At sufficiently high temperatures, the rock may undergo partial melting to form magma, which may then become the source of an igneous rock.
(the rock; may undergo; partial melting to form magma,; T:At sufficiently high temperatures) (magma; may become; the source of an igneous rock; T:then)
the rock magma
may undergo may become
partial melting to form magma, T:At sufficiently high temperatures
the source of an igneous rock T:then