There have been many different ages found for ophiolite. We have researched these ages through fieldwork and microscopy to identify three types of dunite. These are useful ways to research the origin of ophiolitic magma. The Purang ophiolite, which crops out over an area of about 650 km² in the western Yarlung–Zangbo suture zone, chiefly consists of mantle peridotite, pyroxenite and gabbro. It is a useful ultra-massif for showing the multistage nature of ophiolite.