Mafic granulites from the North China craton can be divided into two textural types,
referred to as A- and B-types. A-type mafic granulites display garnet+quartz symplectic coronas, and
outcrop in the eastern and western zones of the craton, whereas B-type mafic granulites exhibit
orthopyroxene+plagioclase±clinopyroxene symplectites or coronas, and are mainly exposed in the
central zone of the craton. Most A-type mafic granulites preserve the prograde (M1), peak (M2) and
post-peak near-isobaric cooling (M3) assemblages, which are represented respectively by inclusions
of hornblende+plagioclase+quartz, a peak mineralogy of
orthopyroxene+clinopyroxene+plagioclase+quartz+garnet, and overprinted by garnet+quartz
symplectic coronas. These mineral assemblages and their P–T (pressure-temperature) estimates define anticlockwise P–T evolutionary paths.
The B-type mafic granulites preserve the peak (M1), post-peak near-isothermal decompression (M2)
and cooling (M3) assemblages, which are represented by the peak assemblage of
orthopyroxene+clinopyroxene+plagioclase+quartz+garnet±hornblende, post-peak
orthopyroxene+plagioclase±clinopyroxene symplectites or coronas, and later hornblende+plagioclase+magnetite symplectites,
respectively. These mineral assemblages and their P–T estimates define clockwise P–T paths.The anticlockwise P–T paths of the A-type mafic granulites in the eastern and western zones of the
North China craton are consistent with a model of underplating and intrusion of mantle-derived
magmas. In combination with lithological, structural and geochronological data, the eastern and western
zones of the North China craton are considered to represent two continental blocks that developed
through the interaction of mantle plumes with the lithosphere from the Palaeoarchaean to the
Neoarchaean era. The B-type mafic granulites and associated rocks in the central zone represent a
magmatic arc that was metamorphosed and deformed during amalgamation of the eastern and western
continental blocks in the late Palaeoproterozoic era. The mineral reaction relations and clockwise
P–T paths of the B-type mafic granulites from the central zone record the tectonothermal history of
the collision that resulted in the final assembly of the North China craton at c. 1800 Ma.
Measuring the ‘Great Unconformity’ on the North China Craton using new detrital zircon age data
