Continuous nonthermal slab gap formed by progressive tearing <bold>beneath Northeast Asia</bold>

초록

Slab gaps in subducted plates are widely hypothesized to channel hot mantle upwellings, yet their formation and thermal state remain enigmatic. Here we image a continuous similar to 1000 km-long arcuate slab gap in the mantle transition zone beneath Northeast Asia with no evidence of anomalous heat. By integrating dense-array teleseismic tomography, 3-D waveform modeling, and a joint inversion of seismic velocities with transition-zone thickness, we constrain the fine-scale geometry and thermal structure of the gap. Sharp lateral boundaries are consistent with a mechanical opening within the stagnant slab, and gap temperatures are comparable to ambient upper-mantle values and >200 degrees C lower than plume-like temperatures. The planform of the gap aligns with the path of a migrating triple junction, suggesting formation through progressive slab tearing during plate-boundary reorganization. These observations demonstrate that a slab gap can persist without hot upwelling, consistent with the diffuse intraplate volcanism above the region.

키워드