Hadean greenstones from the Nuvvuagittuq fold belt and the origin of the Earth's early continental crust

Protocrustal evolution of the Nuvvuagittuq Supracrustal Belt as determined by high precision zircon Lu–Hf and U–Pb isotope data

“…mafic or tonalitic crust). To be sure to include the possible range of model ages for the NSB zircons analysed here, we have calculated model ages using a maximum 176 Lu/ 177 Hf of 0.026, corresponding to the average of the enriched low-Ti metamafic rocks of the NSB (Adam et al, 2012;O'Neil et al, 2013;Section 4.3.2), and a minimum equal to that of the lowest recorded 176 Lu/ 177 Hf for a low-Ti enriched metamafic rock from the NSB of 0.007 ( Fig. 3; Guitreau et al, 2013).…”

Early life on land and the first terrestrial ecosystems

“…Regardless, it is assumed that the Moon was already formed before 4,400 Ma (Canup and Righter 2000;Yu and Jacobsen 2011) and that the Earth's nucleus, mantle, and lithosphere were already differentiated (Nelson 2004;Boyet and Carlson 2005). At least by~4,200 Ma, but perhaps 200 Ma earlier, large water bodies were in place (Mojzsis et al 2001;Nutman 2006;Cavosie et al 2007, but see alternative views by Deming 2002), while granitic (continental) and basaltic (oceanic) crusts were constantly growing, resurfacing, and remelting, interacting with water in non-uniform regimes that evolved drastically from the Hadean to the Neoarchean (Komiya et al 1999;Nutman et al 2002;Myers 2004;Rino et al 2004;Van Kranendonk 2004 and references therein;Furnes et al 2007a;Adam et al 2012), changing from plume-dominated to platedominated tectonics toward the late Paleoarchean . It is plausible then, that by the end of the heavy bombardment (Gomes et al 2005;Hartmann et al 2000) some~3,800 Ma ago, the primitive lands and oceans were open niches ready for the pioneering and rapidly evolving microscopic life forms, for which occasional "sterilizing" perturbations may be irrelevant given the resilience and time scales at which biology operates compared to geology.…”

“…The earliest remnants of continental crust may derive from ≥3,500 Ma-old submillimeter zircons (Nutman 2006) and regional rock outcrops (Buick et al 1995;Iizuka et al 2006;Stern and Scholl 2010;Adam et al 2012). Supplementary evidence for exposed lands may consist of thick soils developed on these ancient surfaces (Buick et al 1995;Hoffman 1995;Ohmoto et al 2007;Johnson et al 2009Johnson et al , 2010.…”

Evolution of the Earth: Plate Tectonics Through Time

“…Tessalina et al (2010) reported 142 Nd/ 144 Nd variations in Archean cherts and lavas that were likely derived at the expense of Hadean rocks that persisted at that time. Greenstones within the Nuvvuagittuq region of Québec have 142 Nd/ 144 Nd variations (Adam et al, 2012;O'Neil et al, 2008O'Neil et al, , 2011O'Neil et al, , 2012. O'Neil et al (2012) proposed that these mafic rocks erupted at $4.4 Ga and then were intruded by gabbros at $4.2 Ga, using the revised half-life of 146 Sm (Kinoshita et al, 2012).…”

“…In particular, the causes of onesided subduction are better understood (Crameri et al, 2012), allowing global geochemical history models to presume its existence. O'Neil et al (2008O'Neil et al ( , 2011O'Neil et al ( , 2012 and Adam et al (2012) studied Hadean greenstone and intrusive gabbro in the Nuvvuagittuq region of Quebec. Detection of antineutrinos from radioactive decay of Th and U has the potential to constrain heat production in the Earth's interior (Dye, 2012;Mareschal et al, 2012;Šrámek et al, 2012).…”