True polar wander during the middle Paleozoic?

Abstract

True polar wander would be recognized paleomagnetically as identical apparent polar wander paths for all surface elements. The apparent polar wander paths for the Late Ordovician-Late Devonian interval for Laurentia, Baltica and Gondwana have nearly identical looping shapes that can be brought into superposition. The paths of these continents are well documented, but even the less well known paths of South China and Siberia reveal similar lengths. The resulting reconstruction places the northern Andean margin of South America opposite the Appalachian margin of Laurentia, with Baltica and Laurentia adjoined in the fit of Bullard and colleagues. Siberia and South China would be to the north of Africa, if their paleopoles are taken at face value. For middle Paleozoic time, there is of course no information about oceanic domains, but it is interesting that all continental elements, insofar as is known, appear to have similar apparent polar wander tracks that can be plausibly superimposed without causing overlap in the positions of the continents. Albeit speculatively, because of the lack of information about the oceanic elements, it is suggested in this study that true polar wander may have occurred with a cumulative magnitude of about 75° during a 75 Ma interval, and may have been of greater magnitude than the apparent polar wander due to relative motions during the middle Paleozoic. This middle Paleozoic rate of true polar wander appears to have been an order of magnitude greater than the average rate during the late Mesozoic and Tertiary.