Disposal of highly radioactive nuclear waste in crystalline bedrock − geological setting of the investigation areas in Finland and Sweden
Leaders: Michael Stephens, Jussi Mattila, Seppo Paulamäki and Carl-Henric Wahlgren
Summary: An excursion is planned to three areas in the crystalline bedrock of Finland and Sweden, which have been investigated in connection with the planned disposal of highly radioactive nuclear waste at a depth of c. 400-500 m. The excursion will involve visits to key outcrops and trenches at the surface, a study of cored boreholes and a visit to two underground facilities. The areas are situated in contrasting tectonic segments in the central and southern parts of the Fennoscandian Shield, which forms one of planet Earth´s ancient continental nuclei. The bedrock in these segments formed along a continental margin, which was tectonically active during the time interval 1.96−1.75 Ga, and was subsequently affected by brittle deformation at least after c. 1.70 Ga. With the help of unique, high-resolution surface and sub-surface data, the excursion will focus attention on the tectonic evolution within each segment and, thereby, provide a key insight into geological developments in these parts of the shield.