The Australian Antarctic plate boundary is primarily a divergent boundary.
This boundary is where the Australian Plate and the Antarctic Plate are moving away from each other. As these tectonic plates separate, magma rises from the mantle to fill the gap, creating new oceanic crust. This process is most commonly observed along mid-ocean ridges, such as the Macquarie Ridge, which underlies part of the boundary between these two plates.
Additionally, there are segments of transform boundaries within the Australian Antarctic plate boundary. These sections occur where the two plates slide past each other horizontally. This combination of divergent and transform characteristics is what makes the Australian Antarctic plate boundary particularly interesting in the study of plate tectonics.