Stepwise magma migration and accumulation processes and their effect on extracted melt chemistry

Abstract

Numerical and analogue models suggest that melt production, its segregation from the solid matrix and subsequent transport and accumulation are highly dynamic and stepwise processes exhibiting scale invariant patterns in both time and length scales, which is characteristic of self-organized critical systems. This phenomenon is also observed in migmatites at several localities, where the leucosome thickness statistics obey power laws. Stepwise melt transport and deformation-enhanced melt mobility affect melt production dynamics by determining the distribution of extracted melt batch sizes and residence times of melt pockets within the host rock, which in turn would influence the geochemistry of extracted melts. We introduce a numerical approach, which enables qualitative and quantitative assessment of the effects of stress-induced melt migration and accumulation on the chemistry of partial melts. The model suggests that apart from different sources and melting percentages, deformation can be an important factor in producing geochemical variations within and between intrusive/extrusive complexes.

Keywords

• analogue modelling
• melt segregation
• migmatites
• fractals
• self-organized criticality
• melt chemistry