawan rocks near Duluth, Minnesota. https://doi.org/10.1190/1.1439660

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