Diverse crust-forming mechanisms on early Earth from the Hadean–Eoarchean (4.0–3.6 Ga) zircon record of the Tanzanian Craton

Integrated U-Pb geochronology, trace element, and Hf isotope geochemistry of detrital zircon from Eoarchean–Paleoarchean quartzites from the central Tanzanian Craton document derivation from Eoarchean and Hadean crust. Concordant U–Pb ages predominantly range from 3900 to 3600 Ma, with prominent age populations at 3900 Ma, 3770 Ma, and 3700 Ma; two samples also contain rare ca. 4050 Ma grains. Ti-in-zircon thermometry yields apparent crystallization temperatures between 580 °C and 840 °C (assuming SiO₂ and TiO₂ activities of unity), consistent with magmatic temperatures from the granitic water-saturated solidus up to temperatures experienced by intermediate-composition magmas. Trace element systematics (U-Yb-Y-Hf-Nb) show similarities to zircon from continental arc-ocean island settings but show some marked differences from other known similar age zircon localities (e.g., Jack Hills and Acasta Gneiss Complex). Zircon Hf isotopic compositions are dominated by chondritic sources over the ∼400 Myr span of magmatism sampled by the Tanzanian quartzites, contrasting with the more unradiogenic Hf signatures from other cratons of this age. A panoptic view of elemental and isotopic signatures recorded across different Hadean–Eoarchean zircon records provides support for diverse crust-forming processes on early Earth.