Uranium-bearing quartz pebble conglomerates of the Mahagiri quartzite, Daitari –Tomka basin, Singhbhum craton, Eastern India : implications for provenance

The Precambrian Mahagiri Quartzite is exposed over an extensive area with radioactive Quartz Pebble Conglomerate (QPC) in chromiferous Sukinda valley of Odisha in Mahagiri hill of Daitari - Tomka Iron Ore Group basin around southern margin of Singhbhum Odisha Craton (SOC). The QPC lies unconformably above the Archaean granite greenstone terrain of SOC. Higher range of Chemical Index of Alteration (CIA) values of Mahagiri quartzite and conglomerate indicate their derivation from the highly weathered source. Major element data suggests that Mahagiri quartzite and conglomerate were deposited in a passive continental margin setting. The samples plot in Al₂O₃/TiO₂ vs SiO₂ variation diagram suggest a mixed felsic and mafic provenance, such as, Archaean Singhbhum granite greenstone terrain. The Archaean Singhbhum granite greenstone terrain comprises felsic components like evolved Singhbhum granite containing higher intrinsic uranium. The mafic components of Singhbhum greenstones, represented by basic, ultrabasic and various schists of Archaean Iron Ore Group, contain anomalous gold. Hence Mahagiri quartzite and conglomerate, derived from the favourable fertile Singhbhum granite greenstone provenance, as inferred by this study, provides a scope for exploration of palaeoplacer hosted U and gold in eastern India. (author)