Conditions and duration of high temperature metamorphism in large hot orogens assessed through petrochronology : insights from grenville tectonics
Deciphering duration and conditions of metamorphism in orogenic systems is crucial to understand large-scale tectonic processes. In the last decades, the development of thermodynamic modeling and instrumental advances in elemental and isotopic analysis have open new avenues to unravel the Pressure-Temperature-time paths of rocks, to assess the rates and duration of large-scale orogenic processes. However, orogenic roots in Large Hot Orogens (LHOs) that can attain and maintain temperatures higher than 800°C over several tens of million years still challenge our ability to decode the timing of events, and our understanding of tectonic processes and crustal evolution.
CHRONOTEC proposes an innovative multi-approach strategy using state-of-the-art instrumentation, to link the chronometers garnet and zircon through their isotopic (U-Pb in zircon; Lu-Hf and Sm-Nd in garnet, O in garnet and zircon) and elemental (trace element) record, combined to a detailed petrological investigation, including phase diagram modeling. This approach will be systematically used on selected mafic granulites from distinct crustal levels (mid and high pressure) of the Central Grenville Province in Canada, one of the first LHOs on Earth. CHRONOTEC will bring a complete portfolio of new fundamental results from natural samples to assess the link between zircon and garnet in high-T mafic rocks. Integration of the results will provide an unparalleled framework to assess the metamorphic evolution of the central Grenville province, and by comparison to other LHOs, will refine our understanding of large-scale high-T orogenic processes.