Delineation of deformation grades of low-strain granitoids using assemblages of elementary deformation textures

Proceedings of the International workshop on the Nojima Fault core and borehole data analysis

“…The veins have not been studied in detail because only horizontal thin sections were available and it was not yet possible to decipher precisely the kinematics of these structures. Biotite crystals display kink-bands (Figure I) similar to those described by Kosaka et al (1999). They indicate, first, the direction of shortening and, second, the finite strain (Figure 2).…”

“…Except in the immediate vicinity of the fault, quartz crystals scarcely exhibit classical features of plastic (intracrystalline) deformation such as undulose extinction, subgrains, dynamic recrystallisation (see Kosaka et al, 1999). On the contrary, quartz crystals are intensely fractured and several types of structures may be distinguished: (i) Fluid inclusion planes are mode I fractures which have been healed by dissolution-crystallisation processes (Tuttle.…”

Geoquímica e geocronologia do granitóide Barra Alegre, faixa móvel Ribeira, Rio de Janeiro

“…As lamelas de biotita apresentam contatos serrilhados e dobras suaves e por vezes estão em junção tríplice com grãos de quartzo e plagioclásio. Kosaka et al (1999) apontam que tais efeitos de deformação em grãos de quartzo, plagioclásio e biotita podem ser gerados tanto a partir de esforços no estado sólido, como durante a cristalização de líquidos graníticos, quando o magma se comporta como mush. A microclina mostra típica geminação "tartan", com poucas lamelas pertí-ticas, estando eventualmente bastante sericitizada e caulinizada.…”