Garnet Lu–Hf and Sm–Nd geochronology: a time capsule of the metamorphic evolution of orogenic belts

Abstract

AbstractGarnet has played a crucially important part in our understanding of metamorphic and tectonic processes and conditions. Technological advances in chemical procedures and mass spectrometry have allowed precise determinations of the Nd–Hf isotope composition of small samples, which has boosted the growth of Lu–Hf and Sm–Nd geochronology over the last two decades. When combined with petrographic and chemical observations, Lu–Hf and Sm–Nd ages in garnets are able to give unprecedented resolution of the timing and processes of metamorphism, although there are many potential pitfalls in the acquisition and interpretation of these data. This paper provides a brief review of the basic science and development of the garnet Lu–Hf and Sm–Nd systems, highlights the potential of garnet Lu–Hf and Sm–Nd geochronology, and reviews several crucial issues related to the complexities of interpretation of the radiometric ages. A case study using combined garnet Lu–Hf and Sm–Nd dates for a garnet-bearing granitic gneiss from the Dabie orogenic belt is presented.