Partitioning of transition metal ions during metamorphic processes

8 Partitioning of transition metal ions during metamorphic processes 

Metamorphic processes involve the recrystallization of minerals under various degrees of isochemical conditions. The reaction 

At the onset of diagenesis of wet sediments and metamorphism of lithified rocks there are substantial amounts of intergranular aqueous and saline solutions. As the grade of metamorphism increases, the porosity and permeability of a rock decrease and intergranular fluids become less continuous and more localized. As a result, the availability of ions for metamorphic reactions becomes increasingly dependent on the composition of the rock in situ. 

The mechanism of a metamorphic reaction might be visualized as follows 

existing minerals partially dissolve in the intergranular fluid with precipitation and growth of the new mineral taking place at the expense, both compositionally and spatially, of the existing minerals. 

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