Benedito C. Rodrigues

Ductile shear zones

European Union through the European Regional Development Fund, based on COMPETE 2020 (Programa Operacional da Competitividade e Internacionalizacao), project ICT (UID/GEO/04683/ 2013) with reference POCI-01-0145-FEDER-007690 and national funds provided by Fundacao para a Ciencia e a Tecnologia.“Tabular or sheetlike, planar or curviplanar zones in which rocks are more highly strained than rocks adjacent to the zone” are called ductile shear zones. Identification and study of ductile shear zones are important since major plate boundaries are defined by such shear zones. We need to study such zones since along them partially molten rocks can flow. Secondly, viscous dissipation related to such zones has been investigated. The ductile shear sense/sense of movement from such zones can be deciphered mainly from asymmetric sigmoid, parallelogram and lenticular clasts and intrafolial folds. See Passchier and Trouw for review on ductile shear zones. In addition to such shear sense indicators, this chapter also presents near-symmetric clasts that form possibly within shear zones but that do not give the shear sense.