Ultramilonitas de apariencia fluidal, pseudotaquilitas o algo intermedio? (Formación Bacariza, Cabo Ortegal)

Abstract

Occurrence of tectonites with features characteristic of both pseudotachylytes and ultramylonites formed under high-pressure granulite-facies conditions is reported in the Cabo Ortegal Complex of NW Spain. We interpret that these rocks were originated due to a seismic event at great depth (1.4 GPa) under high temperatures (740 ºC). Shear heating would have affected the still hot and mechanically rigid granulites and provoked melt formation. Ambient high P and T would have led to subsequent recrystallization of the previously formed melt giving rise to a weak planar fabric