| Summary: | We present new paleomagnetic data from three Middle Neoproterozoic carbonate units of East Svalbard, Norway. The paleomagnetic record is gleaned from 50 to 650 m of continuous, platformal carbonate sediment, is reproduced at three locations distributed over >100 km on a single craton, and scores a 5–6 (out of 7) on the Van der Voo (1990) reliability scale. Two >50° shifts in paleomagnetic direction are coincident with equally abrupt shifts in δ^(13)C and transient changes in relative sea level. We explore four possible explanations for these coincidental changes: rapid plate tectonic rotation during depositional hiatus, magnetic excursions, nongeocentric axial-dipole fields, and true polar wander. We conclude that the observations are explained most readily by rapid shifts in paleogeography associated with a pair of true polar wander events. Future work in sediments of equivalent age from other basins can test directly the true polar wander hypothesis because this type of event would affect every continent in a predictable manner, depending on the continent's changing position relative to Earth's spin axis. © 2006 Geological Society of America. Manuscript Received 28 August 2005. Revised Manuscript Received 27 April 2006. Manuscript Accepted 30 April 2006. This work was supported by the National Science Foundation (Arctic Natural Sciences Research Program grant OPP-9817244), the National Aeronautics and Space Administration (NASA) Astrobiology Institute, the Canadian Institute for Advanced Research (Earth System Evolution Project), the Tectonics Special Research Centre (Perth, Australia), and the Agouron Institute. Critical reviews from John Geissman, Arlo Weil, Joseph Meert, David Bice, and Rob Van der Voo improved the manuscript. Additionally, the paper benefited from useful discussions with David Barbeau, Thorsten Becker, Michael Bender, Jeremy Bloxham, Sam Bowring, Bruce Buffett, Mathieu Dumberry, David Evans, David Fike, John Grotzinger, Ebbe Hartz, John Hayes, Matthew Hurtgen, David Jones, Jamie ...
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