Heidelberg 2015 – wissenschaftliches Programm
UP 13.24: Poster
Donnerstag, 26. März 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.