Andrea Piccolo, Richard W. White, Boris J.P. Kaus , Richard M. Palin , Georg S Reuber

Many Archean terranes are interpreted to have a tectonic and metamorphic evolution that indicates
intra-crustal reorganization driven by lithospheric-scale gravitational instabilities. These processes
are associated with the production of a significant amount of felsic and mafic crust, and are widely
regarded to be a consequence of plume-lithosphere interactions. The juvenile Archean felsic crust
is made predominantly of rocks of the tonalite–trondhjemite–granodiorite (TTG) suite, which are
the result of partial melting of hydrous metabasalts. The geodynamic processes that have assisted
the production of juvenile felsic crust, are still not well understood. Here, we perform 2D and 3D
numerical simulations coupled with the state-of-the-art of petrological thermodynamical modelling
to study the tectonic evolution of a primitive Archean oceanic plateau with particular regard on the
condition of extraction of felsic melts. In our numerical simulations, the continuous emplacement
of new, dry mafic intrusions and the extraction of the felsic melts, generate an unstable lower
crust which drips into the mantle soon after the plume arrival. The subsequent tectonic evolution
depends on the asthenosphere T P . If the T P is high enough (≥ 1500 ◦ C) the entire oceanic crust is
recycled within 2 Myrs. By contrast at low T P , the thin oceanic plateau slowly propagates generating
plate-boundary like features.