Protolith
From Wikipedia, the free encyclopedia
Protolith refers to the precursor rock of a given lithology.
Granitoids can for instance be derived through melting of a sedimentary rock, and thus have a sedimentary protolith, or be derived from a magmatic precursor, and thus have a magmatic protolith.
Metamorphic rocks can be derived from any other rock and thus have a wide variety of protoliths.
Identifying a protolith is a prime aim of metamorphic geology and igneous geology.