ABSTRACT
In general, the C of metamorphic rocks can have diverse sources. C can be derived from the mantle or lower levels of the Earth's crust with metamorphic fluid during the process of metamorphism. Alternatively, C may be inherited from the protoliths before their metamorphism. We can suggest that in cases where there is a sufficiently large resource of external C-bearing fluid, or if there is a high fluid/ rock ratio during metamorphism, the C isotopic composition of various rocks will be similar, on the average, regardless of the origin of the rock. However, in the case of metamorphic rocks with distinctly different C isotopic compositions, which can be certainly related to their lithologic composition, where there are limited external C-bearing fluids or the fluid/rock ratio was small, then the primary heterogeneity of the C isotopic composition of the protoliths would be little changed. We have examined the question of C sources and amounts of C-bearing fluid associated with metamorphism using of two metamorphic complexes in the eastern Siberia.
