Petrogenesis of metavolcanics and detrital zircon geochronology of the Mesoarchean western Iron Ore Group supracrustals, Singhbhum Craton (India): Evidence for an intracontinental extension setting

Vestiges of Earth’s earliest depleted mantle reservoir

“…It has been problematic to compare the depleted ɛ 143 Nd signature reported from the Singhbhum craton by other studies to that recorded by the western Iron Ore Group Lower Lava in the current study. This is because these previously reported ages and initial ε Nd values were either not derived from an isochron (e.g., Chaudhuri et al, 2017;Pandey et al, 2019;Asokan et al, 2023), derived from an errorchron (e.g., Pandey et al, 2019;Maltese et al, 2022), from samples significantly affected by crustal contamination (e.g., Adhikari 2021a, 2021b; Chaudhuri et al, 2017), or associated with an isochron-derived age that does not agree with other independent stratigraphic chronometers (e.g., Basu et al, 1981;Adhikari et al, 2021b;Adhikari and Vadlamani, 2022). It is important to specify that the assumed initial ɛ Nd value of +5.2 for a single Singhbhum granitic sample accepted by Pandey et al (2019) and reused by Maltese et al (2022) was calculated not from a reliable isochron but from using a single U-Pb zircon age whose 147 Sm-143 Nd data also formed an errorchron (very high MSWD) according to Pandey et al (2019).…”