Upper Kimmeridgian to Lower Tithonian foraminifers and ostracods of the Boulonnais region, Northern France. Stratigraphic and palaeoenvironmental implications and inter-regional correlations with the Siberian arctic

Climate-controlled organic matter accumulation as recorded in the Upper Jurassic Argiles de Châtillon Formation, a shallow-marine counterpart of the Kimmeridge Clay Formation

“…Here, there is no strong palynological evidence for stratification of the water column, in agreement with the trace-element analysis of Tribovillard et al (2005, 2019). Despite this, the absence of bioturbation in the paper shale intervals and the presence of solely hypoxic foraminifera assemblages (Colpaert et al 2021) points in the direction of scarce benthic life and the (temporary) absence of fully oxygenized conditions. Under these circumstances, sulfurization of OM, in particular carbohydrates, took place, as evident from the positive correlation between TOC and δ 13 C org .…”

“…Apart from the storm beds, the overall hydrodynamic regime was quite low, based on the abundant occurrence of the shallow-water foraminifer genus Ammobaculites (Colpaert et al 2021). The calcareous foraminifer genus Lenticulina dominates the foraminifera assemblages in the ORIs of the ACF, pointing to temporal hypoxia (Colpaert et al 2021). The ORIs of the ACF have been compared with the more distal time-equivalent mudstones of the KCF (Herbin et al 1991(Herbin et al , 1995Proust et al 1993;Deconinck et al 1996), but the TOC values, ranging from <1 to 8 %, are much lower in comparison.…”

“…Despite this, conditions were likely not permanently fully oxic either, as indicated by a general lack of bioturbation in the organic-rich laminated shales (Fig. 5f) and dysaerobic foraminifera assemblages, dominated by Lenticulina and Ammobaculites (Colpaert et al 2021).…”

“…4). Apart from the storm beds, the overall hydrodynamic regime was quite low, based on the abundant occurrence of the shallow-water foraminifer genus Ammobaculites (Colpaert et al 2021). The calcareous foraminifer genus Lenticulina dominates the foraminifera assemblages in the ORIs of the ACF, pointing to temporal hypoxia (Colpaert et al 2021).…”

Pourquoi continuer à chercher en paléontologie ? Le laboratoire EEP répond

“…Danelian-EEP, M. Seyler-LOG…). Ce champ d'activité relève également d'une contribution régionale (sensu lato, y compris Belgique ardennaise) : travaux sur les faunes quaternaires des Haut-de-France (Patrick Auguste), les trilobites du Dévonien du Massif des Ardennes , 2015, les foraminifères et les ostracodes du Jurassique supérieur du Boulonnais (résultats de la collaboration avec Novossibirsk, Russie ; Colpaert et al 2021).…”