Historia rozwoju geologicznego Kujaw

Abstract

HISTORY OF GEOLOGICAL DEVELOPMENT OF THE KUJAWY REGIONSummaryThe Kujawy region is situated within the western marginal area of the Precambrian platform and is separated from this latter by the zone of Teisseyre's line that makes a framework of the Caledonian geosyncline. East of the zone of Teisseyre's line the rocks of the youngest Precambrian (Wendian) and of the Cambro-Silurian developed under epicontinental conditions, whereas west of this zone – under geosynclinals ones.Both uplifting and additional folding of the Caledonian chain took place after the Gedinnian time. On the slopes and in the lowered areas Old Red molasse accumulated. At the Siegenian-Emsian boundary, the marine invasion entered the still not base-levelled area. From the Middle Devonian sea some fragments of the Caledonian rock massif emerged. The sedimentary equalization took place only at the Frasnian time, when the carbonate facies, dominating in this area, stabilized.At the Tournaisian mainly, however, at the Lower Visean time, the block movements of the Bretonian phase, accompanied by volcanic activity, led to a withdrawal of the sea.Transgression began at the Middle Visean time, and the total sea invasion started in the Upper Visean. Deposits of that time are developed in Culm facies, or in paralic facies that generally dominated at the Namurian time, and proceeded still during the Westphalian A. The deposits of Westphalian B, C, and D are developed in limnic, at places also in productive facies.The uplifting of the Sudetic Variscides and of the Moravo-Silesides during the Asturian and Saalian phases was responsible for the formation of a foredeep that comprised also the Kujawy Region. The foredeep was then filled in with the thick Upper Carboniferous and Lower Permian, deposits. These processes were accompanied by volcanic activity.The peneplanation of the Variscides and the infilling of the foredeep prepared the lowland area for the Zechstein sea transgression. Both the Kujawy Region and the adjacent zones were an area of the strongest subsidence at the Zechstein time and then, posthumously, in the Mesozoic. The greatest subsidence tendencies were conditioned by some deep-seated discontinuity zones in the basement.Some common vertical movements of the basement blocks developed at the boundary of the Middle and Upper Muschelkalk; at its close they were responsible for a marine regression.At the Keuper time, the Kujawy basin changed into an isolated one, where brackish and, later on, limnic sedimentation prevailed. The increased mobility of the individual blocks of the basement caused the displacement and the first piercements of salt masses, particularly at the Keuper–Rhaetic boundary.At the Lower Jurassic time, the limnic sedimentation was being frequently broken by several slight sea ingressions that took place in the Lower Hettangian, Lower Sinemurian, Pliensbachian and Lower Toarcian.At the Aalenian time, a sea ingression took place, and in the Middle and Upper Jurassic it ruled over the entire Lowland basin. At that time, the Middle Jurassic basin was characterized by some short-lived transgressive oscillations that resulted in the changes of bath lithofacies and local symsedimentary washout of the deposits.At the Upper Callovian and the lowermost Oxfordian times, the basin became shallow. During the Middle and Upper Oxfordian times, the sedimentary conditions (i.e. carbonate lithofacies) were already uniform. In the Kimmeridgian and Portlandian, the carbonate lithofacies gave way to the calcareous-marly one, whereas in the Upper Portlandian, the epeirogenic movements led to the regression of the Jurassic sea.The recurrence of the marine transgression was at the Berriasian time. In the Lower Cretaceous, a swallowing of the basin, resulting in the formation of arenaceous deposits, found their full development at the Middle Valanginian time, partly also at the Upper Hauterivian and the Berriasian – Middle Albian times. At first, an arenaceous – glauconite – carbonate lithafacies developed, changing then into a marly – carbonate one. After the Lower Maastrichtian time, the Middle Polish swell and the adjacent Szczecin trough, Mogilno-Łódź trough, and Miechów trough were uplifted. Salt plugs broke through the overlying strata to the surface, and so a general structural reconstruction of the Zechstein – Mesozoic rock complex terminated