Central/Eastern Indian Bundelkhand and Bastar cratons in the Palaeoproterozoic supercontinental reconstructions: A palaeomagnetic perspective

Abstract

Mafic dykes in the central Indian Bundelkhand and eastern Indian Bastar cratons are potential sources for tracing the location of the Indian shield within Palaeoproterozoic supercontinent reconstructions. A total of 610 oriented core samples were collected from 27 mafic dykes (342 samples) in Bundelkhand craton and 20 dykes (268 samples) in Bastar craton. The characteristic magnetisations identify distinct groups of directions. The derived palaeopoles are integrated with recently reported U–Pb isotopic ages from the Bundelkhand and Bastar cratons and correlated with palaeopoles from the mafic dykes in the Dharwar craton, South India. Characteristic remanence (ChRM) identified in these dykes are classified into (i) steep upward/downward components further sub-grouped as ca. 2.37Ga steep 1 (λ=10.2°S; Ф=75.0°E; A95=18.1° in Bundelkhand and λ=22.3°N; Ф=71.4°E; A95=21.6° in Bastar), component comparable with ca. 2.4–2.45Ga steep 2 group from one dyke in Bundelkhand (λ=14°S; Ф=101°E; A95=26.1°) and one dyke in Bastar (λ=6°N; Ф=113°E; A95=26.5°). A steep component (λ=60.4°N; Ф=45.3°E; A95=9.7° in Bundelkhand and a comparable component λ=49°N; Ф=129°E; A95=15.1° from one dyke in Bastar) is not assigned an age at present. (ii) ca. 2.18Ga shallow easterly and antipodal shallow westerly components (λ=0.4°S; Ф=347°E; A95=21.6° in Bundelkhand and λ=18.0°N; Ф=344.0°E; A95=8.1° in Bastar) and (iii) 1.99Ga shallow northwest and antipodal shallow southeast (λ=57.5°N; Ф=309.0°E; A95=4.7° in Bundelkhand and λ=39°N; Ф=321°E; A95=28° in Bastar). A group (iv) of ∼2.2Ga northeast shallow components (λ=36.0°S; Ф=357.0°E; A95=9.4°) is found only in the Bundelkhand craton. The distinct groups of palaeomagnetic pole determinations from dykes of the Bundelkhand and Bastar craton exhibit a remarkable match with palaeomagnetic poles determined from Precambrian mafic dykes in the Dharwar craton. The close comparison of mafic dyke magnetisations between the cratons suggests close proximity since 2.45–2.5Ga. Models suggesting amalgamation of crustal blocks along the Central Indian Tectonic Zone at 1.8Ga or a 1.0Ga collision along this zone to form Rodinia are untenable. Testing of proposed NeoArchaean-Palaeoproterozoic supercontinent reconstructions showing a north China–India linkage or India's close proximity to Slave craton to form a supercraton ‘Sclavia’ are not supported. Instead, the data are compatible placing India in close proximity to the Yilgarn block of Western Australia.