Abstract
Felsic continental crust is unique to the Earth in the solar system, but
it still remains controversial regarding its formation, accretion and
reworking. The plate tectonics theory has been significantly challenged
in explaining the origin of continents as Archean continents rarely
preserve hallmarks of plate tectonics. In contrast, growing evidence
emerges to support mantle plume-derived oceanic plateau models as the
models can reasonably explain the origin of bimodal volcanic assemblages
and nearly coeval emplacement of tonalite-trondjhemite-granodiorite
(TTG) rocks, presence of ~1600ºC komatiites and dominant
dome structures, and lack of ultra-high-pressure rocks, paired
metamorphic belts and ophiolites in Archean continents. Although plate
tectonics seems to fail in explaining the origin of continents, it has
been successfully applied to interpret the accretion or outgrowth of
continents along subduction zones where new mafic crust is generated at
the base of continental crust through partial melting of the mantle
wedge with addition of H2O-dominant fluids from the subducted oceanic
slabs, and partial melting of the juvenile mafic crust results in the
formation of new felsic continental crust, leading to the outside
accretion of continents. Subduction processes also cause the softening,
thinning and recycling of continental lithosphere due to the vigorous
infiltration of volatile-rich fluids and melts especially along weak
layers or weak belts, leading to the widespread reworking and even
destruction of continental lithosphere. Reworking of continents also
occurs in continental interiors due to plume-lithosphere interactions,
which, however, leads to much less degrees of lithospheric modification
than subduction-induced craton destruction.