The impact of melt versus mechanical wear on the formation of pseudotachylyte veins in accretionary complexes.

Whether seismic rupture propagates over large distances to generate mega-earthquakes or is rapidly aborted mainly depends on the slip processes within the fault core, including particularly frictional melting or intense grain-size reduction and amorphization. The record of seismic slip in exhumed fault zones consists in many instances in Black Faults Rocks, dark and glass-like-filled aphanitic veins that have been interpreted as resulting from the quenching of frictional melts, i.e.

High-pressure, High-temperature Deformation Experiment Using the New Generation Griggs-type Apparatus.

In order to address geological processes at great depths, rock deformation should ideally be tested at high pressure (> 0.5 GPa) and high temperature (> 300 °C). However, because of the low stress resolution of current solid-pressure-medium apparatuses, high-resolution measurements are today restricted to low-pressure deformation experiments in the gas-pressure-medium apparatus.

On the conditions of magma mixing and its bearing on andesite production in the crust.

Mixing between magmas is thought to affect a variety of processes, from the growth of continental crust to the triggering of volcanic eruptions, but its thermophysical viability remains unclear. Here, by using high-pressure mixing experiments and thermal calculations, we show that hybridization during single-intrusive events requires injection of high proportions of the replenishing magma during short periods, producing magmas with 55-58 wt% SiO2 when the mafic end-member is basaltic. High strain rates and gas-rich conditions may produce more felsic hybrids.