Palaeomagnetic constraints on the position of Gondwana during Ordovician to Devonian times

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Abstract
The currently available palaeomagnetic data base for Gondwana is reviewed and using revised rotation parameters for the fit of the southern continents an attempt has been made to construct an apparent polar wander path for Gondwana during Ordovician to Permo-Carboniferous times using a cubic spline fitting technique. Although the density of the data set is still rather sparse and the quality of the data is variable, our approach seems to be justified when tying the apparent polar wander path to selected palaeopoles of high quality. The palaeogeographic scenario based on our results is rather complex. Rapid northward shift of Gondwana during the Ordovician to the Early Silurian and subsequent collision with Laurentia is followed by divergence and the formation of a wide intervening ocean during the Devonian. The final closure of this ocean did not begin before the Late Devonian and was completed by the Late Carboniferous. If the apparent polar wander path presented in this paper is correct, then extremely high drift rates of about 23 cm a -1 have to be postulated for Gondwana during the Late Ordovician-Silurian.