Fig. 4
From: Criteria and geological setting for the generic geothermal underground research laboratory, GEOLAB
EPS1 core K195 at 2156 m depth (top) showing the zonation of an altered fault. Two consecutive horizontal lines represent 20 cm. A quartz vein is often sealing the centre of a fracture and is surrounded by an alteration halo, characterised by an assemblage of secondary minerals formed during hydrothermal alteration. The adjacent brecciated and cataclased zones are highly porous and permeable zones (Meller et al. 2014)