Testing the Paleogeography of Late Archean Supercraton Superia using Pre-Breakup 2.51-1.98 Ga dyke and Sill Provinces – with a Focus on the Relationship Between the Karelia-Kola and Superior Cratonic Fragments

• Main Author: Davey, Sarah
• Format: Thesis
• Language: unknown
• Published: 2020
• Subjects: Canada; Maguire; karelia*
• Online Access: https://curve.carleton.ca/f8164cb7-9bd3-43d5-a49a-32510a5849a1; https://doi.org/10.22215/etd/2020-14109; https://ocul-crl.primo.exlibrisgroup.com/permalink/01OCUL_CRL/j2o5om/alma991022781827205153

Archean cratons are dispersed crustal fragments derived from larger ancestral landmasses. Their individual and combined study in paleogeographic reconstructions reveal details relevant to understanding larger Archean tectonic systems. Canada's Superior craton is considered the central piece of the late Archean Superia supercraton paleogeographic reconstruction that also includes the Karelia-Kola (Finland/Russia), Wyoming (USA), and Hearne (Canada) cratons. The relationship between Superior and Karelia-Kola is of interest because the position of the Karelia-Kola craton within the context of the Superia reconstruction is not fully resolved. Dyke swarm correlations based on age and geometry indicate that Karelia-Kola and Superior were 'nearest-neighbours', yet paleomagnetic studies disagree. However, these data are complicated due to multiple metamorphic overprints, and are limited by a lack of high-precision U-Pb ages. The focus of this study is to test the correlation between the Karelia-Kola and Superior cratons by integrating U-Pb geochronology, whole-rock major, trace element and Sm-Nd isotope geochemistry, and dyke swarm geometry. These methods confirm the occurrence of sharply timed large igneous provinces (LIP) in Karelia-Kola correlated to Superior using geochronology, test whether the magmas were from a common source, and refine the paleogeographic Superia reconstruction by incorporating regional dyke trends. This study presents nine ages from dykes and sills that confirm LIP correlations between the Karelia-Kola and Superior cratons at ca. 2.40 Ga, 2.22 Ga, 2.11 Ga and 1.98 Ga, and three ages at ca. 2.32 Ga confined to Karelia-Kola. Geochemical studies were completed on mafic magmatic events at ca. 2.22 Ga and 2.11 Ga. The evaluation of 2.22 Ga dykes and sills confirms that the Senneterre and Maguire dykes are compatible feeders to the Nipissing sills (Superior) and that the Karjalitic sills (Karelia-Kola) are not their direct continuation. At 2.11 Ga, mafic dykes and sills from Superior, Karelia-Kola, Wyoming and Hearne cratons were generated from two mantle end-member sources that mixed together and assimilated a crustal component. In support of a nearest-neighbour connection between the Karelia-Kola and Superior cratons, the integration of U-Pb geochronology, geochemistry and dyke trends provide controls for a refined configuration of the Karelia-Kola craton within the Superia supercraton paleogeographic reconstruction.