What geological process change sediment into shale shale into slate and slate into magma?

Sediment is transformed into shale through lithification, a process involving compaction and cementation under pressure. Shale can then metamorphose into slate through regional metamorphism, where heat and pressure alter its mineral structure. If slate is subjected to even higher temperatures and pressures, it can further metamorphose into schist or gneiss. Ultimately, intense heat can melt these metamorphic rocks into magma through partial melting.