Surface subsidence caused by mantle plumes and volcanic loading in large igneous provinces

Large igneous provinces form with massive flood basalts being erupted over a large region within a few million years. A prevailing model for their formation is a mantle plume model in which a plume head originates from the core–mantle boundary, ascends through the mantle, and produces topographic uplift and eventually massive melting at the surface. However, many geological observations indicate surface subsidence in the central region before or during flood basalt eruptions. In this study, we demonstrate that a plume head temporarily ponding below the 660-km phase change boundary causes significant subsidence at the Earth's surface over an extended period before the eruption, and that the loading from erupted basalts causes surface subsidence at the periphery of the eruption area that affects the environment for subsequent episodes of basalt eruptions. Our studies therefore demonstrate that the observed subsidence history in many flood basalt provinces is characteristic of the dynamics of mantle plumes and may be used as diagnostics for identifying plume-induced flood basalt events.