Paleomagnetism of the ~860 Ma Manso dyke swarm, West Africa: implications for the assembly of Rodinia
- 1University of São Paulo, Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Geofisica, Sao Paulo, Brazil (paulantonio0931@gmail.com)
- 2Université Paul Sabatier (UPS) - Toulouse III, Observatoire Midi-Pyrénées (OMP), Géosciences Environnement Toulouse (GET), 14 Avenue Edouard Belin 31400 Toulouse – France.
- 3Ghana Geological Survey Authority, 6, 7th Avenue West Ridge, Box M80, Accra – Ghana.
- 4Universidade Federal de Ouro Preto (UFOP), Applied Isotope Research Group, Departamento de Geologia, Escola de Minas, Rua Diogo de Vasconcelos, 122, 35400-000 Ouro Preto – MG, Brazil.
- 5University of Ghana, Department of Earth Science, P.O. Box LG 58, Legon, Accra – Ghana.
- 6GEOPS, Université Paris-Sud, CNRS, Université Paris-Saclay, Rue du Belvédère, Bât. 504, 91405Orsay, France.
- 7INGEIS- Instituto de Geocronología y Geología Isotópica. Av. Int. Güiraldes, Ciudad Universitaria, Ciudad Autónoma de Buenos Aires – Argentina.
- 8Centre de Microcaractérisation Raimond Castaing, 3 Rue Caroline Aigle, 31400 Toulouse – France
The West African Craton (WAC) is one of the major cratons in the Rodinia jigsaw puzzle (~1000–750 Ma). In the Rodinian models, the position of West Africa is mainly constrained by the assumption that it had been a partner of Amazonia since the Paleoproterozoic. Unfortunately, no paleomagnetic data are available for these cratons when the Rodina supercontinent is considered tectonically stable (~1000-750 Ma). Thus, every new reliable paleomagnetic pole for the West African Craton during the Neoproterozoic times is of paramount importance to constrain its position and testing the Rodinia models. In this study we present a combined paleomagnetic and geochronological investigation for the Manso dyke swarm in the Leo-Man Shield, southern West Africa (Ghana). The ~860 Ma emplacement age for the NNW-trending Manso dykes is thus well-constrained by two new U-Pb apatite ages of 857.2 ± 8.5 Ma and 855 ± 16 Ma, in agreement with baddeleyite data. Remanence of these coarse-to-fine grained dolerite dykes is carried by stable single to pseudo-single domain (SD-PSD) magnetite. A positive baked-contact test, associated to a positive reversal test (Class-C), support the primary remanence obtained for these dykes (13 sites). Moreover, our new paleomagnetic dataset satisfy all the seven R-criteria (R=7). The ~860 Ma Manso pole can thus be considered as the first key Tonian paleomagnetic pole for West Africa. We propose that the West Africa-Baltica-Amazonia-Congo-São Francisco were associated in a long-lived WABAMGO juxtaposition (~1100–800 Ma).
Keywords: West Africa, Neoproterozoic, Tonian, Rodinia, paleomagnetism.
How to cite: Antonio, P. Y. J., Baratoux, L., Trindade, R. I. F., Rousse, S., Ayite, A., Lana, C., Macouin, M., Adu, E. W. K., Sanchez, C., Silva, M., Firmin, A.-S., Martinez Dopico, C. I., Proietti, A., Amponsah, P. O., and Sakyi, P. A.: Paleomagnetism of the ~860 Ma Manso dyke swarm, West Africa: implications for the assembly of Rodinia, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13336, https://doi.org/10.5194/egusphere-egu21-13336, 2021.
