HR: 1340h
AN: H23F-1494    [Abstracts]
TI: Out-Diffusion Technique for Characterizing Pore Fluids in Crystalline Rocks
AU: * Lambie, K E
EM: kelambie@scimail.uwaterloo.ca
AF: University of Waterloo, 200 University Ave W, Waterloo, ON N2L 3G1 Canada
AU: Frape, S K
EM: shaun@sciborg.uwaterloo.ca
AF: University of Waterloo, 200 University Ave W, Waterloo, ON N2L 3G1 Canada
AU: Hobbs, M
EM: monique.hobbs@opg.com
AF: Ontario Power Generation, 700 University, Toronto, ON M5G 1X6 Canada
AU: Gascoyne, M
EM: gascoyne@granite.mb.ca
AF: Gascoyne GeoProjects Inc.(GGP), PO Box 141, Pinawa, MB R0E 1L0 Canada
AB: Crystalline shield rock has been identified as a possible disposal medium for high level radioactive waste in several international research programs, including the Finnish, Swedish and Canadian programs. At depth within the crystalline environment, groundwaters are found to be saline, likely as a result of long-term water-rock interactions. Characterization of waters within the connected pore space of the rock (or the matrix pore fluid) is important, because this water would be available to interact with containment systems within a repository. The purpose of this research is to evaluate an out-diffusion technique for determining matrix pore fluid compositions using rock core from two new boreholes drilled at the Underground Research Laboratory located in Manitoba, Canada. In the experiments, rock core is submerged in doubly-deionized water, and the diffusion of chloride out of the core is monitored with time to determine when the system has reached steady-state. Once steady-state has been reached, the final solution composition is analyzed for major elements. The preliminary results from five different cores show that Cl-concentrations approached steady-state at variable rates, with each of the five experiments reaching a different peak concentration, despite the close proximity of the core sections examined. These findings agree with results of a previous study on the Žspo granites, Sweden, which have been interpreted to represent significant variations in matrix pore fluid compositions over distances of a few meters within the same rock mass.
DE: 0702 Permafrost (0475)
DE: 1099 General or miscellaneous
SC: Hydrology [H]
MN: Fall Meeting 2005