Preliminary Magnetostratigraphic and Isotopic Dating of the Ngwa Formation (Dschang Western Cameroon)Benammi M1*, Hell JV2, Bessong M2, Nolla D2, Solé J3 and Brunet M1,4
- *Corresponding Author:
- Benammi M
Institut de Paléoprimatologie,
Paléontologie Humaine: Évolution et Paléoenvironnements (IPHEP)
UMRCNRS 7262, Bâtiment B35, 6 rue Michel.Brunet, 86022 Poitiers Cedex,
Tel: + 56187897
E-mail: [email protected]
Received date: December 22, 2016; Accepted date: February 17, 2017; Published date: February 23, 2017
Citation: Benammi M, Hell JV, Bessong M, Nolla D, Solé J, et al. (2017) Preliminary Magnetostratigraphic and Isotopic Dating of the Ngwa Formation (Dschang Western Cameroon). J Geol Geophys 6:282. doi: 10.4172/2381-8719.1000282
Copyright: © 2017 Benammi M, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
A magnetostratigraphic study has been carried out to constrain the age of the volcano-sedimentary Ngwa formation in the eastern part of the Dschang region. A stratigraphic section of about 80 meters thick corresponding to 26 sites has been sampled, and it is composed mainly of fine-grained sandstones, clays, lignite, volcanic sediment and tuffs. A magnetic study conducted on 56 samples shows one or two components of magnetization carried either by titanomagnetite, magnetite and Fe-sulphide. The section that was sampled shows one normal polarity and one reversed polarity. In the lower part of the section, a K-Ar radiometric dating was performed on the plagioclase minerals isolated from the tuffs level situated about 15 meters above the lignite seam, and gave an age of 20.1 ± 0.7 Ma. Constrained by this age, the observed polarity zones can be readily correlated with chrons C6An.1n-C6An.1r of the GPTS. This study suggests that the age of the lignite is comprised between 20.04 Ma and 20.21 Ma. The mean direction of the characteristic remanent magnetization documents a counterclockwise vertical axis rotation of about 8° with respect to the expected Lower Miocene direction derived from the Africa polar wander curve.