Adelaide Superbasin sees billion years of geological upheaval, leaving glaciers and first multicellular life

The confirmed extent of the Adelaide Superbasin, stretching more than 850 kilometres from the Peake and Denison ranges in central north South Australia south to Kangaroo Island. The Dalamerian orogeny saw folding of geological strata that created a huge mountain range. The eroded stumps of that range are the Mount Lofty Ranges as Adelaide's backdop and Flinders Ranges in the north.

The Adelaide Superbasin,covering much of what became South Australia, was a geological province that experienced some of the most significant events in the dynamics of Earth’s prehistory.

These events were from the Neoproterozioc era (one billion to 538 million years ago) leading into Cambrian era. The Neoproterozoic era include the Cryogenian period, when ice sheets may have reached the equator and formed a snowball Earth. This left evidence of glaciers that were a notable feature of South Australia’s ancient geological record.

The last phase of Neoproterozioc was the Ediacaran – a new name given to a geological period by the discovery by Reg Sprigg in 1946 in the Flinders Ranges of Ediacaran fauna –  the earliest fossils of complex multicellular life, including the oldest definitive animals.

The Adelaide Superbasin, a thick pile of sedimentary rocks and minor volcanicc rocks from the eastern margin of Australia, began to be formed 830 million years ago during the breakup of the supercontinent Rodinia. The similarity of Adelaide Basin sedimentary rocks with those rocks found in western North America was noted.

The Adelaide Superbasin had several basins and sub basins, the oldest and largest being the Adelaide Rift complex. Deposition – the breaking down of rocks and soil – continued in the Adelaide Superbasin until 514 million to 490 million years ago when an orogeny or mountain-building event occurred.

This event was called the Delamerian orogeny after Delamere, a small town on the Fleurieu Peninsula, south of Adelaide, where evidence was found of it happening. The Delamerian orogeny caused major folding, buckling and faulting of the geological strata. It created a huge mountain range. The eroded stumps of that mountain range were left as the Mount Lofty and the Flinders ranges.

With the folding and faulting of the Delamerian orogeny were several intrusions, including the granites at Victor Harbor, at the bottom of the Fleurieu Peninsula and at Palmer in the eastern south Mount Lofty Ranges. The ranges formed during the Delamerian orogeny continued to erode, with intra-plate subsidence. In the south Mount Lofty Ranges. This resulted in rifting that caused graben or valley structures to be formed, creating the long parallel faults that shaped the Adelaide plains.