Deep crustal embrittlement and fluid flow during granulite metamorphism in the Limpopo Belt, South Africa

Deep crustal rocks generally deformed in a ductile manner and have a very low permeability. However, in the Southern Marginal Zone of the Limpopo Belt solutions/fluids have moved through high-grade rocks and reacted with these on a regional scale along a major shear zone. Strike-slip environments there have more widespread alteration than thrust-fault environments. Under high-grade metamorphic conditions, brittle failure and hydraulic fracture processes, in particular, have occurred in these deep crustal rocks. The latter phenomenon provides a mechanism for developing permeability and plumbing systems for the migration of fluids and/or liquids through the deep crust. -from Authors