The influence of magma plumbing complexity on monogenetic eruptions, Jeju Island, Korea

Abstract

Continuous pyroclastic successions from monogenetic volcanoes in the Jeju Island Volcanic Field (Korea) were targeted for detailed geochemical investigations of juvenile ejecta to show that multiple distinct magma pulses may be erupted during a single monogenetic eruption. Deeply derived, and possibly multiply sourced, evolving magma pulses may erupt sequentially from the same vent and form generally uninterrupted depositional sequences with continuous chemical trends. Alternatively, pulses can rise independently, resulting in breccia horizons and truncation surfaces in depositional sequences and in stepped and mixed chemical trends. We infer that uninterrupted eruptions result from clear plumbing systems in which a single large dyke system feeds an eruption and where differently sourced magmas are erupted independently. Congested plumbing systems consisting of dyke complexes give rise to vent shifts, asymmetrical eruptive centres and composite depositional sequences. Integration of chemical variation and eruptive dynamics provides a powerful means of understanding monogenetic volcanoes.