Current applications using key mineral phases in igneous and metamorphic geology: perspectives for the future

Abstract

The study of magmatic and metamorphic processes is challenged by geological complexities like geochemical variations, geochronological uncertainties and the presence/absence of fluids and/or melts. However, by integrating petrographic and microstructural studies with geochronology, geochemistry and phase equilibrium diagram investigations of different key mineral phases, it is possible to reconstruct insightful pressure-temperature-deformation-time histories. Using multiple geochronometers in a rock can provide a detailed temporal account of its evolution, as these geological clocks have different closure temperatures. Given the continuous improvement of existing and new in situ analytical techniques, this contribution provides an overview of frequently utilized petrochronometers such as garnet, zircon, titanite, allanite, rutile, monazite/xenotime and apatite, by describing the geological record that each mineral can retain and explaining how to retrieve this information. These key minerals were chosen as they provide reliable age information in a variety of rock types and, when coupled with their trace element (TE) composition, form powerful tools to investigate crustal processes at different scales. This review recommends best applications for each petrochronometer, highlights limitations to be aware of and discusses future perspectives. Finally, this contribution underscores the importance of integrating information retrieved by multi-petrochronometer studies to gain an in-depth understanding of complex thermal and deformation crustal processes.