title: Pleistocene age paleo-groundwater inferred from water-stable isotope values in the central part of the Baltic Artesian Basin.
abstract: A new data set of δ(2)H and δ(18)O in the groundwater from the central part of the Baltic Artesian Basin is presented. The hydrogeological section is subdivided into stagnation, slow exchange and active exchange zones. Na-Ca-Cl brine found at the deepest part - the stagnation zone - is characterized by δ(18)O values above -5 ‰ and δ(2)H values approaching -40 ‰ with respect to Vienna Standard Mean Ocean Water. The slow exchange zone where waters of mostly intermediate salinity reside is characterized by δ(18)O values around -11.7 ‰ and δ(2)H values around -85.3 ‰. Mean δ(18)O and δ(2)H values of the fresh groundwater in the active water exchange zone are -11.1 and -79.9 ‰, respectively. Characteristically, the groundwater in the active and slow exchange zone is isotopically more depleted compared with the precipitation values observed, and the depletion increases with depth down to the level where strongly enriched brines are encountered.
authors.affiliation: a Centre of Geological Processes Research and Modelling, Department of Geology , University of Latvia , Riga , Latvia.
authors.forename: Alise
authors.initials: A
authors.lastname: Babre
authors.affiliation: b Institute of Ecology and Earth Sciences, Department of Geology , University of Tartu , Tartu , Estonia.
authors.forename: Andis
authors.initials: A
authors.lastname: Kalvāns
authors.affiliation: a Centre of Geological Processes Research and Modelling, Department of Geology , University of Latvia , Riga , Latvia.
authors.forename: Konrāds
authors.initials: K
authors.lastname: Popovs
authors.affiliation: a Centre of Geological Processes Research and Modelling, Department of Geology , University of Latvia , Riga , Latvia.
authors.forename: Inga
authors.initials: I
authors.lastname: Retiķe
authors.affiliation: a Centre of Geological Processes Research and Modelling, Department of Geology , University of Latvia , Riga , Latvia.
authors.forename: Aija
authors.initials: A
authors.lastname: Dēliņa
authors.affiliation: c Institute of Geology , Tallinn University of Technology , Tallinn , Estonia.
authors.forename: Rein
authors.initials: R
authors.lastname: Vaikmäe
authors.affiliation: c Institute of Geology , Tallinn University of Technology , Tallinn , Estonia.
authors.forename: Tõnu
authors.initials: T
authors.lastname: Martma
mesh_terms: D003903:Deuterium / Q000032:analysis*; D060587:Groundwater / Q000737:chemistry*; D010103:Oxygen Isotopes / Q000032:analysis*
chemical_list: D010103:Oxygen Isotopes; D003903:Deuterium
keywords: Baltic Artesian Basin; Latvia; brines; d-excess; groundwater development; hydrogen-2; isotope hydrology; oxygen-18; palaeohydrogeology