Geochemical mapping of lithospheric architecture disproves Archean terrane accretion in the Yilgarn craton
R.H. Smithies, Klaus Gessner, Yongjun Lu, Christopher L. Kirkland, Tim Ivanic, Jack R. Lowrey, D.C. Champion, Jyotindra Sapkota, Quentin Masurel, Nicolas Thébaud, R. Quentin de Gromard
Abstract
Abstract 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 architecture 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 geodynamically insignificant overprint of the primary ENE-trending architecture. We propose that these greenstone provinces or belts include individual basins formed in rifts with location, size, and orientation influenced by the interaction between basement fragments and regional crustal extension.