Dynamic Model of the Infiltration Metasomatic Zonation

A new dynamic model of infiltration metasomatic zonation is discussed. The model describes the formation and evolution of metasomatic zoning patterns in terms of travelling fronts and waves. Travelling fronts cause the formation of well known vectoral zonation. All replacement reactions in this zonation are localized immediately around fronts (zone boundaries), and inside individual zones the chemical equilibrium is attained. Such a condition corresponds to the “local equilibrium model” and no regular oscillations occur. Travelling waves can stimulate stable spatial chemical oscillations and appearance of the dissipative structure in the solution flow, if redox reactions such as Fe2+ ↔ Fe3++ e– in solution occur. Corresponding to the evolution of the dissipative structure, the rhythmical banding in the metasomatic rocks is formed. Thus the proposed model describes the single approach as vectoral as periodic (rhythmically banded) zoning patterns.