LONG-LIVED EVOLUTION OF BOUNDING FAULTS TO THE GLENNIE DOMAIN, TRANS-HUDSON OROGEN, SASKATCHEWAN

Faults bounding the Glennie Domain within the Early Proterozoic Trans-Hudson Orogen have a complex history that began nearly 2 billion years ago and continued until at least the Devonian. Geophysical profiling has demonstrated that Archean rocks identified in structural windows beneath allochtonous Early Proterozoic thrust sheets form a large, contiguous Archean continental fragment (Sask Craton) underlying the center of the orogen between the bounding Rae-Hearne and Superior Cratons. Structures along the western margin of the Glennie Domain document the evolution of orogen from initial convergence, ductile nappe emplacement, and transpressional doming at high grade (Guncoat and Nistowiak Gneisses) between 1.837-1.809 Ga (U-Pb zircon). Subsequent to the peak of metamorphism at ca. 1.810 Ga (U-Pb zircon), isotopic closure of titanite occurred by 1.790-1.772 Ga. Late granites and pegmatites were intruded at 1.770-1.762 Ga (U-Pb monazite and allanite), often into vertical, NE-trending, greenschist facies faults that parallel the Stanley Fault, the western boundary of the Glennie Domain. On-going study of apatite fission tracks from the Nistowiak and Iskwatikan lakes area has yielded ages of 375+/-45 Ma and 385+/-55 Ma. This confirms earlier work recognizing late Ordovician - Devonian reactivation of the eastern boundary of the Glennie Domain along the Tabbernor Fault system. The Tabbernor system also displays a complicated early ductile history upon which brittle structures are superimposed. This data indicates the boundaries of the Sask Craton continued to influence cratonic adjustment and orogenic uplift at least into the late Paleozoic and that movement was focussed along Early Proterozoic ductile structures.