Latent magmatism beneath the Korean Peninsula caused by asthenosphere upwelling

Volatiles such as helium and carbon dioxide provide insights into geological processes spanning from the Earth’s deep interior to its surface. Integration with geophysical data providing enhanced vertical resolution with a wider horizontal range better elucidates the mantle dynamics and its interactions with the crust. Here we present geochemistry of volatiles dissolved in fluid samples from fault-related springs, thermal spa waters, and groundwaters across the Korean Peninsula. These were examined in conjunction with existing geophysical information. Remarkably, there is a strong spatial correlation between helium isotopes and S-wave velocity, suggesting the influence of mantle upwelling on both geochemical and geophysical parameters. Furthermore, the computed helium flux is comparable to that of volcanic regions, implying partial melting induced by mantle upwelling due to edge-driven convection beneath the Korean Peninsula. Therefore, these findings suggest that mantle-derived volatiles can be released diffusely over large areas through faults in the modern Earth’s intraplate environment. The geochemical signature of mantle upwelling-induced magmatism is observable in groundwater on the Korean Peninsula, according to geochemical data of volatiles from fault-related fluids combined with three-dimensional seismic tomography.