Magma residence time beneath the Piton de la Fournaise Volcano, Reunion Island, from U-series disequilibria

At the time of eruption, (210Pb/226Ra)0 in both oceanites and basalts from the Enclos and rift-zones spans a narrow range with a mean value of 0.68, with the exception of the 1945 basalt which has an unusually low ratio of 0.20. The value of 0.68 can be explained by Rn degassing from the shallow magma chamber on a timescale comparable to that deduced from the evolution of (226Ra/230Th)0 in the 1960-1998 period.