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Onset of Iberian-European plate convergence: Late cretaceous flexural response of a hot lithosphere (Aquitaine Basin, France)

Abstract : The Aquitaine Basin is closely linked to the evolution of the Pyrenees, providing precious evidences of the early stages of the Pyrenean orogeny in the Late Cretaceous. Although the timing and geometry of the Early Cretaceous rifting stage is well constrained in the Pyrenees and surrounding north Pyrenean basins, the subsequent early inversion stage has resisted characterization. In this study, we used well log correlations and interpretation of seismic reflection profiles to determine the Late Cretaceous evolution of sedimentary record in the Aquitaine Basin, spanning the transition from the postrift stage to the beginning of convergence. We identified two main deformation stages during the Late Cretaceous with radicaly different basin's geometry between the western and eastern portion of the Aquitaine Basin. The Western Aquitaine Domain (Pau area) seems to remain under this thermal subsidence regime, inherited from the postrift stage initiated in the Turonian, with little to absent deformation stages. In contrast, the Eastern Aquitaine Domain records early inversion, as indicated by the occurrence of a well-defined Campanian flexural basin. In the central Aquitaine domain (Tarbes to Saint Gaudens area), Coniacian-Santonian period is marked by the sharply increasing distinction between a very low subsiding North Aquitaine Domain (condensed sedimentation), and a strongly subsiding South Aquitaine Domain. We interpret it as a consequence of lithospheric buckling resulting from far-field compressive strain between the Eurasia and Africa plates. During the Campanian, northward convergence of the Iberia plate led to the formation of a flexural basin with a narrower, steeper geometry than the subsequent Eocene basin that formed in nearly the same region during the Pyrenean orogeny. We attribute this difference to the development of the foreland over a not thermally reequilibrated lithosphere in Campanian time, roughly 10 Myr after rifting. This inheritance of a rifted state conferred a yet non-equilibrated lithosphere being thus of very low rigidity. and a susceptibility to . Sedimentary basins formed during both the Coniacian-Santonian and Campanian to early Maastrichtian were thus accommodated by short-wavelength flexural deformation of the lithosphere, and they were subject to a distinctive deformation pattern and an immediate response to the onset of compressive strain.
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Soumis le : mercredi 21 septembre 2022 - 11:25:58
Dernière modification le : jeudi 22 septembre 2022 - 05:13:56

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Benoît Issautier, Eric Lasseur, Nicolas Saspiturry, Paul Angrand, Simon Andrieu, et al.. Onset of Iberian-European plate convergence: Late cretaceous flexural response of a hot lithosphere (Aquitaine Basin, France). Tectonophysics, Elsevier, 2022, pp.229504. ⟨10.1016/j.tecto.2022.229504⟩. ⟨hal-03782544⟩

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