Neoproterozoic rifting in the southern Georgina Basin, central Australia: Implications for reconstructing Australia in Rodinia

Abstract

[1] A system of northwest striking Neoproterozoic rift basins underlies Paleozoic strata in the southern Georgina Basin of central Australia. Normal faults bounding these rift basins were selectively reactivated during the mid-Paleozoic Alice Springs Orogeny and are now expressed as high-angle reverse faults that invert the preexisting rift basins. Exhumed and eroded rift basin remnants are present in the hanging wall of the Oomoolmilla, Lucy Creek, Tarlton, and Toomba reverse faults, and rift basins may be preserved in the subsurface beneath the Toko Syncline and Burke River Structural Belt. Rift basin fill indicates two periods of extension: a major rift-forming episode between approximately 700 and 650 Ma (coeval with Sturtian glacial deposits) and a second episode of extension at approximately 600 Ma (coeval with Marinoan glacial deposits). This northwest striking rift system in central Australia supports results from other regions, indicating that the Neoproterozoic continental margin of Australia consisted of northwest striking rift segments offset by northeast striking transform faults. Such a configuration is geometrically incompatible with a Laurentian continental margin consisting of northeast striking rift segments and conflicts with reconstructions such as SWEAT and AUSWUS that match Australia with western Laurentia in the Rodinia supercontinent.