Bottom water redox dynamics during the Early Cretaceous Weissert Event in ODP Hole 692B (Weddell Sea, Antarctica) reconstructed from the benthic foraminiferal assemblages

Benthic foraminifera at Ocean Drilling Program (ODP) Hole 692B were studied to understand variations in oxygen and organic-matter fluxes bottom waters during the Early Cretaceous. The upper Berriasian lower Barremian black shales, characterized by high concentrations of total organic carbon (TOC) ranging between 1.3 18%, deposited an outer neritic-upper bathyal environment (~200–500 m) according benthic assemblages. A new high-resolution record foraminiferal assemblages high-latitude, dominated infaunal taxa (Citharina, Eoguttulina, Laevidentalina, Lagena, Lenticulina, Marginulina, Nodosaria, Planularia, Saracenaria, Vaginulinopsis), is described depleted‑oxygen organic‑carbon flux conditions. Extremely dysoxic conditions are recorded onset isotope excursion (CIE) marking Weissert Event (late Valanginian), followed a period anoxic waters. repopulation event foraminifera, linked increase concentrations, coincided with global cooling episode that late part Event. Subsequently, there short periods Valanginian early Hauterivian when experienced increased concentrations. Possibly, currents related influx Southern favored short-term pulses ventilation under constant Hauterivian.