Abstract: Slow slip and tremor (SST) in subduction zones occurs over an incredible range of Pressure-Temperature conditions, but one common denominator is the presence of metamorphosed oceanic crust containing amphibole as a strain-accommodating phase. However, the rheology of amphibole is poorly constrained, so its contribution to steady-state strength and/or slip transients is unknown. I will compare natural amphibole microstructures from three exhumed subduction complexes that record hot, warm, and cold subduction geotherms, spanning a P-T range that encompasses observed SST in active margins, and discuss the deformation conditions and mechanisms that may produce transients. Using nanoindentation experiments, I will then provide new insight into low-temperature plasticity in glaucophane, to discuss the implications of dislocation-accommodated deformation in cold shear zones. Depending on temperature, the presence/distribution of other phases, and fluid content, amphibole may be capable of accommodating steady-state flow and/or deformation transients over the range of observed SST depths.
You will find the complete schedule for Njord Seminar Series fall '22 here.
To get news, invitations to seminars and more from Njord, please go here to subscribe to our newsletter.