Tracing groundwater from uranium rich environments by Cl-36 isotope method: possibilities for natural analogue studies

Abstract

Using 36Cl dissolved in groundwater as a monitor of subsurface neutron fluxes makes it possible to obtain information on the composition of the rocks interacting with the groundwater flow. In particular, the concentrations of uranium and thorium can be evaluated, which are dominant source of subsurface neutrons. This can provide information in connection with exploration of uranium ore deposits. Based on the results of several case studies from aquifers in crystalline rocks with moderate to high uranium contents, it is demonstrated that groundwater especially from uranium ore deposits shows characteristic 36Cl concentrations which are high above today's levels of atmospheric precipitation even for young groundwater of short residence times.