Proterozoic rotation of the Peter Lake domain in the Trans-Hudson orogen of Saskatchewan, Canada, deduced from paleomagnetism

Abstract

Abstract The Peter Lake domain is a northeast-trending, 200 km long, cigar-shaped terrane. On its southeast side is the 1854±11 Ma Wathaman batholith that marks the suture zone for the juvenile terranes of the Trans-Hudson orogen (THO), and on its northwest side is the Wollaston fold belt that defines the margin of the Archean Slave-Rae-Hearne (SRH) craton. Two well-defined remanent magnetization components are carried by hematite, magnetite and pyrrhotite in a range of metamorphic rock types. The A component was probably acquired during + the D1 regional metamorphic event at ∼ 1869 Ma and gives a direction of D = 302°, I = −40° (α95 = 10°, k = 16, N = 15). Its pole position at 3°N, 52°W (dp = 7°, dm = 12°) locates the Peter Lake domain along the margin of the SRH craton at the time of metamorphism and was later rotated 32° ± 14° counterclockwise, probably when the abutting southwestern arm of the Wathaman batholith was similarly rotated during oroclinal deformation. The B component is found preferentially in the Parker Lake gneisses but is also found in minor shear zones in the Peter Lake complex and Wathaman batholith, and it replaces the A component by remagnetization. B has a direction of D = 92°, I = 83° (α95 = 8°, k = 19, N = 20) that gives a pole at 54°N, 80°W (dp = 15°, dm = 15°). The B remanence is thought to have been acquired at about 1780 Ma during the D3 shearing event. This event produced the Needle Falls and Parker Lake shear zones that separate the Peter Lake domain from the Wollaston fold belt and Wathaman batholith, respectively. The B component likely defines the end of the Trans-Hudson orogenic event during which the 5000 km wide Manikewan ocean closed. Thorough evaluation of the Andean collisional model for the THO will require much more paleomagnetic data.