Cambrian palaeomagnetic data from Baltica: Implications for true polar wander and Cambrian palaeogeography

A reliable Early Cambrian (c. 535 Ma) and a preliminary Late Cambrian (c. 5 00 Ma) palaeo magnetic pole from Baltica (Sweden) overlap within uncertaint y, and they are also broadly compatible with Vendian (c. 583 Ma) palaeomagn etic data. Apparent polar wander for Baltica amounts to less than 25 degree s between 583 and 500 Ma and, therefore, negates recent speculations that t he Earth tipped 90 degrees during the Early Cambrian (true polar wander). Throughout Vendian and Cambrian times. Baltica lay at southerly latitudes ( c. 30-60 degreesS). Baltica was geographically inverted, and present-day no rthern Baltica faced the NW margin of Gondwana which covered the south pole . Laurentia-Eastern Baltica and Laurentia-West Gondwana were separated by t he Iapetus Ocean, while the AEgir Sea separated Western Baltica from the Ta imyr region of Siberia. During the Cambrian Baltica probably moved eastward along the Gondwana margin, and by c. 515-520 Ma subduction in the AEgir Se a was initiated. A major event is recognized in Late Cambrian or Early Ordo vician times (c. 500 478 Ma) when Baltica must have undergone a 55 degrees counter-clockwise rotation in c. 22 million years (3 degrees /Ma). We relat e this to the early Caledonian Finnmarkian Orogeny which involved arc-conti nent collision following subduction.