Lithospheric-folding-based understanding on the origin of the back-arc basaltic magmatism beneath Jeju volcanic island

Compression near collisional plate boundaries causes lithospheric folding which results in the decrease of the pressure beneath the ridge of the fold while the pressure beneath the trough increases. The decompression beneath the lithosphere is likely to bring on basaltic magmatism along and below the ridge. We investigate the subsurface structure beneath Jeju (Cheju) volcanic island and its vicinity, and propose an alternative hypothesis that the basaltic magma beneath the island could be caused by (episodic) lithospheric folding. Unlike the prevailing hypothesis of the intraplate basaltic magmatism that requires extending lithosphere, our hypothesis can explain how the basaltic magma could be generated at the back‐arc regions without the extension. Key Points Lithospheric folding could cause the intra‐plate basaltic magmatism Gravity/magnetic field indicates large amount of hidden subsurface basaltic rock It is an alternative hypothesis for the origin of Jeju back‐arc volcanic island