Mesoarchaean mafic–ultramafic Ikauna layered intrusion, Bundelkhand craton, India: geology, U–Th–Pb age (SHRIMP) and correlation

ABSTRACT

Mafic–ultramafic rocks, occurring as intrusions in the Ikauna area, are a well-differentiated complex comprising dunite (serpentinite), pyroxenite, gabbro, and gabbro-pegmatite in the southern Bundelkhand craton. This complex intruded into Palaeo-Mesoarchaean TTG and was cut by Neoarchaean granites. The age of a late stage in the formation of the layered intrusion is estimated at 2798 ± 17 Ma, based on the U – Th – Pb dating (SHRIMP) of zircons from pegmatitic gabbro. The presence of grains with Palaeo-Mesoarchaean cores among the zircons indicates the contamination of the gabbro with crustal TTG granitoids. Furthermore, zircons, altered hydrothermally in the Palaeoproterozoic, were revealed. Thus, the age dates for the zircons are in good agreement with the relative geological age of the intrusion and the crustal evolution of the Bundelkhand craton. No mafic – ultramafic layered intrusions, similar to the Ikauna layered intrusion, have been reported from other cratons in the Indian Shield, but Keshargaria Swarm dykes of similar age (2800 ± 0.7 Ma) have been described from the Singhbhum craton.

KEYWORDS:

• Archaean
• layered intrusion
• Bundelkhand craton
• mafic-ultramafic

Acknowledgments

The authors also wish to thank Dr Robert J. Stern, Dr Asish Basu and anonymous reviewer for comments that have helped improve the manuscript, as well as G. Sokolov who translated the manuscript. This work continues under a Memorandum of Understanding between Bundelkhand University, Jhansi, India and the Institute of Geology, Karelian Research Centre, RAS, Petrozavodsk, Russia.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/00206814.2024.2361465

Additional information

Funding

The paper has been prepared in the framework of research projects of the Karelian Research Centre, RAS (No. FMEN-2023-0001). The authors wish to thank Alexander Larionov for the SHRIMP-II dating of zircons (CIR VSEGEI, Saint-Petersburg).