Igneous experiments on melts and crystals

Abstract

The first igneous experiments were done just to prove that lavas were once molten (this obviously would not have been necessary if the experimenter had lived on Hawaii or Iceland). Tuttle & Bowen (1958) had the same objective when they proved that granites could form from magmas containing significant amounts of H₂O. The objectives of modern experimental igneous petrologists include the following:

• (a) To determine the processes occurring during magma evolution such as crystal fractionation, magma mixing, etc. This includes determining the P, T, and intensive variable conditions under which the processes occur, and the relationships of the processes to tectonic models.

• (b) To use magmas as windows to their source regions at depth. If one can “see through” the evolutionary events in the history of magmas, they can be used to estimate the P and T of their sources in the lower crust or upper mantle. Knowing the P–T conditions at the source constrains its thermal history.

• (c) To use magma composition to constrain the chemical make-up of the source regions.