Abstract

The determination of magnetization age is fundamental to the understanding and interpretation of paleomagnetic data from metamorphic terranes such as the Grenville Province. Assignment of absolute magnetization ages in slowly cooled rocks, although indeed possible, is difficult in practice due to variability in blocking temperatures of both magnetic and isotopic systems, and in local uplift and cooling rates. Characteristic Grenville paleomagnetic poles of likely post-metamorphic age can be grouped in a relative chronology on the basis of equal age 'thermochron' contours. These pole groups define a post-Keeweenawan loop that can explain the apparently discordant poles without invoking plate collision. As poles postdate the Grenville event, it is unlikely that paleomagnetic data from within the Grenville itself will be useful in testing collisional models for the ca. −1000 Ma orogeny.

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