First record of early Aptian Oceanic Anoxic Event 1a from the Paris Basin (France) - Climate signals on a terrigenous shelf

Abstract In 2013, Andra (French National Radioactive Waste Management Agency) drilled boreholes to the south-east of the Paris Basin, to characterise Aptian and Albian clayey formations, including the ‘Argiles a Plicatules’ Formation dated as early Aptian. One of these boreholes intersected this formation with an excellent recovery allowing detailed biostratigraphy (ammonites), sedimentology, clay mineralogy, isotope geochemistry (δ13Corg) and Rock-Eval analyses to be performed. The base of the formation corresponds to transgressive dark-grey silty clays with iron oolites and plant debris indicating a coastal environment evolving up-section to upper offshore environments. Higher in the succ…

Lower Aptian climate and recording of the oceanic anoxic event 1a on the terrigenous shelf of the Paris Basin.

Is there an orbital control on the pacing of anoxia across the Aptian-Albian boundary (~113 Ma)?

<p>The stratigraphic interval spanning the Aptian-Albian transition is marked by a cluster of short-lived marine anoxic episodes referred to as Oceanic Anoxic Event 1b (OAE 1b). These short-lived episodes are, from the oldest to the youngest, the Jacob, Kilian, Paquier and Leenhardt events. We here aim at testing the impact of the long Milankovitch cycles (1.2-Myr and 2.4-Myr) on the recurrence of these oxygen-deficiency episodes by establishing a precise astrochronology of the OAE 1b interval from the Col de Pré-Guittard section (Albian GSSP, Vocontian Basin, SE France). The section belongs to the “Marnes Bleues Formation”, which is a …