The Late Cretaceous tectono-sedimentary evolution of northern Poland – A seismic perspective on the role of transverse and axial depositional systems during basin inversion

Abstract

This paper describes a new tectono-sedimentary model of the Late Cretaceous evolution of the northern, peripheral part of the Polish Basin, strongly influenced by inversion tectonics and fed by transverse and parallel depositional systems. The study area is located in northern Poland, in the boundary zone between the southeastern marginal part of the East European Craton and the northeastern margin of the Mid-Polish Anticlinorium, a regional inversion structure that runs northwest-southeast across the entirety of Poland. Traditionally, a “layer-cake” geological model, mainly based on borehole data, has been employed to characterize the regional depositional architecture of the Upper Cretaceous succession. Our new interpretation is based on regional geo-seismic transects, including the unique, regional high-resolution PolandSPAN™ seismic survey, calibrated by deep wells. The upper Albian – Upper Cretaceous succession was subdivided into five regional seismic stratigraphic units. Within these units, seismic facies and corresponding lithofacies representing siliciclastic and carbonate-siliceous depositional systems are described. The relative role of transverse and parallel depositional systems, including bottom currents, was recognized. Bottom current activity was documented by numerous, previously unknown seismostratigraphic features such as changes in lateral thickness, unconformities, and incisions. Two recognized contour current systems (N–S and NW–SE) operated along the edges of inversion structures that were uplifted in the Late Cretaceous – Palaeogene. A very significant rearrangement of this part of the Polish Basin, highlighted by a regional unconformity mappable over the entire study area, took place in the Campanian – Maastrichtian.