Subduction geometry controls on dynamic topography: implications for the Jurassic Surat Basin

The Late Jurassic Springbok unconformity in the Surat Basin remains to date at odds with our understanding of basin-forming processes. A previously proposed cause for the unconformity is uplift related to the rifting of the Argo landmass from Western Australia, but the great distance between the Surat Basin and the Argo rift-zone argues against this interpretation. A more likely scenario is that the uplift was related to a west-dipping subduction zone along the east Australian margin. Numerous examples around the world link subduction processes, such as tears and detaching segments of the slab, to variations in surface topography. We used geodynamic forward modelling to generate uplift in the overriding plate of a subduction zone, as well as topographic changes that occur as subduction is disrupted by slab breakoff or tears. Our findings suggest that slab tearing can produce distribution and magnitude of uplift consistent with the Jurassic uplift in the Surat Basin, which potentially adds new insights into the tectonic evolution of eastern Australia.