Metamorphic transformation rate over large spatial and temporal scales constrained by geophysical data and coupled modelling

Metamorphic transformation rates are classically determined on decimetre-scale field samples and from laboratory experiments at smaller scales. Here we present a geophysical approach based data joint geophysical–petrological modelling to quantify the average rate of metamorphic transformations 10–100-kilometre million-year The model simulates eclogitization Indian lower crust as it penetrates beneath southern Tibet. is tracked by its densification, effect which then compared observed gravity anomalies. From find that crust's overall densification requires partially hydrated initial composition. Moreover, modelled evolution this what predicted pressure–temperature–density grids consistent with delayed, far-from-equilibrium metamorphism. descends underneath Himalaya until Tibet in thermodynamically metastable state first dehydration reactions reached. This observation used determine rock an eclogite facies assemblage, constrained between ~6 × 10?9 5 10?7 g/cm2/year, reaction affinity 0.8–1.6 kJ/mol oxygen. Compared data, range results matches effective typically associated regional fit correlation across scales legitimates use small large-scale geodynamic studies.