Paleozoic history of the Kara microcontinent and its relation to Siberia and Baltica: Paleomagnetism, paleogeography and tectonics

摘要

The tectonic history of the Kara microcontinent on the northern part of the Taimyr-Sevemaya Zemlya region, Siberian Arctic, has been the subject of considerable dispute, especially with respect to whether it was attached to Siberia or Baltica, or was an independent plate during the Late Neoproterozoic and Early Paleozoic. One way to resolve this controversy is by quantitative paleomagnetic data, and in this article, we present the results of a paleomagnetic study of Early Paleozoic strata from October Revolution Island in the Severnaya Zemlya Archipelago, which allow definition of the paleogeographic position of the Kara microcontinent during the Early Paleozoic. Paleomagnetic poles for three consecutive time intervals, i.e., Late Cambrian-Early Ordovician, Middle-Late Ordovician and Late Silurian, have been determined. These new data demonstrate that Kara was not part of Siberia or Baltica during the Early Paleozoic, but support models that it was an exotic microcontinent with an independent tectonic history. The Paleozoic tectonic evolution of the Kara microcontinent was dominated by strike-slip displacements associated with a transform margin that resulted in collision with the Siberian craton in the Late Carboniferous to Permian. This interpretation provides a new foundation to explain the Paleozoic history of the Kara microcontinent. (c) 2005 Elsevier B.V. All rights reserved.