Le Lias et le Dogger du sud du Bassin parisien (France) : rôle de la tectonique syn-sédimentaire et reconstitutions paléogéographiques à l'échelle de la biozone d'ammonite

The Lias and Dogger series in the southern Paris Basin outcrops are precisely dated following the ammonite biozonation scale. In these series, the depositional environment context is accurately identified and thus various isopic zones can bee recognized. From the outcrop study, the depositional sequence and the tectonics events are also distinguished. The poorly dated subsurface data should be not anymore interpreted as diagraphic signatures, with the traditional peak to peak correlation. They now need to be analysed according to the geodynamic evolution of each isopic zone. The Liassic transgressive series (in the Armorican continent) and the Dogger platforms numerous carbonate bodies are correlated at biostratigraphic scale, throughout the whole southern Paris Basin. Subsequently, paleogeographic maps are established and based on depositional sequences. The basin evolution image changes radically. This shows clearly that the complexes carbonate bodies layout prohibits any depositional environment interpretation and any isopach mapping at geological stage level. If not, the carbonate platforms of different age would be amalgamated, without any connection with the reality. Over the time, paleogeographic maps show syn-sedimentary short wavelength deformations, more or less well expressed according to the local sedimentary context. During the Lias and the Dogger, three steps can be distinguished in the southern Paris Basin. Hettangian to Lower Aalenian, the progressive increase in accommodation drives to total immersion of the continental areas; the maximum of accommodation during the Middle Toarcian entails uniform sedimentary conditions. However, short wavelength deformations persist. The major accidents defining the isopic zones are mainly North-South oriented. Middle Aalenian to Middle Bathonian, isopic zones are contrasted, controlled by the North-South accidents but also the North West-South East ones ; the variable accommodation allowed the development of regional sedimentary gaps and shallow limestone progradations on a marly area (so called “Sillon marneux”) ; tectonics events correspond to the Tethyan and the North Sea riftings influences. Upper Bathonian to Upper Oxfordian, the North West-South East tectonics accidents are particularly active; this tectonic phase could be associated to the thermal event, described in the Paris Basin and announcing the Malm depositional environment.     

Reconstitution de la végétation et du paléoclimat à partir de charbons de bois prélevés sur les sites du Paléolithique dans la région de Jungwon en Corée

Hundreds samples of the charcoals and waterlogged woods excavated from three late Paleolithic sites (Suyanggae, Gunang-gul and Sorori) in the Jungwon Region in Korea were analyzed to reconstruct the vegetation and paleoclimate in the region. Analyzed charcoal samples from the Suyanggae site show that the climate was cold in the lower part and it became more warm and dry in the upper part. From the Gunang-gul site, only Picea spp. was identified, indicating cool climates. From the Sorori site, two species were found; Alnus spp. (95%) and Ulmus spp. (5%). No conifers were discovered. The species composition indicates that the climate condition of central Korean peninsula around 8,800 BP was little cooler and wetter condition.     

Environnement et archéologie durant le Paléolithique final dans la région du Rhin moyen (Rhénanie, Allemagne) : conclusions des 15 dernières années de recherches

The Laacher See volcano erupted at 10,966 cal BC covered the whole Central Rhineland with huge tephra layers which are exploited now for some 150 years. During the last 15 years of research several new find locations exhibiting tree trunks of the hemi-boreal woodland, leaf imprints and animal tracks preserved in pumice and ashes reveal detailed insights into the (younger) Allerød environment. Five final Paleolithic (Federmessergruppen) habitation sites without any evident settlement structures but providing exogenous raw materials from outcrops in distances up to 170 km demonstrate the highly mobile mode of life of these hunter-gatherers groups some 13,000 years ago.