The timing of extreme metamorphism

Classical petrological and geochemical tools provide only limited insights into extreme metamorphism because fast diffusion of major elements and annealing effectively eliminate crucial information.We are developing new and innovative tools for high-resolution investigation of partial melting and high-grade metamorphism based on recent findings that some trace elements, due to their slower diffusion, are the most retentive record of metamorphic processes.

Additionally, trace elements permit a direct link between datable accessory minerals and metamorphic conditions. Our results show that extreme metamorphic conditions can last from few million years such as the case of fast subduction and fast exhumation of diamond-bearing gneisses to tens of millions of years in slowly cooling granulite-facies terrains.