Work

Insights Into the Archean to Phanerozoic Evolution of Southwest Australia From Seismic Ambient Noise Tomography

Year: 2025

Type: article

Abstract: The tectonic evolution of southwest Australia, including Archean cratonization and multiple episodes of Proterozoic to Phanerozoic supercontinental assembly and breakup, remains debated, in part due to previously poorly constrained crustal structures. This study presents a new 3‐D shear wave velocity (Vs) model in the crust and uppermost mantle of southwest Australia using seismic ambient noise tomography. We utilize new data collected from 27 broadband stations deployed in the region from 2020 to 2023, augmented by reprocessed data from nearby permanent and previous temporary stations. The Vs model highlights distinct crustal structures associated with the Archean Yilgarn Craton, its fringing Proterozoic Pinjarra Orogen and Albany–Fraser Orogen, Phanerozoic Perth Basin, and the long‐lived Darling Fault. It documents the region's complex evolution from Archean and Proterozoic crustal growth and reworking events to Phanerozoic continental rifting and breakup. We also identify a high‐velocity (3.8–4.2 km/s) zone in the middle‐to‐lower crust (>10 km in depth) along the southwestern edge of the Yilgarn Craton but east of the Darling Fault, a structural feature imaged for the first time. This anomaly is likely related to magmatic underplating processes during continental breakup and rifting localized on a pre‐existing weak zone. The imaged heterogeneity in the deep crust supports the geochemistry‐based models of deep‐rooted ENE‐trending structures across the Yilgarn Craton, which challenges the traditional terrane‐accretion model for Archean craton formation. It also implies that the tectonomagmatic processes that have shaped craton margins can affect larger parts of the continental crust at depth compared to what is apparent at Earth's surface.

Source: Journal of Geophysical Research Solid Earth

DOI: 10.1029/2025jb031274