Paleomagnetic confirmation of the “unorthodox” configuration of Atlantica between 2.1 and 2.0 Ga

Abstract

The paleogeographic evolution of the Río de la Plata Craton during the Precambrian poses important questions regarding its participation in the Atlantica continent and Columbia supercontinent. With the aim of contributing to the paleogeographic evolution of the craton in mid-Paleoproterozoic times, systematic paleomagnetic studies were carried out in late- to post-tectonic plutons of the Piedra Alta terrane (Uruguay). These yielded six new paleomagnetic poles with ages between 2.1 and 2.0 Ga that can be interpreted as integrating a single apparent polar wander path together with three previous poles from the same terrane and similar ages. The positions of the poles along the proposed path are compatible with the known ages of the intrusives from which they were computed and show a smooth distribution of magnetic polarities. Comparison of this path with those coeval from other South American and African cratons confirms previous interpretations that if the Atlantica continent ever existed, had a significantly different configuration than the originally proposed. Based on the new apparent polar wander path proposed for this different continental configuration a model of its paleogeographic evolution that suggests fast displacements in (probably southern) polar latitudes during the study time lapse is presented.