Abstract

Redbeds and felsic and mafic volcanics of the King George IV Lake area of the Dunnage Zone in southwestern Newfoundland have been studied paleomagnetically. After unfolding, both hematite and magnetite carry a consistent direction of magnetization (D = 29.6°; I = 1.0°; k = 19.3; α95 = 11.3°) corresponding to a near-equitorial paleolatitude (0.5°N ± 6°) and yielding a paleopole at 84.6°E, 35.9°N (dm = 11.3°; dp = 5.6°). A positive fold test shows that the remanence was acquired before Devonian deformation. A positive conglomerate test and a reversal of the magnetization in a continuous redbed sequence demonstrates that the remanence was acquired at the time of formation, which has been assigned to the Early Silurian on the basis of a U–Pb zircon date of 431 ± 5 Ma.No other undisputed primary or pre-fold remanence has been reported from Atlantic Canada for the Late Ordovician – Silurian period. Therefore, from paleomagnetic data it is not yet possible to estimate the amount of post-Silurian movement within the Canadian Appalachians. Pre-fold magnetizations from Late Ordovician and Silurian rocks of cratonic North America predict a paleolatitude of 16°S ± 12 °for Newfoundland. However, further results are necessary to determine whether any significant displacement has occurred between Newfoundland and the craton since the Early Silurian.

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