Geoscientist Dominik Sorger has been following a literally hot lead. As part of an international research team led by the University of Göttingen, he examined a rock from Papua New Guinea which, around 4.4 million years ago, was carried to a depth of more than 90 km by subduction – the downward movement of a tectonic plate – and later returned to the surface. Tiny inclusions in garnet crystals show that, during the first part of its journey, this rock was significantly warmer than had previously been assumed.
“Such inclusions are a rare stroke of luck, as rocks from such great depths rarely preserve information about earlier stages of their subduction. It is precisely these that reveal new insights into the evolution of pressure and temperature in subduction zones,” reports Sorger. This surprising finding may help us to better understand the effects of subduction processes on earthquakes and volcanic activity.
Publication:
Geothermal gradient change during subduction recorded by ultrahigh-pressure eclogite, Schönig et al., Nature Geoscience (Open Access), DOI: https://doi.org/10.1038/s41561-026-02110-1
