The palaeomagnetism of Jersey volcanics and dykes, and the Lower Palaeozoic apparent polar wander path for Europe

Abstract

Summary. Stable natural remanent magnetization (NRM) in the Jersey Volcanics and in a single rhyolite dyke was probably acquired during the Cambrian before folding of the volcanics in the Cadomian Orogeny. After dip correction, the volcanics yield a palaeomagnetic pole at 323 E, 52 N (dp = 33, dm=35). In Jersey dolerite dykes three groups of stable NRM directions are recognized, with palaeomagnetic poles at 248' E, 26 N (dp = lo, dm = 20°), 339 E, 1 S (dp = 9, dm = 12), and 336 E, 31 S (dp = 5, dm = 9). Comparison with the European apparent polar wander path implies that stable NRM in these groups was acquired respectively during Late Precambrian or early Cambrian, Siluro-Devonian and middle Carboniferous time. The stable NRM of the Jersey lamprophyre dykes yields a palaeomagnetic pole at 322 E, 16 N (dp = 31°, dm = 38) and is probably of Silurian or Devonian age. These palaeomagnetic poles and other new data determined by the author for the Armorican Massif can be fitted to a common apparent polar wander path for Europe, and this implies that the basement of Lower Palaeozoic Europe extended from the Baltic Shield at least as far south as the Armorican Massif. The Hercynian Orogeny in these parts of Europe was therefore probably intracratonic. This polar wander path implies that in early Cambrian time the pole did not move significantly relative to Europe, but that this was followed by a large middle to late Cambrian polar shift which corresponded to rapid drift of Europe across the South Pole.