Geologic history written in garnet sand

Garnet sand beach on Goodenough Island, Papua New Guinea. The garnets originate from rocks such as 'gneiss' (a type of metamorphic rock formed by high-temperature and high-pressure), and are then deposited on the beach as grains of sand. Photo: Paul Fitzgerald Research team with participation from Göttingen University use secrets trapped in grains of sand to reveal rock journey and formation On a remote island in Papua New Guinea, an international research team including the University of Göttingen has made an important geological discovery from a garnet-rich sand. By analysing tiny -inclusions- (minerals trapped inside another mineral during its formation) in the garnet grains, they gained understanding of the recycling pathway from the surface of the Earth to deep within the upper mantle and back to the surface, due to tectonic and sedimentary processes. This cycle happens in less than around 10 million years, which for such geologic processes is a remarkably short time. The results were published in the Proceedings of the National Academy of Sciences (PNAS). The study was conducted in a tectonically active boundary zone in Papua New Guinea, where converging tectonic plates slide toward each other with one plate moving underneath the other.