Mesoarchean partial melting of mafic crust and tonalite production during high-T--low-P stagnant tectonism, Akia Terrane, West Greenland

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Different geodynamic models exist for the growth and differentiation of Archean continental crust, ranging from horizontal tectonics with subduction zones to vertical tectonics with foundering of greenstone sequences. U–Pb zircon geochronology, field relationships, and pressure–temperature constraints from granulite-facies metabasite of the Akia Terrane of the North Atlantic Craton in West Greenland show that this terrane grew through two major magmatic growth episodes: an earlier one at c. 3.2 Ga, and a later one at c. 3.05–2.97 Ga. Phase equilibrium modelling for assemblages related to the latter indicates temperatures of >800 °C at <0.9 3.0 a absence akia and apparent as at by c. consistent crust. current deformation ductile element exposure ga generated geothermal gneiss. gpa, gradient granulite-facies high implies in indicated leucosome level melting metabasite metamorphism modelling nebulitic, occurred of partial pervasive pressures pyroxene-bearing suggests terrane that the thin tonalite trace undeformed was with>0.8 GPa in the stability field of garnet. U–Pb zircon geochronology and existing Hf isotope data are also consistent with a model involving protracted Mesoarchean magmatic growth with limited mantle addition during a prolonged period of high temperatures in a relatively stagnant tectonic regime prior to Neoarchean compressional tectonism in the Akia Terrane.
TidsskriftPrecambrian Research
StatusUdgivet - 2020

ID: 234898896