Hydrogeological evolution of the Upper Cretaceous artesian basin of the Gdańsk region

Abstract

Hydrogeologiczny rozwój gdańskiego górnokredowego basenu artezyjnskiego The hydrogeological conditions of the artesian basin of the Gdańsk area are presented basing on the palaeohydrogeological studies. There were three successive hydrogeological cycles in the geological history of the analysed structure: the first - Albian to Montian, the second - Late Eocene to Early Miocene, and the third - Miocene up to the present. Each cycle consisted of a sedimentary stage with an elision hydrodynamic system and of an infiltrational one with a gravitational hydrodynamic system prevailing. The evolution of the groundwater chemistry is considered; especially the changes of a Cl -Na type of water of marine origin into meteoric groundwater of HCO3 -Na-Ca type. A number of geological processes which occurred in the basin in the past directly influence the present hydrodynamical conditions of the Cretaceous waterbearing strata.