Heidelberg 2015 – scientific programme

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UP: Fachverband Umweltphysik

UP 13: Postersession Bodenkunde, Kryosphäre, Meßtechnik, Ozeanographie

UP 13.24: Poster

Thursday, March 26, 2015, 10:45–19:45, G/Foyer

Noble Gases of Glacial Origin in Palaeogroundwater in the Northern Part of the Baltic Artesian Basin, Estonia. — •Therese Weissbach¹, Werner Aeschabch-Hertig¹, Valle Raidla², and Rein Vaikmäe² — ¹Institute of Environmental Physics, Heidelberg University, Heidelberg, Germany — ²Institute of Geology, Tallinn University of Technology, Tallinn, Estonia

The Cambrian-Vendian (Cm-V) and Ordovician-Cambrian (O-Cm) aquifer systems are part of the Baltic Artesian Basin (BAB). The groundwater of these aquifer systems is characterized by a strong depletion of the stable isotope composition (δ¹⁸O in the range of -18.5to -22) and low radiocarbon concentration. Considering both facts, an origin of this groundwater from glacial meltwater during the last glaciation is indicated. An extensive noble gas study was conducted in these aquifer systems to investigate the noble gas signature of this water, which is known to be unusually gas rich. Indeed, the BAB groundwaters exhibit enormous excess air amounts, which could be due to trapped air in glacial ice that was forced into solution during recharge beneath an ice sheet. Furthermore, the noble gas composition of the Estonian wells clearly shows a depletion of neon compared to atmospheric air, possibly due to a loss of neon by diffusion through the ice. However, no conclusive scenario for the formation of the highly unusual noble gas signature is currently available.