Detrital zircon ages from Archaean conglomerates in the Singhbhum Craton, eastern India: implications on economic Au-U potential

Abstract New U–Pb age and Hf isotope data obtained on detrital zircon grains from Au- U-bearing Archaean quartz-pebble conglomerates in the Singhbhum Craton, eastern India, specifically Upper Iron Ore Group Badampahar Greenstone Belt Phuljhari Formation below Dhanjori provide insights into provenance maximum of sediment deposition. The most concordant, least disturbed 207 Pb/ 206 Pb ages cover entire range known magmatic higher grade metamorphic events craton 3.48 to 3.06 Ga show a broad between 3.38 3.18 Ga. This overlap is also mimicked by Lu–Hf analyses, which returned wide ? (t) values + 6 ? 5, agreement with igneous rocks Craton. A smaller but distinct peak centred at corresponds last major intrusive event, emplacement Mayurbhanj Granite associated gabbro, picrite anorthosite. Thus, these must form basement rather than being studied as previously interpreted. corresponding all have subchondritic isotopic composition. youngest reliable 3.03 case basal east 3.00 for set an upper limit conglomerate sedimentation. Previously published similarly Au-bearing Mahagiri Quartzite south gave somewhat younger sedimentation 2.91 There, lower given relationship c. 2.8 granite. time window thus defined deposition Craton almost identical span established the, places, U-rich Kaapvaal South Africa: 2.98–2.78 Dominion Witwatersrand Supergroup Africa. Since recognition first concentration gold Earth’s surface microbial activity having taken place around 2.9 Ga, independent nature hinterland, above similarity substantially increases potential discovering Witwatersrand-type and/or uranium deposits Further constraints are needed there, however, distinguish supposedly less fertile (with respect Au) > more < successions.