Abstract The Bastar Craton of India is composed of Archaean nuclei of tonalite–trondhjemite–granodiorite gneisses, enveloped by an older granite–greenstone belt (>3000 Ma) with banded iron formation (BIF), and an auriferous younger granite–greenstone belt with BIF. Available geological, geochemical and geochronological data indicate multiple episodes of orogeny with high-grade metamorphism at 3200–3300, 2600–2700, 2100–2200, 1900–2000, 1800–1850, 1500–1600 and 1400–1450 Ma, and continental rifting and basin development marked by emplacement of mafic dyke swarms at c. 2900 (subalkaline mafic dykes; BD-1A), 2480 (high-Mg mafic dykes; BD-1B), 2100 (Fe–tholeiite dykes; BD-2A), 1880 (Fe–tholeiites dykes; BD-2B), 1776 and 1422 Ma. Associations of extensive bimodal volcanics and riftogenic sediments are found in the Neoarchaean and Palaeoproterozoic basins of the craton. Evidence of Palaeoproterozoic (Huronian) glaciation and associated ‘cap carbonate’ followed by deposition of fine clastics with manganese ore is found in the Palaeoproterozoic Sausar Group. The lithological association of the Sausar Group is comparable to the carbonate–tillite association of the Huronian Supergroup, Snowy Pass Supergroup, Transvaal Supergroup and Turee Creek Group. The geological evolution of the Bastar Craton matches that of Western Australia and South Africa. Such similarities can be analysed to develop a unified Palaeoproterozoic assembly for these provinces.

Abstract It is likely that Archaean cratons of Laurentia had different palaeogeographic histories prior to their amalgamation. New palaeomagnetic, geochronological and geochemical evidence supports a reconstruction of the Wyoming craton adjacent to the southern margin of the Superior craton at 2.16 Ga, before rifting ( c. 2.1–2.0 Ga) and eventual reamalgamation after the Hudsonian Orogeny ( c. 1.8 Ga). U–Pb ages (TIMS on baddeleyite) from five dykes yield two groups of ages at c. 2164 and 2155 Ma. The younger group of ages defines the Rabbit Creek swarm at 2161–2152 Ma and precisely dates its palaeomagnetic pole. Two large and differentiated dykes (>100 m) in the Bighorn and Wind River uplifts are geographically related to the Rabbit Creek swarm but have slightly different orientations and yield slightly older ages at 2171–2157 Ma. These dykes may be parts of a single intrusion (the ‘Great Dyke of Wyoming’) that spans over 200 km between uplifts, possibly representing a different magmatic event. This older event does not have enough distinct intrusions to provide a correctly averaged palaeomagnetic pole, but correlates with magmatism in the Superior craton and has a palaeomagnetic remanence comparable to the Rabbit Creek dykes. With minor tilt corrections, the palaeomagnetic data from the Rabbit Creek swarm and Powder River–South Pass dykes support a reconstruction of the southeastern Wyoming craton against the southern Superior craton. This fit juxtaposes the Palaeoproterozoic Huronian and Snowy Pass Supergroups along two passive margins that experienced a prolonged period of mafic magmatism (>100 myr) and rift basin development. Although there are slight geochemical variations across the Rabbit Creek swarm, all dykes fit into two distinct groups that are independently dated and internally consistent. Supplementary material: Supporting figures and locality tables are available at www.geolsoc.org.uk/SUP18824