Geochemical mapping of lithospheric architecture disproves Archean terrane accretion in the Yilgarn craton

The basement of Mesoarchean to Neoarchean greenstone basins in the Yilgarn craton is composed of fragments of evolved crust up to 3.7 Ga old. New cratonwide geochemical and isotopic data with unparalleled spatial resolution image a NE-to ENE-trending architec-ture in pre-2.73 Ga crust. These trends cannot be reconciled with plate-tectonic models, as they persist across younger NNW-striking structural fabrics, including a proposed suture previously interpreted to result from exotic terrane accretion. Our results suggest that, in spite of their substantial strike length, the NNW-trending structures have limited horizontal displacement and, although important for understanding regional geology, may be a geo-dynamically insignificant overprint of the primary ENE-trending architecture. We propose that these greenstone provinces or belts include individual basins formed in rifts with loca-tion, size, and orientation influenced by the interaction between basement fragments and regional crustal extension.

Automated summary

This study reveals the existence of evolved crust fragments up to 3.7 billion years old in the basement of Mesoarchean to Neoarchean greenstone basins in the Yilgarn craton. The new geochemical and isotopic data show a NE-to ENE-trending architecture in the pre-2.73 Ga crust, which challenges plate-tectonic models. The results suggest that the NNW-trending structures, although important in regional geology, may be an insignificant overprint of the primary ENE-trending architecture.