[en] A study of 80 noble gas samples from the aquifer overlying the salt dome of Gorleben (Germany) revealed noble gas temperatures (NGTs) between +12 deg. C and -12.7 deg. C. Duplicate samples showed the same results (± 1 deg. C) and samples from the shallower part of the aquifer showed NGTs of the mean annual soil temperature (8 deg.C.). Since It is impossible to interpret the negative NGTs (11 wells) in terms of the mean annual infiltration temperature, an excess of up to 30% in the concentration of the noble gases requires an explanation. This effect was not yet observed in noble gas palaeotemperature measurements. The salt dome - its top lying -250 m mean see level (m.s.l.) - is directly overlaid by an aquifer with high permeability and highly saline water (up to 330 g/L NaCl). A layer with low permeability (-70 to -170 m m.s.l.) separates this saline water from the shallow fresh water (+20 to -70 m m.s.l.). The latter flows in an aquifer with high permeability and the NGTs are similar to the contemporary mean annual soil temperature. Nearly all samples with apparent negative NGTs stem from the low permeability layer in an area directly above the salt dome. Numerical modelling of salt induced diffusion and of transport for the coupled system of noble gases and salt shows that the negative noble gas temperatures can be explained by a loss of noble gases from the highly saline aquifer: since salt drastically reduces the noble gas solubilities, the brines are supersaturated with respect to the noble gases. This supersaturation is the driving force enriching the low permeability layer above the brines with noble gases and causing apparent negative NGTs. Therefore, in palaeoclimatic studies using the noble gas thermometer, care has to be taken that high salt concentrations do not disturb the palaeotemperature information of the noble gases in inhomogeneous aquifers. (author). 13 refs, 9 figs