Fig. 10

Conceptual model of the structures and fluid pathways at Grimsel Pass. The top surface is cut through the 3D model at 2700 m a.s.l. and the vertical and horizontal scales are equal. Structures south of the GBF are stripped away. Sub-vertically oriented, ‘pipe’-like up-flow zones, in the Sidelhorn Linkage Zone and Grimsel Pass-Gletsch Zone are indicated. Hydraulic constraints are annotated after Pfeifer et al. (1992) and Hofmann et al. (2004). Possible fluid infiltration and migration pathways are indicated: (1) Directly down the GBF, either side of up-flow zones. (2) Lateral migration along GBF. (3) Through the regional SZ network, including NW–SE oriented faults that may intersect the GBF and its host SZs at depth