Crustal structure of the metasedimentary Kisseynew domain and bounding volcanic–plutonic domains, Trans-Hudson orogen, Canada

Abstract

The Kisseynew domain (KD) is the largest component of the Paleoproterozoic Trans-Hudson orogen (THO) in Saskatchewan and Manitoba. It is bounded to the north by the Lynn Lake – Leaf Rapids (LL-LR) domain and to the south by the Glennie – Flin Flon (G-FF) complex. The THO was the focus of one of the study areas of Lithoprobe, Canada’s national Earth science research project (1984–2005). To further investigate the crustal structure of the KD and its bounding domains, this study reprocesses reflection line S3a across its northern boundary, analyses four 2.5-D gravity profiles, carries out 3-D gravity inversions for two areas, and replicates results from reflection lines 7 and 10 across the southern boundary of the KD. The reprocessed seismic section enhances the continuity of reflections within the crust. The reflectivity is representative of the complex tectonic development of the boundary zone and clearly identifies a subsurface deformation zone consistent with the boundary. The reflection section also shows that a lower plate (at about 30 to 50 km depth), interpreted as remnant lower crust of the G-FF complex, extends 30 km further northward than in the original section. Lines 7 and 10 illustrate the complex nature of the transition from the KD to the G-FF complex. The gravity analyses show that the variability and complexities of the boundary region between the LL-LR domain and KD, and the G-FF complex and KD, as indicated by the geological and Bouguer gravity maps, extend at depth throughout the crust.