Rb–Sr ages of early Archaean supracrustal rocks and Amîtsoq gneisses at Isua

Intermediate P/T-type regional metamorphism of the Isua Supracrustal Belt, southern west Greenland: The oldest Pacific-type orogenic belt?

“…2a), is one of the oldest greenstone belts on Earth (Moorbath et al, 1977;Moorbath et al, 1973;Nutman et al, 1997;Nutman et al, 1996). Despite severe deformation, metasomatism, and metamorphism, the ISB preserves original structures such as pillows, hyaloclastite, and sheet flow in lavas and graded sedimentary layering in some places (Appel et al, 1998a;Appel et al, 1998b;Komiya et al, 1999).…”

Metamorphic fluid flow in the northeastern part of the 3.8–3.7Ga Isua Greenstone Belt (SW Greenland): A re-evalution of fluid inclusion evidence for early Archean seafloor-hydrothermal systems

“…Protoliths of the IGB include basaltic and high Mg-basaltic pillow lava and pillow lava breccia, cherts, banded-iron formation (BIF), ultramafic rocks, and minor sedimentary strata, such as conglomerates and garnet-mica-schists (Myers, 2002). The rocks are mostly strongly deformed and have been metamorphosed up to amphibolite facies, but despite this they have been reliably dated between 3.7 and 3.8 Ga (Moorbath et al, 1973(Moorbath et al, , 1977Nutman et al, 1996Nutman et al, , 2002. Several episodes of metasomatism affected the supracrustal rocks, some of which could have been related to seafloorhydrothermal events (Appel et al, 2001), others to metamorphic/magmatic fluid flow contemporaneous with tonalite emplacement (e.g.…”

Early Precambrian Earth history: plate and plume tectonics and extraterrestrial controls

“…The suite is thrust over the Amitsoq TTG gneiss dome (Fig. 6a), a part of the Itsaq gneiss complex (together with the Amalia complex and the Ameralik dikes) with isotope ages from 3850 to 3570 Ma (Moorbath et al, 1977;Nutman et al, 1996), and 3872-3847 Ma U-Pb zircon ages for the Amitsoq garnet-biotite gneiss (Rosing et al, 1996). The compositions of picrites and pillow basalts in the Isua Group, as well as most of related pillow lavas and gabbro, correspond to MORB, both in REE and multielement spectra (Polat et al, 2008).…”