Paleomagnetism and U-Pb geochronology of diabase dyke swarms of Minto block, Superior Province, Quebec, Canada

Abstract

In the first collaborative study of paleomagnetism and precise U-Pb geochronology in the Minto block of the Superior Province, mafic dyke swarms with three widely divergent paleomagnetic signatures and isotopic ages have been identified. The 2505 ± 2 Ma Ptarmigan dykes trend north to northeast and have a virtual geomagnetic pole at 42°S, 220°E, similar to that of 2473-2446 Ma Matachewan dykes of the southern Superior Province. The ca. 2230 Ma Maguire dykes trend west to northwest and yield a paleopole at 9°S, 267°E, similar to those for 2216+8-4 Ma Senneterre dykes and 2217-2210 Ma Nipissing sills of the southern Superior and Southern provinces, respectively. The 2209 ± 1 Ma Klotz dykes trend west-northwest, but do not carry a consistent magnetization direction. Finally, 1998 ± 2 Ma Minto dykes of west-northwest to northwest trend, identical in age to the 1998 Ma ± 2 Ma Purtuniq ophiolite of the Cape Smith Belt, have a paleopole at 38°N, 174°E. The similarity of paleopoles for the ca. 2.23-2.21 Ga Maguire dykes of the Minto block, Senneterre dykes of the southern Superior, and Nipissing sills of the Southern Province demonstrates that these regions were in their present relative latitudes and orientations at that time. Likewise, the similarity of the Ptarmigan virtual geomagnetic pole and the Matachewan paleopole suggests little relative latitudinal movement or rotation of the two regions since ca. 2.5 Ga. The Maguire, Senneterre, and Klotz dykes form a roughly radiating pattern and may represent one quadrant of a giant radiating dyke swarm centred southeast of Ungava Bay, whose focus marks the location of a mantle plume responsible for ca. 2.22 Ga breakup along the eastern margin of the Superior Province. If so, the coeval Nipissing sills that intrude sedimentary rocks of the Huronian Supergroup of the Southern Province may have been fed laterally by Senneterre dykes from the Ungava plume centre.

Interconnected sills and inclined sheet intrusions control shallow magma transport in the Ferrar large igneous province, Antarctica

“…Magma transport via giant dike swarms within the basement is a feasible explanation (Fleming et al, 1997;Elliot et al, 1999;Elliot and Fleming, 2008); the elongate distribution is consistent with observations of giant dike swarms elsewhere, and these swarms are known to feed sill complexes over long distances (>1500 km from source; Ernst and Buchan, 1997;Buchan et al, 1998). In this case, a giant dike swarm was emplaced laterally from a source in the Weddell Sea region (Elliot et al, 1999;Leat, 2008).…”

Paleomagnetism of the Amazonian Craton and its role in paleocontinents

“…1). Superior Craton (Su) is constrained using the Minto dykes pole (Buchan et al 1998, Evans & Halls 2010. Superior (Su) and Slave (S) relative positions are the same proposed by Mitchell et al (2014) following paleomagnetic data.…”

U-Pb ID-TIMS age of the Tiksheozero carbonatite: expression of 2.0 Ga alkaline magmatism in Karelia, Russia

“…Younger (1980-1950 Ma) mafic activity is represented by the Onega continental flood basalts in Karelia, possibly the suggested extension of the Central Lapland greenstone belt into the Karasjok belt in northern Norway [30,31] and the Horsmanaho and Huutoniemi gabbros from the Outokumpu ophiolite, Jormua ophiolite and Koli-Kalimo mafic dyke swarm in Finland [32][33][34][35]. In Laurentia these episodes correspond to formation of the Portuniq ophiolite, granodiorite and rhyolite of the Povungnituq Group, and the Minto and part of the Scourie dyke swarms [36][37][38][39] Most of these events can be related to crustal extension and rifting, some rifts probably developing into oceanic basins such as the Pechenga-ImandraVarzuga Ocean [40] The Onega continental flood basalts have been interpreted as representing the product of a mantle plume [31].…”