[3] Due to its age and low metamorphic grade [4] relative to many Eoarchaean rocks, the Isua Greenstone Belt has become a focus for investigations on the emergence of life[5][6] and the style of tectonics that operated on the early Earth.

[10] The greenstone belt comprises two major sequences of metamorphosed mafic volcanic and sedimentary rocks, which were divided on the basis of zircon uranium-lead dating.

[3] The Isua Greenstone Belt is bounded to the West by the Ivinnguit Fault, which divides the Eoarachaean Itsaq Gneiss Complex from younger (Mesoarchaean) rocks of the Akia Terrane.

These include subdivision of the various lithologies and units within the belt using a combination of geological mapping and U-Pb zircon dating, typically using sensitive high-resolution ion microprobe (SHRIMP), analyses;[3] major and trace element chemistry;[11][12] structural analyses;[6][7][13] geothermobarometry and metamorphic modelling using phase diagrams to determine metamorphic conditions;[4][14] and a wide range of stable,[15][16] radiogenic,[17] and short-lived isotope systems.

[22] Some peridotite lenses have been interpreted as obducted mantle fragments,[23] and used as evidence to support the operation of plate tectonics during the formation of the Isua Greenstone Belt.

Furnes et al. (2007) suggested that the presence of pillow lavas and closely spaced parallel dykes indicated that the Isua Greenstone Belt represented an ophiolite.

[20][26][31] However, subsequent studies have pointed out that the boninite-like amphibolites are in fact low-titanium basalts, with too little silica to classify as boninites,[12] and recent geochemical modelling suggests that the entire volcanic compositional range at Isua can be explained without requiring a plate tectonic setting.

[24] If this is the case, then no thrusting is required to bring them into contact with the supracrustal rocks, and the dunite lenses do not provide evidence that the Isua Greenstone Belt is an ophiolite.

[7] This model can account for the mafic composition of pelitic sediments at Isua, suggesting there was little felsic crust present during its formation,[11] and the relatively simple deformation and uniform metamorphic grade observed across the belt.

[4][14][35][37] The effect of these two metamorphic and deformational events adds significant complexity to interpreting the primary geochemical compositions and geological structures present in the belt (e.g., see below).

"Unless some unknown abiotic process exists which is able both to create such isotopically light carbon and then selectively incorporate it into apatite grains, our results provide evidence for the emergence of life on Earth by at least 3,800 Myr before present.

"[15] In August 2016, an Australia-based research team presented evidence that the Isua Greenstone Belt contains the remains of stromatolite microbial colonies that formed approximately 3.7 billion years ago.

[42] The stromatolite fossils appear wavy and dome-shaped, are typically 1–4 cm (0.4–1.6 in) high, and were found in iron- and magnesium-rich dolomites that had recently been exposed by melting snow.

[42][40] Some geologists interpret the textures above the putative stromatolites as sand accumulation against their sides during their formation, suggesting that the features arose during the sedimentary process, and not through later, metamorphic deformation.

[40] In 2016, geologist and areologist Abigail Allwood stated that the discovery of Isua stromatolites makes the emergence of life on other planets, including Mars early after its formation, more probable.