Australian-Antarctic breakup and seafloor spreading: balancing geological and geophysical constraints

The motion of diverging tectonic plates is typically constrained by geophysical data from preserved ocean crust. However, constraining plate motions duringcontinental rifting and the breakup process relies on balancing evidence from a diverse range of geological and geophysical observations, often subject to differinginterpretations. Reconstructing the evolution of rifting and breakup between Australia and Antarctica epitomizes the challenges involved in creating detailed modelsof Pangea breakup. In this example, differing degrees of emphasis on and alternative interpretations of offshore geophysical data, in particular magnetic anomaliesand seismic reflection profiles, and onshore geological data, lead to starkly contrasting views of how the continents were configured at the onset of Mesozoic rifting.Here, we critically review reconstructions of rifting and breakup in the light of all available geological and geophysical data, including magnetic anomalies, fracturezones, conjugate crustal domains, amounts of continental extension, continental geology, plate boundary locations, break-up ages and stratigraphy. We identify themost viable plate tectonic reconstructions both with and without the input of the oldest, more controversial magnetic anomaly interpretations, and discuss implicationsfor reconstructions of other margin pairs. Our analysis highlights key discrepancies between reconstructions based solely on geological piercing points, andthose based on a range of constraints. These insights provide a powerful framework for reducing the range of viable models for Australian-Antarctic rifting, andprovide key lessons for future efforts aimed at constraining pre- and syn-rift plate tectonic reconstructions