Testing the Amazônia-West Africa connection: new paleomagnetic poles for West Africa

Abstract

The Neoproterozoic era (1000 - 541 Ma) was a turning point in Earth's history. It is a period of great biological changes between the microbial Precambrian life and the Ediacaran biotic revolution with the earliest multicellular organisms. In parallel, this period is marked by a large continental reorganization (Rodinia-Gondwana transition) and by major climatic changes (snowball earth events). Due to a poor paleomagnetic database for the different cratons, the global paleogeography is controversial. In particular, for the Amazonian and West African cratons which are the two most important cratonic pieces into South America and Africa, respectively. These cratons are still associated on the basis of geological data but with no-data between 1000 Ma and 600 Ma it is impossible to test this association. New Neoproterozoic paleomagnetic poles for the Amazonian craton (Tampok dikes of ~900-800 Ma) are in progress thanks to the regular FAPESP's Post-Doctoral fellowship (2017/18840-6). The aim of this BEPE project is to obtain new key poles at ca. 900-800 Ma associated to the West African craton. In order to achieve this objective, the candidate can count on the collaboration and expertise of the GET-Toulouse laboratory team (Sonia Rousse and Lenka Baratoux, IRD) to guide us on the field-trip as well as to characterize these dikes (geochronology and petrology). The mission is planned for March 2019 to sample the well-dated Neoproterozoic dikes (U-Pb, ID-TIMS, baddeleyite ages): (1) the ~915 Ma Oda dike swarms and (2) the ~870 Ma Manso dike swarms (Baratoux et al., in press). These new data will allow one to test whether a long-connection is paleomagnetically viable between the Amazonian and West African and determine the position of these cratons within the Rodinia supercontinent. (AU)