Australian-Antarctic breakup and seafloor spreading: balancing geological and geophysical constraints
Williams, SE and Whittaker, JM and Halpin, JA and Muller, RD, Australian-Antarctic breakup and seafloor spreading: balancing geological and geophysical constraints, Earth Science Reviews, 188 pp. 41-58. ISSN 0012-8252 (2019) [Refereed Article]
The motion of diverging tectonic plates is typically constrained by geophysical data from preserved ocean crust. However, constraining plate motions during
continental rifting and the breakup process relies on balancing evidence from a diverse range of geological and geophysical observations, often subject to differing
interpretations. Reconstructing the evolution of rifting and breakup between Australia and Antarctica epitomizes the challenges involved in creating detailed models
of Pangea breakup. In this example, differing degrees of emphasis on and alternative interpretations of offshore geophysical data, in particular magnetic anomalies
and 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, fracture
zones, conjugate crustal domains, amounts of continental extension, continental geology, plate boundary locations, break-up ages and stratigraphy. We identify the
most viable plate tectonic reconstructions both with and without the input of the oldest, more controversial magnetic anomaly interpretations, and discuss implications
for reconstructions of other margin pairs. Our analysis highlights key discrepancies between reconstructions based solely on geological piercing points, and
those based on a range of constraints. These insights provide a powerful framework for reducing the range of viable models for Australian-Antarctic rifting, and
provide key lessons for future efforts aimed at constraining pre- and syn-rift plate tectonic reconstructions.