Partial melting of ultrahigh-pressure metamorphic rocks during continental collision: Evidence, time, mechanism, and effect

•Petrological evidence for partial melting of UHP metamorphic rocks during continental collision is summarized.•The P-T conditions and timing for the anatexis of UHP rocks are reviewed.•The dehydration reaction of hydrous minerals serves as the major mechanism for the anatexis during exhumation.•Geochemical differentiation is significant during the low-degree partial melting of crustal rocks.