Characterization of the Late Barremian in north central Tunisia: Is it a prelude to the oceanic anoxic event 1a?

During the Late Barremian, the δ13C increases sporadically and is associated with enrichments in some redox-sensitive indices U/Th, V/V + Ni, Ni/Co and V/Cr indicating the presence of intermittent dysoxic to anoxic conditions.