Structural studies are a significant but frequently neglected tool to improve our understanding of early-Earth tectonic processes and geodynamic settings. Two end-member styles of Archean crustal deformation are generally termed “dome-and-keel” and “transpressional belts” (Choukroune et al., 1997). Dome-and-keel domains were shaped by the juxtaposition of rising granite batholiths and sinking denser greenstones, with a tectonic style dominated by gravitational instabilities and body forces. In contrast, transpressional belts are generally interpreted to reflect accretionary processes associated with production of juvenile crust along ancient crustal boundaries. The Yilgarn Craton mostly exposes Meso- to Neoarchean granite–greenstone terranes that preserve evidence of large-scale tectonomagmatic events of Neoarchean age. In this context, recent structural studies suggest that large-scale structures that can be related to the two end-member tectonic styles outlined above are preserved in distinct parts of the craton. Dome-and-keel domains are exposed in the Yalgoo area, near the western end of the craton, reflecting periods of granitic diapirism that took place during pre-orogenic periods of prevailing lithospheric extension and tectonic quiescence (Zibra et al., 2020). In contrast, the rest of the craton exposes a network of dominantly north-striking and steeply-dipping shear zones that developed during the 2730–2660 Ma Yilgarn Orogeny (Zibra, 2020). The onset of the orogeny reflects the collision between the westernmost Narryer Terrane with the rest of the craton, postdating a long period of lithospheric convergence and associated subduction episodes that are recorded in the structural, geochemical, geophysical and metamorphic record (Zibra et al., 2022). Although several of the orogenic high-strain zones have been the subject of publications, a craton-wide perspective on the dominant tectonic style is currently missing, and represents one of the main goals of this contribution. Here, I present a statistical evaluation of craton-wide structural data (n=1590) collected during the last 15 years. Furthermore, I combine this extensive structural dataset with stratigraphic and geochemical data, in order to gain fundamental insights into the tectonomagmatic evolution of the Yilgarn Craton, and into Archean tectonics in general. 

Reference(s)

Choukroune, P., Ludden, J. N., Chardon, D., Calvert, A. J., & Bouhallier, H. (1997). Archaean crustal growth and tectonic processes: a comparison of the Superior Province, Canada and the Dharwar Craton, India. Geological Society, London, Special Publications, 121(1), 63–98. https://doi.org/10.1144/GSL.SP.1997.121.01.04

Zibra, I. (2020). Neoarchean structural evolution of the Murchison Domain (Yilgarn Craton). Precambrian Research, 343, 105719. https://doi.org/10.1016/j.precamres.2020.105719

Zibra, I., Kemp, A. I. S., Smithies, R. H., Rubatto, D., Korhonen, F., Hammerli, J., Johnson, T. E., Gessner, K., Weinberg, R. F., Vervoort, J. D., Martin, L., & Romano, S. S. (2022). Greenstone burial–exhumation cycles at the late Archean transition to plate tectonics. Nature Communications, 13(1). https://doi.org/10.1038/s41467-022-35208-2

Zibra, I., Lu, Y., Clos, F., Weinberg, R. F., Peternell, M., Wingate, M. T. D., Prause, M., Schiller, M., & Tilhac, R. (2020). Regional-scale polydiapirism predating the Neoarchean Yilgarn Orogeny. Tectonophysics, 779, 228375. https://doi.org/10.1016/j.tecto.2020.228375