Did mid‐Ediacaran regional sea‐level drawdown trigger extensive allochthonous salt breakout and the incision of kilometre‐deep palaeocanyons, Flinders Ranges, South Australia?

Abstract

The Ediacaran Period is of interest for the emergence of multicellular life, one or more glaciations, and the occurrence of the largest δ13C excursion in Earth history (the Shuram). The Ediacaran stratigraphic succession in the Flinders Ranges of South Australia is distinctive also for well‐exposed outcrop examples of palaeocanyons and salt diapirs. We present data placing a level of salt‐sheet breakout during deposition of the Wonoka Formation, within the time span of the Shuram, and at a datum indistinguishable from the canyon incision level. We hypothesize that canyon incision and salt breakout were triggered by subaerial erosion and non‐deposition associated with sea‐level drawdown in a temporarily isolated embayment. This mechanism provides support for the idea that the palaeocanyons were fluvially incised, and imposes a new constraint on the palaeoenvironmental setting of Australia at the time of the Shuram and the Ediacara fauna.