Transcurrent Shear Zones and Magma Emplacement in Neoproterozoic Belts of Brazil

Abstract

The association of shear zones and magmatism is usually regarded as indicating that partial melting and/or melt transport and emplacement was favored by pre-existing shear zones. However, a detailed examination of a set of examples from Neoproterozoic belts of Brazil allows us to suggest that this interpretation is not unequivocal. In some cases, for instance dyke-swarms, dyke-like plutons and small elongated plutons, a large body of evidence supports shear zone-assisted melt emplacement. In other instances, and especially for large-scale plutons, demonstrative criteria for shear zones predating magma emplacement are lacking, or even support magma emplacement predating shear zone development. Either pluton-enhanced strain localization and shear zone nucleation, or coeval growth of shear zone and granite emplacement, may represent alternative processes resulting in a close association of shear zones and plutons.KeywordsShear ZoneMagma ChamberCountry RockDyke SwarmMylonitic FoliationThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.