How Small-volume Basaltic Magmatic Systems Develop: a Case Study from the Jeju Island Volcanic Field, Korea

Research on Jeju Volcanic Island reveals that small-volume basaltic magmatic systems develop through distinct stages of mantle melting and fractionation, influenced by subduction processes. The study found that while older monogenetic centers (4.07 Ma) show significant olivine fractionation, younger ones (5.02 Ma) exhibit deeper clinopyroxene and olivine fractionation. Isotopic data indicate two contrasting sources: a shallower one for high-Al alkali and subalkali lavas, and a deeper one for low-Al alkali magmas. The authors propose that mantle melting began under partially hydrous conditions at ~2.5 GPa, transitioning to drier conditions and extending to 3-3.5 GPa, increasing melt volume from shallower zones. This process may have been triggered by accelerated heat transfer or increased mantle upwelling, potentially linked to tectonic events such as the opening of the Sea of Japan (~15 Myr ago) and Philippine Sea plate rotation (~2 Ma).

Brenna, M., Cronin, S. J., Smith, I. E. M., Maas, R., & Sohn, Y. K. (2012). How Small-volume Basaltic Magmatic Systems Develop: a Case Study from the Jeju Island Volcanic Field, Korea. Journal of Petrology, 53(5), 985–1018. https://doi.org/10.1093/petrology/egs007