Zebra rock and other Ediacaran paleosols from Western Australia

Abstract

Zebra rock is an ornamental stone from the early Ediacaran, Ranford Formation, around and in Lake Argyle, south of Kununurra, Western Australia. It has been regarded as a marine clay, liquid crystal, groundwater alteration, unconformity paleosol or product of acid sulfate weathering. This study supports the latter hypothesis and finds modern analogues for its distinctive red banding in mottling of gleyed soils. Other acid sulfate paleosols of desert playas (Gypsids) are also are found in the Ranford Formation, as well as calcareous desert paleosols (Calcids). The megafossil Palaeopaschnicnus also found in associated grey shales may have been a chambered protozoan, but Yangtziramulus in calcic paleosols is most like a microbial earth lichen. Soil climofunctions are evidence of an arid, cool temperate climate during the early Ediacaran.

KEY POINTS

1. Ornamental stones known as ‘zebra rock’ are interpreted as Ediacaran gleyed soils.

2. Gypsum desert-rose beds are interpreted as Ediacaran acid sulfate soils (Gypsids).

3. Calcareous nodular loess beds are interpreted as Ediacaran desert soils (Gypsids).

Keywords:

• Ranford Formation
• Ediacaran
• paleosols
• Yangtziramulus
• Palaeopascichnus

Acknowledgements

Bruce Runnegar, Shuhai Xiao, Natalia Bykova and Dima Grazhdankin offered useful discussion. Brian and Jo Fennell generously provided illustrations and slabs of Snappy Gum Ridge zebra rock, and access to their quarry on Donkey Creek. Ruth Duncan generously offered a tour of the Duncan Road quarry, and permission to collect there. I am grateful for helpful reviews from Paul Carr and an anonymous reviewer.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

Supplementary data that support the findings of this study are openly available from the University of Oregon at https://doi.org/10.7910/DVN/OXAFZI