Formation of the Iberian-European Convergent Plate Boundary Fault and Its Effect on Intraplate Deformation in Central Europe

Armin Dielforder (1) , Gianluca Frasca (1, 2) , Sascha Brune (3) , Mary Ford (1, 4)

1 CRPG - Centre de Recherches Pétrographiques et Géochimiques
2 IPGS - Institut de physique du globe de Strasbourg
3 GFZ - German Research Centre for Geosciences - Helmholtz-Centre Potsdam
4 ENSG - Ecole Nationale Supérieure de Géologie

With the Late Cretaceous onset of Africa-Iberia-Europe convergence Central Europe experienced a pulse of intraplate shortening lasting some 15-20 Myr. This deformation event documents area-wide deviatoric compression of Europe and has been interpreted as a far-field response to Africa-Iberia-Europe convergence. However, the factors that governed the compression of Europe and conditioned the transient character of the deformation event have remained unclear. Based on mechanical considerations, numerical simulations, and geological reconstructions, we examine how the dynamics of intraplate deformation were governed by the formation of a convergent plate boundary fault between Iberia and Europe. During the Late Cretaceous, plate convergence was accommodated by the inversion of a young hyperextended rift system separating Iberia from Europe. Our analysis shows that the strength of the lithosphere beneath this rift was initially sufficient to transmit large compressive stresses far into Europe, though the lithosphere beneath the rift was thinned and thermally weakened. Continued convergence forced the formation of the plate boundary fault between Iberia and Europe. The fault evolved progressively and constituted a lithospheric-scale structure at the southern margin of Europe that weakened rheologically. This development caused a decrease in mechanical coupling between Iberia and Europe and a reduction of compressional far field stresses, which eventually terminated intraplate deformation in Central Europe. Taken together, our findings suggest that the Late Cretaceous intraplate deformation event records a high force transient that relates to the earliest strength evolution of a lithospheric-scale plate boundary fault.

Mots clés: intraplate deformation; orogeny; plate boundary fault; plate coupling force; Pyrenees; lithosphere dynamics

Domaines: Planète et Univers [physics]; Sciences de la Terre

Armin Dielforder, Gianluca Frasca, Sascha Brune, Mary Ford. Formation of the Iberian-European Convergent Plate Boundary Fault and Its Effect on Intraplate Deformation in Central Europe. Geochemistry, Geophysics, Geosystems, 2019, 20 (5), pp.2395-2417. ⟨10.1029/2018GC007840⟩. ⟨insu-03619835⟩