Fig. 3

Map of the Grimsel Breccia Fault zone, its mineralisation and geological environment. Positions A–F, Grimsel Shear Zones (GSZ) 1–3, the Southern Boundary Shear Zone (SB SZ) and line intercept traces SD 1–3 are referred to in the text. The tectonic foliation is steeply dipping (>70°) throughout the study area. Shear zone/fault plane dips are indicated along traces. Mineralised outcrops are defined by ubiquitous mineralised fractures and void space. Mineralisation extent traces the outline of the mineralised outcrops as well as discreet traces of mineralisation too small to represent here. Lines are dashed where inferred. See text for further methodology. All altitudes in metres above sea level. Lithologies are modified after Stalder (1964), Abrecht (1994), and Wehrens (2015) and major SZs are drawn after Baumberger (2015) and Wehrens (2015)