FLUID REGIME OF MANTLE PLUMES

Abstract

Available information on the geochemistry of volatile components in mantle-derived magmas suggests that the material of deep plumes is characterized by moderate contents of volatile components similar or even lower than the bulk silicate Earth abundances. There is no evidence for an additional input of volatile components, for instance, in the form of deep fluid flows from the Earth's core, i.e., there is no support for the "wet spot" concept. The appearance of magmas with high contents of volatile components at the base of magma-producing plume systems is explained by their extraction at low degrees of partial melting. Even if the presence of volatile components is taken into account, the estimated temperatures of plume material at the early stages of magma formation are much higher than the temperatures of the upper portion of the asthenosphere, which is consistent with the thermal nature of mantle plumes.