The Lower-Middle Ordovician palaeofield of Scandinavia: southern Sweden 'revisited'

We present a palaeomagnetic pole for the Arenig-Llanvirn Swedish Orthoceras Limestones based on a new analysis of some earlier reported palaeomagnetic data. This new pole, 18° N and 046° E, differs from the original estimate of 30° N and 46° E. The revised pole probably represents the most reliable Ordovician pole from Baltica, although some uncertainties remain concerning the relative importance of diagenetic/depositional controls on remanence acquisition. Based on the new pole from the Swedish Orthoceras Limestone and recent palaeomagnetic results from the northern Scandinavian Caledonides, it is now evident that Baltica lay within southerly latitudes of between 30 and 60° S in Cambro-Ordovician times. Subsequent anticlockwise rotation relative to eastern Avalonia (southern Britain) may indicate dextral shear across the Tornquist suture prior to Mid-Late Ordovician amalgamation of eastern Avalonia and Baltica.