Granite system isotopic composition

Inert tracer movement. Consider the case of the movement of C through the pore space of a quartzite, pelite, or granitic rock, all of which do not contain any carbon (e.g. no calcite, scapolite or graphite). In this case, there will be no exchange of carbon isotopes between the mineral phases and the fluid. Hence the time derivative of the system composition reduces to that of the fluid phase, since the solid does not change its isotopic composition ... 

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