Accretion history of the Trans-Hudson Orogen in Manitoba and Saskatchewan from paleomagnetism

Lithoprobe's sponsorship has led to the acquisition of paleomagnetic data from similar to 20 units throughout the Paleoproterozoic Trans-Hudson Orogen (THO) of Saskatchewan and Manitoba, essentially the first such data for the region. Discussed summarily in this paper, they provide an initial framework for the THO's tectonic evolution. They show that the Archean Hearne and Superior cratons were at subtropical and subpolar paleolatitudes, respectively, at similar to 1875 Ma, with the Lynn Lake - LaRonge arc midway between them in the Manikewan Ocean. By similar to 1855 Ma, this ocean was still similar to 5500 +/- 700 km wide, and its seafloor was subducting northwestward under the Hearne craton and pericratonic Peter Lake domain margin with the coeval development of an Andean-type continental magmatic arc, the Wathaman-Chipewyan batholith. Between similar to 1855 and similar to 1810 Ma, coalescing apparent polar wander path (APWP) segments record closing of the ocean at a rate of similar to 12 cm/a, trapping and accreting the several separate intervening terranes (Flin Flon, Hanson Lake, Lynn Lake - LaRonge, Rottenstone, and presumably also other THO terranes). From similar to 1815 to similar to 1775 Ma, the assembled terranes drifted as a coherent craton, yielding a stillstand and hairpin in the APWP.