Development of an Early Palaeozoic foreland basin at the SW margin of Baltica

The microplate East Avalonia collided with Baltica from the Middle Ordovician to the Late Silurian, leading to the closure of the Tornquist Ocean. In the foreland of the collisional orogen a foreland basin was established on the Baltic shelf. The evolution of this peripheral foreland basin is documented in the ii thostratigraphy and the structural data of the Early Palaeozoic of the deep well G 14, on the island of Bornholm (Denmark), in Scania (southern Sweden) and in Pomerania (northern Poland). These outcrops represent the central to distal parts of the basin. The development of the foreland basin on the Baltic shelf was initiated by a strong subsidence in the Early Llanvirnian (Abereiddian). The distal parts of the basin are characterized by low sedimentation rates or sedimentary gaps at this time. In the Late Ordovician the subsidence continued due to the obduction of the accretionary prism onto the SW rim of Baltica and the sediment accumulation increased. Deep water sediments developed in the central and distal parts of the basin. From the mid-Llandoverian onward the relation of subsidence and sedimentation reversed and caused a gradually shallowing in the central and distal parts of the basin. Shallow marine and terrestrial sediments document the final basin fill of the foreland basin in the Late Ludlowian and Pridolian, prior to the erosional phase in the Early Devonian.