Plume and arc magmatism in the Abitibi subprovince: Implications for the origin of Archean continental lithospheric mantle

摘要: Abstract Based on eclogitic mantle xenoliths that appear to be the residue of slab melts, it is commonly argued formation distinctive lithospheric keels beneath Archean cratons occurred by tectonic accretion oceanic crust. These models are complicated evident buoyancy keels, varied compositions xenolith suite as a whole, and compositional constraint large portion originated in plume melting events. Resolution these issues long development history most (100’s m.y.) multiple cycles magmatism they represent. In contrast, single 50 m.y. period arc volcanism Abitibi subprovince, immediate onset orogeny craton stabilisation, avoids many uncertainties. Chemical isotopic data demonstrate syn-volcanic syn-tectonic adakitic granitoids were derived via melting. Deep seismic reflection profiles image singular slab-like features along Moho. interpreted remnants slabs emplaced torn during orogeny. Nonetheless, their presence directly contradicts subcretion keel because occupy regions should correspond top an earlier-formed subcreted keel. Post-adakite shoshonitic lamprophyres also attest metasomatised wedge throughout entire magmatism. Diamond-bearing adjacent Wawa subprovince compositionally equivalent Paleoproterozoic diamondiferous rocks characteristic adakite-generating shallow subduction rather than evidence pre-existing sub-cratonic keels. plume- subduction-related demonstrates continuous asthenospheric belt over period. Komatiites then boninites erupted central part belt, halfway through its evolution, rifted arc-style dominated within few m.y. None events consistent with progressively thickened continental The geodynamic evolution fact recognised some studies: association deep was not developed gradually greenstone volcanism. Rather, initiated coupling imbricated arc-related crust buoyant rose from depths 80 km >400 km. Subduction active southern eastern margin Superior Province before after ascent plume. Renewal Abitibi, marked occurrence ∼2716 Ma boninitic volcanic suite, delayed composite Final following loss may have included entrainment fragmented into rising diapir. soon keel’s Phanerozoic diamond deposits, chemistry geophysical data.