Age and origin of the Jan Lake Complex: a glimpse at the buried Archean craton of the Trans-Hudson Orogen

The largely buried Sask Craton is a continental fragment or microcontinent that collided with and underthrust the Paleoproterozoic Flin Flon - Glennie protocontinent along the Pelican Decollement Zone at 1840-1830 Ma. Rocks o f the Sask Craton are exposed in three tectonic windows. Those of the Pelic an Window have been named the Jan Lake Complex and comprise greater than or equal to 2960 Ma are-derived leucocratic orthogneisses, migmatitic paragne isses, and a tholeiitic, within-plate igneous suite comprising 2488 Ma dior itic to gabbroic rocks and 2450 Ma enderbitic and charnockitic rocks includ ing the Sahli Granite. Ages of ca. 2450 Ma are also common from the other t wo tectonic windows to the Sask Craton, suggesting that emplacement of the igneous suite was widespread and perhaps part of the coeval Matachewan Igne ous Event. The absence of rocks in the greater than or equal to 2960 and ca . 2450 Ma age ranges on both the adjacent Superior and Rae-Hearne cratonic margins makes it improbable that the Sask Craton was derived by simple frag mentation without large-scale tectonic transport. The overthrust Paleoprote rozoic rocks represent a high-grade northwestern extension of the Flin Flon volcanic belt and include 1856 Ma leucotonalite and 1843 Ma quartz monzodi orite. An 1830 Ma suite of homogeneous, calc-alkaline enderbitic rocks, whi ch intrude Burntwood semipelitic migmatites throughout the Kisseynew Domain , has also been emplaced in mylonites of the Pelican Decollement Zone. Zirc on and monazite ages in the 1812-1803 Ma range record a high-grade metamorp hic event that resulted from collision between the Sask Craton and Flin Flo n - Glennie Complex.