Palaeomagnetism of the Kvanishesten and Hornelen Old Red Sandstone Basins, western Norway

Abstract

Folded Old Red Sandstone in western Norway records at least four magnetization events which testify to a prolonged thermochemical history spanning mid‐Palaeozoic to Mesozoic time. Sediments in the Hornelen and Kvamshesten basins carry a post‐tectonic remanence which is correlated with the late Palaeozoic Kiaman superchron. Many of the overprints carried by mid and Lower‐Palaeozoic rocks in Norway are reported to be significantly younger than this, and might be related to Mesozoic fault activity in the area. A second overprint identified locally in the Kvamshesten basin, adjacent to one of the present margin faults, supports the assertion. A further remanence, the integrity of which has not been previously recognized, is probably Devonian in age. Its precise age in relation to late Caledonian folding is uncertain, and therefore various geological models based on the data are offered. The simplest of these is that the remanence is post‐tectonic and that Britain and Norway attained their present relative configuration in Devonian times. Nevertheless, much of the recently obtained Middle Palaeozoic palaeomagnetic data for Norway perpetuate the longstanding discrepancy between Norwegian and British apparent polar wander (APW). Uncertainty in time calibration of the paths cannot be the sole explanation for this. The difference might be founded in post mid‐Devonian tectonism (in Norway?) or, perhaps more likely, in our understanding of the detailed APW of the relevant continents. Copyright © 1990, Wiley Blackwell. All rights reserved