0000000000648165
AUTHOR
Chantal Bourdillon
Unravelling the PETM record in the Sparnacian facies of NW Europe: new data from the north-eastern Paris Basin
The geological archives record "hyperthermic" crises, along with their consequences on the biota and physical environment. Among these, the PETM (Paleocene-Eocene Thermal Maximum) is considered as the closest analogue to the current climate crisis due to its global character and the speeds at which the CO2 rate and average temperatures increased. Some 55.8 Ma ago (Aubry et al., 2007), it affected the Earth for a period of almost 200,000 years; the terrestrial and marine paleoenvironments were marked by a negative δ13C anomaly (or Carbon Isotopic Excursion, CIE) coinciding with a negative δ18O anomaly indicative of a drastic temperature rise (+ 3 to + 8 °C). The causes envisaged to explain t…
Sur la structure, l'âge et l'origine des « brèches de Bosmendiette » (Pyrénées-Atlantiques)
Resume Anterieurement attribuees a l'Albo-Aptien et considerees comme resultant du diapirisme des evaporites triasiques, les breches de Bosmendiette se seraient, pour certains auteurs recents, mises en place au Selandien (Paleocene), dans des canyons sous-marins etablis au sein d'un profond sillon, le long de la chaine des Pyrenees, du Roussillon jusqu'a l'Atlantique. Leur âge serait fonde sur la decouverte d'une riche microfaune pelagique de globigerinides. Nos recherches montrent qu'azoiques a leur base, pourvues de radiolaires et de rares foraminiferes benthiques au sommet, ces breches resultent en realite de la destruction de boucles de slumps affectant l'« Infralias ». Recouvertes en o…
Incised valleys and tidal seaways: the example of the Miocene Uzès-Castillon basin, SE France.
Abstract The sedimentology and stratigraphy of the Miocene deposits of the Uzès-Castillon basin are revisited. This basin, located in SE France at the junction between the perialpine foreland basin and the W Mediterranean margin, sits in a syncline that formed during the latest Cretaceous Pyrenean tectonic phase. It records the succession of shallow-water mixed siliciclastic to dominantly bioclastic carbonates that alternate with shelf marls. The clastic carbonates were accumulated as a stack of subtidal dunes and bars that were formed by tidal currents channelized in a seaway following the syncline axis. The marls indicate deposition in more protected and locally deeper waters, as interflu…