9319605 Fehn This project is a continuation of the Principal Investigator's work on the determination of cosmogenic isotopes in fluids from the KTB deep drill hole in Germany. Initial results suggest that 36 Cl/Cl ratios in waters collected from the pilot hole and from the main borehole reflect the subsurface production of these isotopes. The results can therefore be used for the determination of residence times and source formations of these waters. The Principal Investigator has made good progress with modest initial funding to demonstrate the feasibility of using the chlorine isotope systematics to determine the residence times and sources of deep fluids found in the KTB boreholes. The results of this project should lead to a much better understanding of fluid flow, origin, and residence time of deep crustal fluids. ***
