Stranding continental crustal fragments during continent breakup: Mantle suture reactivation in the Nain Province of Eastern Canada

Earth's continental crust has evolved through a series of supercontinent cycles, resulting in a patchwork of Archean cores surrounded by terranes, fragments, and slivers of younger crustal additions. However, the dispersal (and/or stranding) of continental fragments dur-ing breakup is not well understood. Inherited structures from previous tectonic activity may explain the generation of continental terranes by controlling first-order deformation dur-ing rifting. Here, we explored the influence of lithospheric deformation related to ancient orogenesis, focusing on the impact of the Torngat orogen in the genesis of the Nain Province continental fragment in Eastern Canada. We present three-dimensional continental exten-sion models in the presence of an inherited lithospheric structure and show that a narrow continental terrane could be separated and stranded by deep lithospheric scarring. The results show that continental terranes formed by this method would be limited to a width of 100-150 km, imposed by tectonic conditions during continental suturing. The findings have broad implications, demonstrating an original theory on the fundamental geologic problem of terrane generation and continent breakup.

Automated summary

Earth's continental crust has gone through supercontinent cycles, leaving behind ancient cores and younger crustal additions. However, the mechanism of continental fragment dispersal during breakup is not well understood. Inherited structures from previous tectonic activity may play a role in the generation of continental terranes. By studying the Torngat orogen and the Nain Province continental fragment in Eastern Canada, researchers have shown that deep lithospheric scarring can separate and strand narrow continental terranes, with a width limited by tectonic conditions during continental suturing. This finding has important implications for understanding terrane generation and continent breakup.