Three high-resolution vibroseis reflection profiles were acquired across the Paleoproterozoic Huronian Supergroup (2.5-2.2 Ga) of the Canadian Shield, in the vicinity of the Temagami Lake magnetic anomaly, one of the largest positive magnetic anomalies in North America. The Supergroup, formed as a passive margin sequence and composed of volcanic and sedimentary rocks, unconformably overlies Archean rocks of the Superior Province. Quality seismic images, obtained through innovative pseudo-3D seismic processing and constrained by lithological data from deep boreholes, reveal a 20-km-wide early Proterozoic rift basin beneath a thick cover of metasidiments, one of the oldest well-preserved rift basins on Earth.