Depositional history of the Devonian succession in the Pomeranian Basin, NW Poland

Evolution of the Pomeranian Basin (NW Poland) dur ing the Devonian saw the development of a characteristic siliciclastic and mixed siliciclastic-carbonate marginal marine-to-open marine carbonate sedimentary succession. This was controlled via proximity of the land areas representing uplifted parts of the East European Craton (EEC): the Fennoscandian High extending in the north, and the Mazury–Belarus High, situated in the east. The depositional history of the Pomeranian Basin began not earlier than at the end of the Emsian or possibly in the Eifelian, after a long break spanning the Lochkovian, Pragian and much of the Emsian when the area was subjected to erosion. Sedimentation started in the north eastern part with marginal-marine clastic deposits with local evaporites which are dated as uppermost Emsian?–Eifelian, passing upwards into lower–middle Givetian marginal-marine siliciclastic and carbon ate de posits; these are followed by upper Givetian marginal-marine siliciclastic rocks. In the south western part of the area, the Devonian succession started with marginal-marine carbonates and siliciclastics which belong to the upper most Emsian?–Eifelian, followed by lower and middle Givetian carbonates, passing upwards into upper Givetian marginal-marine siliciclastics. During the Late Devonian the Pomeranian Basin underwent evolution from a marginal-marine in the earliest Frasnian, through carbonate ramp or platform/shelf basin settings during the rest of the Frasnian and early Famennian, up to a reappearance of shallow subtidal and marginal-marine environments in late Famennian time. At the end of the Famennian an open shelf environment became prevalent almost over the whole area and continued up to the Mid Tournaisian. The lateral relation ships of the lithofacies during the Givetian, Frasnian and Famennian are portrayed on 11 maps, showing relatively short time-intervals, selected to depict the most sigificant environmental changes. Transgressive-re gres sive depositional cy cles ob served in the Pom er a nian Ba sin seem to have been strongly con trolled by sea level vari a tions, prob a bly of eustatic na ture; how ever, tec tonic ac tiv ity of some struc tural el e ments lo cally mod i fied the sed i men tary re cord.