Disruption and localization of sediment pathways by continental extension: Detrital-zircon provenance change from upper Triassic to lower Jurassic in the northern Sverdrup Basin, Nunavut

Constraints on the tectonic setting of the upper Triassic to lower Jurassic in the Sverdrup Basin can be elucidated from detrital-zircon U-Pb ages. During the Triassic, there was a dual provenance system into sedimentary basins along the western and northern margins of Laurentia. One of the sediment sources was from an extra-basinal igneous source of Permian-Triassic zircon while the other source was recycled sediment eroded from older sedimentary basins. The Heiberg Formation/Group was deposited during a period of significant siliciclastic sedimentation into the basin from the upper Triassic to the lower Jurassic and comprises three members: Romulus, Fosheim and Remus. Previous work has interpreted that the Carboniferous-Permian-Triassic detrital zircon had stopped reaching the northern part of the Sverdrup Basin by deposition of the upper Heiberg Formation (lower Jurassic). New detrital-zircon age analyses from samples along the northern part of the basin spanning different horizons in the Heiberg Formation show that the typical extra-basinal signature, with abundant Carboniferous-Permian-Triassic ages, was no longer recorded during the initial deposition of the Fosheim Member during the latest Triassic. Previously published basin analysis from the Sverdrup Basin interprets syn-Jurassic extensional faults and so we relate the provenance change to the onset of extension. It is interpreted that the Sverdrup Basin transitioned from a basin that received sediment from a northern extra-basinal igneous source during deposition of the Romulus Member to an extensional basin by the deposition of the Fosheim Member in the latest Triassic, as the northern sediment source was interrupted by intervening extensional basins of the proto-Amerasia Basin.