The effects of quartz recrystallization and reaction on weak phase interconnection, strain localization and evolution of microstructure

摘要: Abstract We conducted axial compression and general shear experiments, at T = 900 °C P = 1.5 GPa, on samples of banded iron formation (BIF) synthetic aggregates quartz, hematite magnetite to investigate how dynamic recrystallization quartz promotes strain localization, the role weak second phases (oxides) rheology microstructural evolution aggregates. Experiments showed localization into oxide rich layers, that content distribution are key factors for strength aggregate. Only 2–10 wt.% leads pronounced weakening increasing above ∼10% has only a minor additional effect. Where grains dispersed, initial contrast with induces stress concentrations their tips, promoting high recrystallization-accommodated dislocation creep quartz. Fine recrystallized reacts oxide, forming trails fine reaction product (ferrosilite/fayalite) leading interconnection/percolation weaker matrix. The between framework these fine-grained micro-shear zones, inducing drastic weakening. Thus syn-deformational reactions microstructurally-controlled phase contrast. It results in rheologic transition from load-bearing matrix-controlled rheology, S–C′ S–C fabric strain.