Refined timing and kinematics for Baltica-Avalonia convergence based on the sedimentary record of a foreland basin

The Caledonian foreland basin of Poland onlaps the SW slope of the East European Craton and is elongated in a NW-SW direction along the margin of the Baltica palaeocontinent. The base of the synorogenic clastic wedge rises in age from Llandovery to Ludlow between NW and SE Poland, respectively. As the initial influx of orogen-derived detritus can be unequivocally identified, this diachronism documents a southeastward migration of the basin depocentre, parallel to the present-day Caledonian Deformation Front. Our best-fit plate model shows an oblique collision of Baltica and Avalonia, the latter initially indenting the Baltica margin in the NW. Afterwards, Baltica was progressively underthrust beneath Avalonia towards the SE in response to the oblique soft-mode closure of the Tornquist Ocean. The final deformation event within the Caledonian foreland took place in the earliest Devonian as a far-field effect of sinistral orogen-parallel displacements along the Iapetus suture.