Abstract
Palaeomagnetic data from the mafic pluton of Askøy, West Norway, suggest that its original Precambrian magnetization(s) has been completely erased by Caledonian events of regional metamorphism. The present palaeomagnetic record defines two different axes of magnetization: a predominant component carried by magnetite (the B-remanence), with Dec = 025, Inc = −22 ( α 95 = 4°), and a subordinate magnetization carried by haematite (the A-remanence), with Dec = 318°, Inc = 8° ( α 95 = 10°). Comparison with Palaeozoic palaeomagnetic data for NW Europe suggests that the B-magnetization was impressed in mid-Palaeozoic time, probably in the Devonian, while the A-magnetization most likely constitutes the remains of an earlier, Upper Ordovician phase of metamorphic magnetic resetting. The palaeomagnetic evidence for metamorphic events of Ordovician and Devonian ages corroborates regional structural and reconnaissance radiometric evidence.
Published Version
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