Paleo-Viscometry of Magma Bodies

Viscosity and water content are among the most important characteristics of magma bodies. However, once magma has erupted or solidified, such properties of the original magma are difficult to constrain directly. For an ensemble of rhythmically layered magmatic sills and dikes we present a simple model of crystallization and crystal settling that allows one to obtain a melt viscosity estimate when combined with field observations. If the composition of the parental magma is roughly known and an estimate of its liquidus temperature is known, the viscosity can be used to infer water content.