Characterisation and U–Pb–Hf isotope record of the 3.55 Ga felsic crust from the Bundelkhand Craton, northern India

• First record of the 3.55 Ga felsic crust from northern India.
• Trondhjemite gneiss similar to typical Archaean low-HREE TTG.
• Trondhjemite formed by reworking of Eoarchaean mafic crust.
• Bundelkhand and Bastar Cratons in India preserve ∼3.58–3.55 Ga felsic crust.

To date, ca. 3.3 Ga tonalite-trondhjemite-granodiorite (TTG) gneisses from the Aravalli and Bundelkhand Cratons are the oldest rocks in northern India. However, the results of our combined U–Pb and Lu–Hf isotope study on zircon grains from a trondhjemite gneiss of the Bundelkhand Craton provide evidence for the formation of even older felsic crust of 3.55 Ga age in this part of India. The petrological and geochemical data reveal that the trondhjemite gneiss from the Bundelkhand Craton is characterised by a highly fractionated REE pattern [(La/Yb)N = 34.4] with low HREE contents, and positive Eu (Eu/Eu* = 1.52) and Sr anomalies. These features are consistent with melt extraction from a garnet-bearing and plagioclase-free source. Slightly subchondritic Hf compositions (ɛHf3.55Ga of −0.8 ± 0.3) and Hf model ages between 3.80 Ga and 3.95 Ga additionally indicate that the trondhjemite was formed by reworking of Eoarchaean mafic crust. This interpretation is in good agreement with age-Hf isotope data obtained from zircon grains worldwide. Furthermore, our new results indicate that the Bundelkhand and Bastar Cratons experienced an important granitoid emplacement event at 3.58–3.55 Ga.

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