Late Ediacaran paleogeography of Avalonia and the Cambrian assembly of West Gondwana

The latest Proterozoic tectonic evolution of Avalonia, one of the largest peri-Gondwanan terranes, bears on the issue of Gondwana amalgamation during the transition from Rodinia to Pangea. New paleomagnetic results from mid–late Ediacaran strata in the Newfoundland sector of Avalonia confirm substantial apparent motion of that terrane between ca. 590 and 560 Ma, consistent with a true polar wander interpretation for that interval. When the Avalonian poles are mapped onto complementary paleomagnetic records from West Africa and Laurentia, the Avalonia terrane may occupy any of four possible positions, all of which are far-removed from those cratons. Choosing the most kinematically parsimonious location leading toward Gondwana assembly, we find that Avalonia was most likely proximal to Amazonia during the Ediacaran–Cambrian transition, with a substantial (∼3000 km) separation between Amazonia and West Africa at that time. Our results thus favor the existence of a wide Clymene Ocean and subsequent Cambrian final assembly of West Gondwana, providing a key snapshot onto the evolving Rodinia-Gondwana supercontinental transition

Phanerozoic polar wander, palaeogeography and dynamics

A significant number of new palaeomagnetic poles have become available since the last time a compilation was made (assembled in 2005, published in 2008) to indicate to us that a new and significantly expanded set of tables with palaeomagnetic results would be valuable, with results coming from the Gondwana cratonic elements, Laurentia, Baltica/Europe, and Siberia. Following the Silurian Caledonian Orogeny, Laurentia's and Baltica's Apparent Polar Wander Paths (APWPs) can be merged into a Laurussia path, followed in turn by a merger of the Laurussia and Siberia data from latest Permian time onward into a Laurasian combined path. Meanwhile, after about 320. Ma, Gondwana's and Laurussia/Laurasia's path can be combined into what comes steadily closer to the ideal of a Global Apparent Polar Wander Path (GAPWaP) for late Palaeozoic and younger times. Tests for True Polar Wander (TPW) episodes are now feasible since Pangaea fusion and we identify four important episodes of Mesozoic TPW between 250 and 100. Ma. TPW rates are in the order of 0.45-0.8°/M.y. but cumulative TPW is nearly zero since the Late Carboniferous. With the exception of a few intervals where data are truly scarce (e.g., 390-340. Ma), the palaeomagnetic database is robust and allows us to make a series of new palaeogeographic reconstructions from the Late Cambrian to the Palaeogene. © 2012 Elsevier B.V

New paleomagnetic data from Late Neoproterozoic sedimentary successions in Southern Urals, Russia: implications for the Late Neoproterozoic paleogeography of the Iapetan realm

We present the results of paleomagnetic study of Ediacaran sedimentary successions from the Southern Urals. The analysis of the sedimentary rocks of the Krivaya Luka, Kurgashlya and Bakeevo Formations reveal stable mid-temperature and high-temperature remanence components.Mid-temperature components were acquired during Devonian (Bakeevo Formation) and Late Carboniferous–Early Permian remagnetization events. The high-temperature components in Kurgashlya and Bakeevo Formations are interpreted to be primar , because they are supported by a positive conglomerate test (Bakeevo Formation) and magnetostratigraphic pattern (Kurgashlya Formation). Thehigh-temperature component in the Krivaya Luka Formation is interpreted to be a Late Ediacaran overprint. Our new paleomagnetic poles together with some previously published Ediacaran poles from Baltica and Laurentia are used herein to produce a series of paleogeographic reconstructions of the opening of the Iapetus Ocean