Abstract The Australian continent records c. 1860–1800 Ma orogenesis associated with rapid accretion of several ribbon micro-continents along the southern and eastern margins of the proto-North Australian Craton during Nuna assembly. The boundaries of these accreted micro-continents are imaged in crustal-scale seismic reflection data, and regional gravity and aeromagnetic datasets. Continental growth ( c. 1860–1850 Ma) along the southern margin of the proto-North Australian Craton is recorded by the accretion of a micro-continent that included the Aileron Terrane (northern Arunta Inlier) and the Gawler Craton. Eastward growth of the North Australian Craton occurred during the accretion of the Numil Terrane and the Abingdon Seismic Province, which forms part of a broader zone of collision between the northwestern margins of Laurentia and the proto-North Australian Craton. The Tickalara Arc initially accreted with the Kimberley Craton at c. 1850 Ma and together these collided with the proto-North Australian Craton at c. 1820 Ma. Collision between the West Australian Craton and the proto-North Australian Craton at c. 1790–1760 Ma terminated the rapid growth of the Australian continent.

Abstract Seismic reflection and refraction profiles, and potential field data, complemented by crustal-scale gravity modelling, plate reconstructions and well cross-sections are used to study the evolution of the South Segment of the South Atlantic conjugate margins. Distinct along-margin structural and magmatic changes that are spatially related to a number of conjugate transfer systems are revealed. The northern province, between the Rio Grande Fracture Zone and the Salado Transfer Zone, is characterized by symmetrical seawards-dipping reflections (SDRs) and symmetrical continent–ocean transitional domain. The central province, between the Salado Transfer Zone and the conjugate Colorado–Hope transfer system, is characterized by along-strike tectonomagmatic asymmetry. The Tristan da Cunha plume, located on the central province of the South Segment, may have influenced the volume of magmatism but did not necessarily alter the process of rifted margin formation. Thus implying that, apart from voluminous magmatism, the extensional evolution of the central province of the South Segment may have much in common with ‘magma-poor’ margins.