The Amadeus Basin, central Australia

Abstract

The Amadeus Basin of central Australia has a depositional history spanning the Neoproterozoic to the Devonian/Carboniferous. It was initiated as part of the Neoproterozoic Centralian Superbasin, which formed in an intracratonic setting related to the break up of Rodinia. Sedimentation continued until the 580-540 Ma Petermann Orogeny, coinciding with the assembly of Gondwana, which resulted in the fragmentation of the superbasin into separate intracratonic basins. The Petermann Orogeny was focused in the Musgrave Province and the southern part of the Amadeus Basin, and involved significant N-directed shortening on large-scale structures that involved both the basement and the overlying Neoproterozoic sedimentary rocks. It significantly transformed the basin architecture, with the development of major basin features that controlled subsequent sedimentation. Deposition of Paleozoic successions was largely concentrated in sub-basins and troughs in the N of the basin, where up to 14 km is preserved. Minor events or uplifts punctuated this depositional history and account for local disconformities and absent sections. The 450-300 Ma Alice Springs Orogeny was a multi-phase, intracratonic event concentrated in the Arunta Region and the northern part of the Amadeus Basin. Like the earlier Petermann Orogeny, the Alice Springs Orogeny involved both basement and basin sedimentary rocks, but with overall S-directed movement. Synorogenic sedimentation accompanied Mid-Late Devonian uplift, with Late Devonian-Carboniferous basin inversion terminating sedimentation, and folding the youngest successions. The Amadeus Basin has known reserves of U, minor historic and recent Au production, and is prospective for base metals, especially Cu, and phosphate. The Ordovician succession supports commercial gas production, and the Neoproterozoic succession is considered prospective for oil and gas.