Van Ranst, G.,  Tack, L.,  Baudet, D.,  Kitambala-Yaya, N.,  Love-Pay, A. & De Grave, J. 2018. ‘Tectonic signatures of post-Gondwana break-up in the West Congo Belt (D.R. Congo): first results from low-temperature thermochronology’. CAG 27 Portugal, Aveiro abstracts: 86.

Article in a scientific Journal / Article in a Journal

Low-temperature thermochronology is the principal method to investigate tectonic movements in the upper crust. The method has been used numerous times to investigate passive margins around the South Atlantic, mainly with focus on the South American continent. On the African margins, studies have also been conducted in multiple countries (South Africa, Namibia, Cameroon, …). This study is the first to perform thermochronologic research on the western margin of the D.R. Congo. The geology in the region is dominated by the West Congo Belt, which was formed as a result of the Pan African(-Brasiliano) orogeny (c. 600 – 500 Ma). During the Early Cretaceous, with the break-up of Gondwana, the West Congo Belt evolved into a passive margin setting, with the (inherited) structural trend following a NW direction, sub-parallel to the present-day coastline. The evolution of the West Congo Belt went with episodes of tectonic reactivation during the Mesozoic and the Cenozoic. This study aims to identify these tectonic events and to place them into an absolute time frame. For this purpose we acquired samples on two E-W and two N-S profiles in the Lower Congo, consisting both of archive samples from the Royal Museum for Central Africa (Tervuren, Belgium) and newly obtained samples from a field campaign in 2016. The samples are from the Paleo - Mesoproterozoic basement (migmatites, gneisses, quartzites) or Neoproterozoic felsic intrusions or quartzites. They are analysed with the apatite fission track (AFT) and the apatite (U-Th-Sm)/He (AHe) methods. Tectonic reactivation will be mostly visible in the E-W profiles, while the N-S profiles could yield information concerning current hypotheses involving transform faults related to the opening of the South Atlantic.