Evolution of the crustal magma plumbing system during the build-up to the 22-ka caldera-forming eruption of Santorini (Greece)

G.N. Fabbro (1) , Timothy H. Druitt (1) , Stéphane Scaillet (2)

1 LMV - Laboratoire Magmas et Volcans
2 ISTO - Institut des Sciences de la Terre d'Orléans - UMR7327

The formation of shallow, caldera-sized reservoirs of crystal-poor silicic magma requires the generation of large volumes of silicic melt, followed by the segregation of that melt and its accumulation in the upper crust. The 21.8 ± 0.4-ka Cape Riva eruption of Santorini discharged >10 km3 of crystal-poor dacitic magma, along with <0.004 km3 year-1. Rapid ascent and accumulation of the Cape Riva dacite may have been caused by an increased flux of mantle-derived basalt into the crust, explaining the occurrence of hybrid andesites (formed by the mixing of olivine basalt and dacite in approximately equal proportions) in the Cape Riva and late Therasia products. Pressurisation of the upper crustal plumbing system by sustained, high-flux injection of dacite and basalt may have triggered the transition from prolonged, largely effusive activity to explosive eruption and caldera collapse.

Keywords: Santorini; Magma reservoirs; Melt accumulation; Crystal residence timescales; Calderas

Domains: Volcanology; Global Changes

G.N. Fabbro, Timothy H. Druitt, Stéphane Scaillet. Evolution of the crustal magma plumbing system during the build-up to the 22-ka caldera-forming eruption of Santorini (Greece). Bulletin of Volcanology, 2013, 75, pp.1-22. ⟨10.1007/s00445-013-0767-5⟩. ⟨insu-00914757⟩