A catalytic delamination-driven model for coupled genesis of Archaean crust and sub-continental lithospheric mantle

Episodic crustal growth in the southern segment of the Trans-North China Orogen across the Archean-Proterozoic boundary

“…TTGs might represent partial melts of hydrous mafic rocks at pressures high enough to stabilize garnet ± amphibole, thus producing tonalitic melts with a characteristic signature of high La/Yb and Sr/Y ratios (e.g., Drummond and Defant, 1990;Smithies, 2000;Martin et al, 2005;Condie, 2005). Subducting ocean crust under eclogite facies conditions Martin, 1999;Martin et al, 2005), thickened lower crust (Smithies, 2000;Condie, 2005) or delaminated lower crust (Zegers and van Keken, 2001;Bédard, 2006) would be the potential source for TTGs. Partial melts of the subducting ocean crust and delaminated lower crust would interact with peridotitic mantle during ascent, resulting in high MgO, Cr and Ni contents (e.g., Rapp et al, 1999;Smithies, 2000;Martin et al, 2005;Wang et al, 2006), which would be one of the principal characteristics distinguishing them from partial melts of thickened lower crust.…”

Neoarchean Mantle-derived Magmatism within the Repulse Bay Block, Melville Peninsula, Nunavut: Implications for Archean Crustal Extraction and Cratonization

“…The retention of ~2% rutile in a mafic source can also generate these anomalies (Bédard 2006;Bédard et al 2013). This 'arc-like' geochemical signature is also typical in Archean TTG and sanukitoid lithologies worldwide (e.g.…”

“…moderate to high pressure TTGs, sanukitoid intrusions, high-K granite) were formed (Laurent et al 2014). Alternative mechanisms for the formation of Archean lithologies do exist but remain untested (see Bédard 2006). Conversely, many investigations lend support to the probability of Archean (especially in the Neoarchean) subduction.…”

Neoarchean siliceous high-Mg basalt (SHMB) from the Taishan granite–greenstone terrane, Eastern North China Craton: Petrogenesis and tectonic implications

“…This mechanism is also feasible to explain their prevalence in the Archean of mantle wedge-derived high-Mg andesite, sanukitiods, boininites, Nb-enriched basalts, and adakites with higher Mg numbers than TTGs. However, although other models can also explain the production of TTGs in certain circumstances (e.g., Abbott, 1996;Hollings et al, 1999;Smithies, 2000;Smithies et al, 2003;Bédard, 2006), subduction-accretion might have played a more important role in the growth of continental crust in the Archean that is commonly recognized.…”