2883 Ma commencement of BIF deposition at the northern edge of Congo craton, southern Cameroon: New zircon SHRIMP data constraint from metavolcanics

et al., 2002, 2007b). Typically, BIF consists of alternating Si-and Ferich layers with an evaluated total Fe and Si content of 20 -40 wt% and 43 -56 wt%, respectively (Klein, 2005).The deposition of BIF is linked to a contemporaneous process in which clastic sediments from the continent were being deposited in the ocean along with the upwelling of hydrothermal fluids at the Mid-Ocean-Ridge (MOR) (Bau and Möller, 1993;Clout and Simonson, 2005 and Beukes andGutzmer, 2008).Lavas intercalated with BIF provide a direct tool for constraining the timing of BIF formation in a paleobasin.The determination of BIF depositional age is vital to date key events in the evolution of the biosphere.Precise age constraints on the iron formation across the world both advance our understanding of BIF genesis and enable current stratigraphic and tectonic models to be evaluated.This paper dates for the first time BIF deposition within the Ntem Complex at the Northern edge of the Congo Craton by SHRIMP U-Pb method using zircons separated from associated volcanic material (Fig. 1).In addition, zircons separated from a surface BIF sample in the region are also dated to determine if other BIF depositional events occurred after the Archean phase of BIF formation.These results provide new insights for the correlation of Gondwana fragments in Africa (Congo craton) with those of South America (São Francisco craton) and also allow a better comprehension of the relation between volcanism and BIF deposition in pre-Gondwana break-up setting.the Congo Craton was associated with early arc magmatism in the Archean.These ages correlate reasonably with early BIF deposition across the Atlantic in Brazil which was once linked to the Congo craton prior to the breakup of Gondwana.