A crustal radially anisotropic shear-wave velocity model of Northwestern Australia

The aim of this study is to investigate the crustal architecture of northwestern Australia during the Precambrian, encompassing the Pilbara Craton, the Canning Basin, and the Kimberley Craton. This region played a pivotal role in the formation of proto-Australia during the Proterozoic. However, the exact mechanisms and locations of assembly beneath the thick Phanerozoic Canning Basin remain heavily debated due to insufficient detailed regional crustal structural information. By developing a radially anisotropic shear wave velocity model of the regional crust, we directly visualize the deformation fabrics of the entire crust, which can be correlated with seismic anisotropy. Through spatial correlation with surface geology, we deduce potential ancient deformation scenarios unique to each crustal domain. Our new anisotropy model, characterized by rapidly changing and spatially distinct anisotropy patterns, reveals several significant findings. Subvertical deformation is associated with the northeast margin of the exposed Pilbara Craton and the western margin of the Kimberley basement, indicating collisional deformation in these Archean crustal segments. Strong horizontal deformation is inferred east of the Fenton fault in the Canning Basin, aligning with the multiple stages of extensional processes that formed the basin. This extensional signal extends into the west Lamboo Province of the Kimberley Craton. In the western Canning Basin, the Percival Lake Province, identified by its distinctive seismic, age, and isotopic characteristics in recent studies, lacks a clear extensional signal. Instead, two sub-crustal domains are favored, exhibiting opposing deformation fabrics. The newly revealed regional anisotropic architecture provides insights into the complex amalgamation processes between the Pilbara and Kimberley Cratons, as well as significant basin deformations following cratonization. Our study demonstrates that radial anisotropy offers direct lithospheric constraints, enhancing our understanding of the formation and evolution of Precambrian continents in concealed regions.