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

Abstract

Evolution of the Pomeranian Basin (NW Poland) during 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 northeastern 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 carbonate deposits; these are followed by upper Givetian marginal-marine siliciclastic rocks. In the southwestern part of the area, the Devonian succession started with marginal-marine carbonates and siliciclastics which belong to the uppermost 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 relationships of the lithofacies during the Givetian, Frasnian and Famennian are portrayed on 11 maps, showing relatively short time-intervals, selected to depict the most significant environmental changes. Transgressive-regressive depositional cycles observed in the Pomeranian Basin seem to have been strongly controlled by sea level variations, probably of eustatic nature; however, tectonic activity of some structural elements locally modified the sedimentary record.