Dehydration-induced supralithostatic fluid overpressure in metapelites from Northern Korea

Orogenic reconstructions typically assume lithostatic pressure, which can be converted into burial depth. Deviations from lithostatic conditions, such as fluid overpressure, are recognized but poorly understood in natural rocks. Here we integrate petrological analysis, radiometric dating, and diffusion chronology to explore the thermal overprinting on metapelites from a Precambrian orogen caused by ca. 110 Ma porphyritic intrusions in Northern Korea. The dissolution-reprecipitation textures of garnet and monazite from the metapelites reveal rapid heating, dehydration, and reworking within ~300 years, reaching 600‒640 °C and 0.75‒0.85 GPa at ca. 110 Ma. The barometric results indicate depths that, if lithostatic, sharply contrast with the shallow emplacement of the contemporaneous porphyries nearby, indicating dehydration-induced supralithostatic fluid overpressure. These findings challenge the lithostatic paradigm and suggest that rapid dehydration and deviation from lithostatic pressures may be more prevalent than previously recognized, with important implications for orogenic reconstructions and seismogenic behaviors at plate boundaries. Rapid dehydration and garnet growth can induce supralithostatic fluid overpressure with important implications for tectonic reconstructions and seismic behaviors, according to thermobarometry and geochronology data from Proterozoic metapelites from Northern Korea.