Cause and evolution of intraplate orogeny in Australia

Intraplate orogeny remains an enigmatic process in terms of plate tectonics. Regional continental stress fields agree well with stress orientations predicted by the main forces driving and resisting plate motion. However, regional continental stress fields fail to explain major localized compressive plate deformation in continental interiors far away from plate boundaries. Global or plate-wide intraplate stress models typically assume a laterally homogeneous plate rheology and are confined to modeling the present, without addressing the antiquity of the current stress field. An understanding of intraplate stress and deformation requires the linking of spatial variations in continental rheology with time-dependent plate geometry and driving forces. Here we demonstrate how the complex interplay between juxtaposed weak and strong geological provinces and changes in far-field plate boundary forces has caused intraplate orogenesis and tectonic reactivation in southeastern Australia during the Tertiary. Our findings are contrary to the opinion that continental interiors are insensitive to compression at plate margins, and help to explain the mechanisms causing intraplate orogenesis.