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Palaeomagnetism and Palaeoclimates |
Shell, Development Company, Bellaire Research Center, P.O. Box 481, Houston Texas, 77001, USA
Amoco Production Co., P.O. Box 3092, Houston, Texas, 77253, USA
A statistical technique is described that uses the geographical distribution of lithological indicators of climate (carbonates, evaporites, coals and tillites) to estimate the past position of the geographic pole. This technique was used to estimate the movement of the South Pole across the supercontinent of Gondwana during the Palaeozoic. Our results indicate that during the Cambrian and Early Ordovician the South Pole was located adjacent to northwestern Africa. The pole moved into the Amazon Basin during the Late Ordovician and into south-central Argentina during the Silurian. Throughout the Devonian and Early Carboniferous the pole moved slowly from a location in southern Argentina to a position near the south coast of Africa. From the Late Carboniferous and into the Permian the South Pole swung eastward across central Antarctica. The Early Palaeozoic and Late Palaeozoic portions of the palaeoclimatically determined APW path are in good agreement with available palaeomagnetic data. The Middle Palaeozoic portion of the palaeoclimatically determined APW path agrees better with the palaeomagnetic data that places the South Pole in southern Argentina, than with the palaeomagnetic results that place the Devonian pole in central Africa.
