Late Archean sedimentary basins in the northeastern Superior Province, Canada: Plume-generated crustal tears or syn-convergent accretionary belts?

[Display omitted] •New U–Pb detrital zircon ages are reported from the NE Superior Province.•The dating identified 3 sources, old cratonic, TTG gneisses, and synsedimentary plutons.•Most of the maximum depositional ages fall within a time span of ca. 2710–2685 Ma.•The ages suggest a short time lag from deposition to deformation and metamorphism.•Basins developed in a compressive setting of an Alaskan-type accretionary orogen. This study reports new U–Pb detrital zircon ages determined using the laser ablation inductively coupled plasma mass spectrometry (LA ICP-MS) from the greenstone-dominated and metasedimentary belts of the northeastern Superior Province, Québec, Canada. The U–Pb ages were obtained along a ca. 300 km long transect that traverses the Opinaca and Némiscau belts from north to south across their strike, but also traverses supracrustal volcano-sedimentary units that underlie these belts or are infolded and/or imbricated within the gneissic basement. The zircon age data, supported by trace element and Nd isotope geochemistry, point to three main sediment sources: (1) ‘old cratonic’ with ages >3 Ga (likely coming from the northerly Minto block), (2) local gneissic (TTG) basement with ages scattered at around 2.8 Ga, and (3) plutons and/or their volcanic counterparts only shortly preceding, or being broadly coeval with, the sediment deposition. The depositional ages range from 2730 ± 11 Ma to 2661 ± 11 Ma, but in most cases fall into a narrower age interval between ca. 2710 Ma and ca. 2685 Ma. In agreement with the previous detrital zircon geochronology studies, our new ages corroborate a short time span of zircon crystallization, exhumation, erosion and deposition, burial, and subsequent deformation and metamorphism, a pattern characteristic of modern arc domains. The depositional ages also exhibit a remarkable systematic spatial variation with latitude, younging southwards along the sampled transect. The southward younging of deposition and plutonism was previously explained as a result of outwardly propagating extension (crustal tearing) and magmatic underplating above mantle upwelling in a non-plate-tectonic regime, implying that the observed compressional deformation and metamorphism was superposed on an extensional phase. On the contrary, combining the detrital zircon ages from the metasedimentary belts with the previously published structural information from coeval plutons, we suggest that the basin development and sediment deposition t