The reworked crust can be attributed to the burial, most likely through subduction, of hydrated materials, such as basalt, that were formed in the Hadean. Additionally, the source for tested rock samples came from a mantle depleted in titanium and niobium and enriched in lead, strontium, barium, rubidium, and light rare-earth elements, which, taken together, are indicative of arc-related basalts. The diorites found in the area are high in magnesium and REE (rare-earth elements), which suggest further that the rocks were formed from a mixture of the mantle and remelted basaltic crust. Overall, the presence of tonalite-trondhjemite-granodiorites, as well as the iron present for the banded iron formations (BIFs), are determined to have been caused by hydrothermal alteration at high temperatures. BIFs are typically found in intra-oceanic, arc or forearc settings, which are associated with convergent boundaries. The intrusions were formed when upwelling asthenosphere partially melted thick overlying oceanic crust. It is thought that the melting and reworking of oceanic crust formed the early Archean continental crust. In addition, the eclogite residues, formed by the partial melting of the oceanic crust, subsequently became a part of the sub-continental lithospheric mantle. By using uranium-lead dating on zircons, scientists were able to determine that the process of creating the Isua Greenstone Belt took approximately 300 million years.