On the origin of chloride waters in the Polish Flysch Carpathians

Chloride waters in the Polish Flysch Carpathians are remnants of marine sedimentation water which was chemically and isotopically changed due to ultrafiltration and the release of dehydration water (diagenetic water) during the burial diagenesis of clay minerals. In the western part of the study area, the diagenetic end-member is characterized by δ18O and δ2H values of about +6.5 and –30.0‰, respectively, and Cl– content in the range of 3.8 and 13.8 g/dm3. In some fault areas, such waters migrate to the surface and mix with local meteoric waters as indicated by mixing lines in δ18O–δ2H and δ18O–Cl– graphs. In several wells of the eastern part, waters containing a significant proportion of marine water occur. However, in majority of deep wells, mixtures of diagenetic and meteoric waters of Quaternary and pre-Quaternary climates are present, as deduced from δ18O–Cl– linear relations. In most cases, they do not exhibit linear relations also expected in δ18O–δ2H graphs due to the shifts of δ2H to heavier isotopic values supposedly caused by involvement of water in the generation of hydrocarbons.