Fig. 2
a Stereographic projection of planes and their poles of subvertical Alpine fissure in the Western Alps. Localities are indicated in Fig. 1. Fissures in high pressure regions and in the Argentera Massif are presented in b-f and g-h, respectively. b NNE (N020) striking vertical fissure in amphibolite facies metabasalt of the Zermatt-Saas high-pressure zone. At the locality of Mittaghorn, Saas Fee, Switzerland, the vertical fissure shown contains crystals of albite (pericline), quartz and chlorite (the wall of the fissure is indicated by the blue arrow). c Subvertical, SSE (N145) striking fissure in Permo-Carboniferous metaconglomerates at Montvalezan, Savoie, France (yellow-dashed lines), associated with strike-slip faulting (note horizontal lineation). The fissure is located in greenschist-facies overprinted blueschist facies rocks. d N (N000) striking, subvertical fissures (green-dashed lines) in greenschist facies overprinted eclogite facies metasedimentary rocks at Margone, Val di Viù, Piedmont, Italy. Sample VIU1 is from this locality. e Meta-granitoid rocks at Montoso, Piedmont, exploited as "Pietra di Luserna". The steeply oriented, NE (N050) striking fissures (indicated by red-dashed lines) cutting the horizontal foliation caused bleaching (dissolution of biotite) in the adjacent host rock. Fissure monazite was reported from these quarries (Finello et al. 2007). f Permian metarhyolites and metasedimentary rocks forming the mountains of Costa Balzi Rossi, Magliolo, Liguria, Italy. The dated monazite sample BALZI1 derives from fissures located in the wall-forming metarhyolites (Bracco et al. 2012), but was collected in the scree. g Vertical N-S (N005) striking fissures (indicated by orange-dashed lines) at the locality Sambuco, Valle Stura, Argentera Massif. Monazite is reported from fissures of this area. Monazites from Vinadio (VINA1) and Moriglione (MORI1) in Valle Stura are from comparable fissures. h NNE (N020) striking fissure in metamorphic Permian siltstones of the Argentera Massif, France, ca. 1.5 km north of Saint-Dalmas de Tende, showing milky quartz crystals on fissure wall (violet arrow).