Evidence of Enriched, Hadean Mantle Reservoir from 4.2-4.0 Ga zircon xenocrysts from Paleoarchean TTGs of the Singhbhum Craton, Eastern India

Trisrota Chaudhuri; Yusheng Wan; Rajat Mazumder; Mingzhu Ma; Dunyi Liu

doi:10.1038/s41598-018-25494-6

Evidence of Enriched, Hadean Mantle Reservoir from 4.2-4.0 Ga zircon xenocrysts from Paleoarchean TTGs of the Singhbhum Craton, Eastern India

Sci Rep. 2018 May 4;8(1):7069. doi: 10.1038/s41598-018-25494-6.

Authors

Trisrota Chaudhuri¹, Yusheng Wan², Rajat Mazumder³, Mingzhu Ma², Dunyi Liu²

Affiliations

¹ Department of Geology, University of Calcutta, 35, Ballygunge Circular Road, Kolkata, 700019, India.
² Beijing SHRIMP Center, Institute of Geology, Chinese Academy of Geological Sciences, Beijing, 100037, China.
³ Department of Applied Geology, Faculty of Engineering and Science, Curtin University Malaysia, CDT 250, Miri, 98009, Sarawak, Malaysia. rajat.m@curtin.edu.my.

Abstract

Sensitive High-Resolution Ion Microprobe (SHRIMP) U-Pb analyses of zircons from Paleoarchean (~3.4 Ga) tonalite-gneiss called the Older Metamorphic Tonalitic Gneiss (OMTG) from the Champua area of the Singhbhum Craton, India, reveal 4.24-4.03 Ga xenocrystic zircons, suggesting that the OMTG records the hitherto unknown oldest precursor of Hadean age reported in India. Hf isotopic analyses of the Hadean xenocrysts yield unradiogenic ¹⁷⁶Hf/¹⁷⁷Hf^initial compositions (0.27995 ± 0.0009 to 0.28001 ± 0.0007; ɛHf[t] = -2.5 to -5.2) indicating that an enriched reservoir existed during Hadean eon in the Singhbhum cratonic mantle. Time integrated ɛHf[t] compositional array of the Hadean xenocrysts indicates a mafic protolith with ¹⁷⁶Lu/¹⁷⁷Hf ratio of ∼0.019 that was reworked during ∼4.2-4.0 Ga. This also suggests that separation of such an enriched reservoir from chondritic mantle took place at 4.5 ± 0.19 Ga. However, more radiogenic yet subchondritic compositions of ∼3.67 Ga (average ¹⁷⁶Hf/¹⁷⁷Hf^initial 0.28024 ± 0.00007) and ~3.4 Ga zircons (average ¹⁷⁶Hf/¹⁷⁷Hf^initial = 0.28053 ± 0.00003) from the same OMTG samples and two other Paleoarchean TTGs dated at ~3.4 Ga and ~3.3 Ga (average ¹⁷⁶Hf/¹⁷⁷Hf^initial is 0.28057 ± 0.00008 and 0.28060 ± 0.00003), respectively, corroborate that the enriched Hadean reservoir subsequently underwent mixing with mantle-derived juvenile magma during the Eo-Paleoarchean.