Geological Society of London
18472 (14.05 MB)

Chapter 5 Palaeogeographic and tectonic evolution of the Arctic region during the Palaeozoic

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posted on 2016-06-21, 10:58 authored by Lawrence A. Lawver, Lisa M. Gahagan, Ian Norton

The Palaeozoic motion of the future Arctic continents is presented in the animation found in the accompanying CD-ROM. The animation shows snapshots of the motion of the tectonic blocks from 550 to 250 Ma in 3 million year steps. The locations of the blocks are controlled mainly by palaeomagnetic pole values for the blocks tied to known geological events, particularly the three main Arctic orogenies: the Scandian Caledonian which began in the Silurian, the Ellesmerian in the Late Devonian and the Uralian that began in the Late Pennsylvanian. Perhaps the most significant observation to come out of the animation is that the future Arctic continents were never very far from one another during the Palaeozoic. The maximum distance from Baltica to Laurentia may have reached 6000 km during the Middle Cambrian but the Arctic continents all surrounded the same eastern Iapetus Ocean and, by Silurian, they were quite close. Reliance on the ‘Y-loop’ palaeomagnetic data causes extremely rapid motion of Gondwana during the Silurian. Consequently the ‘X-path’ for that period is used. The palaeomagnetic poles for 422 and 406 Ma have been eliminated so that Gondwana motion is within the bounds of present day plate motion.