COMPARING THE PHANEROZOIC THERMAL EVOLUTION OF THE PROTEROZOIC TRANS-HUDSON OROGEN WITH THAT OF THE ARCHEAN SUPERIOR AND SLAVE CRATONS, CANADA

Episodes of kilometer-scale Phanerozoic burial and erosion are increasingly documented in Archean cratons, providing key insights into the later part of their evolution. Previous apatite (U-Th)/He (AHe) work in the Slave and Superior cratons of the Canadian Shield document a spatially variable burial and erosion history. Between these cratons and deeper in the continental interior lies the Trans-Hudson Orogen (THO), one of the world’s largest Paleoproterozoic orogens that records the 1.9-1.8 Ga collision of the Hearne and Rae cratons with the Superior craton. Here we present new AHe data across the western THO in Manitoba both to compare with our previous results across Archean cratonic areas and to evaluate the extent to which the contrasting Archean versus Proterozoic lithospheric architecture may influence the Mesoproterozoic to Phanerozoic history. The AHe dates range from 439 ± 26 to 535 ± 15 Ma and lack systematic variation across the Superior boundary zone separating the THO and Superior craton. The absence of appreciable Mesoproterozoic to Phanerozoic metamorphic or igneous activity suggest that burial and exhumation induced the Early Paleozoic AHe dates. Deposition in the Athabasca basin at the northern edge of the THO suggest the region was likely near the surface by ~1,650 Ma, and deposition in the Williston and Hudson Bay basins suggest it was near the surface again at ~520-440 Ma. Thus, burial and erosion of the THO may have occurred between these two surface constraints. The AHe dates from the THO are older than the majority of the results from the Slave and Superior craton, suggesting less burial and erosion here, due either to its distal location from plate boundaries or a lithospheric control on the surface history here.