| Summary: | International audience The Late Cretaceous to early Palaeogene is a period of major deformations of the western part of the Eurasian plate within both the context of the Africa-Eurasia convergence and the North Atlantic opening. Two mechanisms are proposed: (1) surface upwelling caused by flows in the underlying mantle (Iceland Plume upwelling) and/or (2) horizontal lithospheric deformations (Africa, Iberia, Eurasia convergence). Here we discuss the timing, spatial distribution, types and magnitude of these deformations. Two approaches are used:(1) Geomorphology - on the mapping and chronology of all the macroforms (planation surfaces, incised rivers) dated by intersection with the preserved sediments, weathering and volcanics;(2) Basin stratigraphy and structural analysis - on a more classical dataset of seismic lines, wells and field observations, coupled with biostratigraphic re-evaluations.We provide an european-scale cross section that has been restored from the early Turonian to the Oligocene, through the North Pyrenean Zone, Eastern Aquitaine Basin, French Massif Central and Paris-Brussels Basins. We combine two methods to quantify the magnitude of the deformations: (1) depositional domain - 2D accommodation space measurements; (2) erosional domain - difference between the present-day elevation of ancient sea-level markers (marine sediments scattered upon it) and a global sea-level curve.The first outcomes of our study are:- The Late Cretaceous is a period of enhanced subsidence. All the studied area is covered by marine chalk deposits.- A major period of deformation occurs at the Cretaceous-Tertiary boundary possibly sub- divided into two sub-periods: intra-Maastrichtian - pre-middle-Danian and Upper Danian - pre-Thanetian.- Long wavelength (x 100 km) and moderate amplitude uplift (x 100 m) coupled with intense erosion affects the northern border of the French Massif Central and the Paris and Brussels Basins. A major change in the sedimentary system occurs from open marine chalks to siliciclastic shore ...
|
|---|