UPb geochronology and tectonic development of the southern flank of the Kisseynew Domain, Trans-Hudson Orogen, Canada

Abstract

The southern flank of the Kisseynew Domain, northern Manitoba, underwent polyphase deformation and metamorphism during the Palaeoproterozoic Trans-Hudson Orogen, and represents a lithological, metamorphic and structural transition from greenschist-grade volcano-plutonic rocks of the Flin Flon Domain to amphibolite-grade paragneisses of the central Kisseynew Domain. The timing of geological events has previously been constrained using widely dispersed sample sites, but this study has integrated UPb geochronology with detailed lithological and structural mapping in the Cleunion Lake area. Pink gneisses, interpreted as Missi supracrustal rocks, were deposited after 1855 Ma, but prior to ∼ 1835 Ma, and thus are similar in age to fluvial sedimentary rocks in the lower-grade Flin Flon Domain. All the zircons in the pink gneisses appear to be inherited, or resorbed during later amphibolite-grade metamorphism, and a late Archaean component is also indicated. Corundum-bearing gneisses in the Missi Group and leucosomes in Burntwood River Group rocks are deformed by F 1 and are indicative of an early high- T, low- P metamorphic event (M 1) that may have been synchronous with the intrusion of 1835 to 1827 Ma intrusions, and related to regional crustal extension. The above rocks are folded during a continuous compressional deformation event (D 2) related to terminal collision between the Palaeoproterozoic rocks of the Trans-Hudson Orogen and the Superior Province. Three main fold generations (F 1, F 2, F 3) have been identified, which occurred during D 2. A 1818 Ma granitic vein is approximately synchronous with F 2 and peak metamorphic (M 2) conditions in the Cleunion Lake area. Cooling, uplift, and intrusion of pegmatites during F 3 at ∼ 1800 Ma provides a time limit on the waning stages of compressional deformation. The main phase of compressional deformation (D 2) in the southern flank of the Kisseynew Domain thus lasted for about 30 million years.