The Adelaide Superbasin (previously known as the Adelaide Geosyncline and Adelaide Rift Complex) is a major Neoproterozoic to middle Cambrian geological province in central and south-east South Australia, western New South Wales, and western Victoria. It consists of a thick pile of sedimentary rocks and minor volcanic rocks that were deposited on the eastern margin of the Australian continent during the time of breakup of the supercontinent Rodinia. The Adelaide Superbasin has been the subject of much research, as it contains geological evidence for the breakup of Rodinia; two Snowball Earth events (the Sturtian and Marinoan glaciations); the Neoproterozoic oxygenation event, the transition to mostly eukaryotic life; and the Ediacaran Fauna.

The Adelaide Superbasin has been previously called the Adelaide Geosyncline (Mawson & Sprigg (1987); Preiss (2000)) and the Adelaide Rift Complex (Veevers et al. (1997).

This geological province consists of a thick pile of sedimentary rocks and minor volcanic rocks that were deposited on the eastern margin of Australia during the time of breakup of the supercontinent Rodinia. A number of authors have noted the similarity in these sedimentary rocks with rocks found in western North America and have suggested that they were formerly adjacent to each other in Rodinia. This is one major correlation in the SWEAT (south-west USA against East Antarctica) reconstruction of Rodinia.

North–south it stretches over 850 km (530 mi) from the Peake and Denison Ranges in the central-north of South Australia down through the Flinders Ranges and Mount Lofty Ranges, narrowing at the Fleurieu Peninsula and extending onto Kangaroo Island. West–east it stretches about 700 km (430 mi) from the eastern margin of Lake Gairdner across to the Barrier Ranges of New South Wales. The true northern and eastern extent of the Adelaide Superbasin is not well known due to much of the basin being buried beneath younger basins, including the Murray Basin, and is the subject of current research.

It is thought that the Moyston Fault in Victoria marks the eastern boundary and the northern extension may continue underneath and potentially include the Warburton Basin; however, this remains speculative. Most of the outcropping rock today is within the two major mountain ranges of South Australia: the Flinders Ranges and the Mount Lofty Ranges.

Much like the partly coeval Centralian Superbasin it contains several named basins and sub-basins. The oldest and largest of these is the Adelaide Rift Complex, with the adjoining and relatively undeformed Stuart Shelf, Torrens Hinge Zone and Coombalarnie Platform making up the remaining Neoproterozoic provinces. The Stansbury Basin (including its sub-province the Kanmantoo Province/Trough) and Arrowie Basin (including its sub-province the Yalkalpo Sub-basin) are the two known Cambrian provinces within the Adelaide Superbasin.

Deposition in the Adelaide Superbasin began just prior to 830 Ma as Laurentia (and possibly an intervening continent, see Rodinia for alternative reconstructions) began to rift away from Australia during the breakup of the supercontinent Rodinia. Deposition continued through to the Delamerian Orogeny c. 514–490 Ma at which time deposition in the Adelaide Superbasin stopped and the rocks were folded and deformed. Initially, deposition occurred from gradual subsidence of peneplained cratonic lithosphere before developing into a rift basin.

After about 725 Ma, deposition continued in a mostly passive margin setting along the western edge of the Palaeo-Pacific Ocean, with renewed rifting during the Ediacaran to the east (present day) of the main depocentres until being terminated by the Delamerian Orogeny. The most abundant rock types indicate a transition from evaporitic depositional environments through to proximal marine, glacial and marine depositional environments. The thickest parts of the stratigraphy reach a total cumulative thickness of about 24,000 m.