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Rawnsley Quartzite

The Rawnsley Quartzite is an Ediacaran geologic formation in South Australia. It is most well known for its preservation of organisms of the Ediacaran Biota.

Rawnsley Quartzite
Stratigraphic range: Late Ediacaran 555 Ma [1]
Exposed rocks of the Rawnsley Quartzite
TypeFormation
Unit ofPound Subgroup
Sub-unitsSee: Members
UnderliesUratanna Formation
OverliesBonney Sandstone
Area20,000 km2 (7,700 sq mi)[2]
Location
RegionSouth Australia
CountryAustralia

Geology

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Contrary to what the name suggests, the Rawnsley Quartzite is dominated by sandstone rocks. The formation is found entirely within the Nilpena Ediacara National Park, in the Flinders Ranges of Southern Australia.[3]

Members

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The Rawnsley Quartzite is composed of two formal members, and one currently informal member, which are as follows, in ascending stratigraphic order (lowest to highest):

  • Chace Quartzite Member: This member is primarily composed of white, fine to coarse-grained sandstone, which is petee-bedded and feldspathic.[3]
  • Ediacara Member: Getting up to 300 m (980 ft) thick, member is composed of various sandstones and quartzites. At the base of the member, there are predominately flat-laminated to rippled sandstone. This sandstone is khaki colored, weathers to a red color when exposed, and is fine to coarse-grained. Within these layers there can also be found white to brown feldspathic sandstone, which is medium to coarse-grained. In the middle of the member can be found gray-white, fine to coarse-grained sandstone, which is thin to medium-bedded and features wave ripples. Further towards the top of the member there are white, medium to coarse-grained arenite, which contains quartz and is feldspathic. It is also the fossil bearing member of the formation.[3]
  • Nilpena Sandstone/Upper Rawnsley Quartzite Member: This member is the informal one of the three, being at the very top of the formation, and contains very few fossils, mostly discoidal in appearance. It is primarily composed of fine-grained sandstones.[4] It is also sometimes simply referred to as the Upper Rawnsley Quartzite Member.[2]

Dating

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The dating of the formation, and primarily the Ediacara Member, has been hindered due to the coarse-grained siliciclastic sedimentology of it. Despite this, there have been two grains dated through U-Pb dating that get close to a probable depositional age of the aforementioned member. The first grain yielded an age of 561.9±15.1 Ma, whilst the second one yields an age of 596±10 Ma. Meanwhile, another single grain from the underlying Bonney Sandstone yielded an age of 566±24 Ma.[1]

Due to these very few dates, a date of 555±0 Ma has been used as the Ediacara Member is known to correlate with the Zimnygory section in the Ustʹ Pinega Formation, Russia.[1]

Paleoenvironment

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The environment at the time of the Ediacara Member's deposition was that of a shallow marine one, ranging from an estuarine, shoreface, and coastal environments.[2] Previous studies had a slightly wider range, with the environment going from the fair-weather wave base to a sub-storm wave base, as well as a delta-front, which ranged from a near to below the wave base.[3] The shallow marine environment was also inferred from the relatively thick matgrounds commonly found in most fossil beds of the member, which would have also helped to support the community of organisms within the general area.[3]

One researcher, Gregory Retallack, has regarded the member as being that of a terrestrial environment based on iron oxide coatings found within it,[5] although further studies done after have discounted these findings suggesting a terrestrial deposition for the member, as the compounds had been precipitated from groundwater beneath the member in the last ~2 million years.[6] Despite this piece of evidence, alongside a growing collection of other studies done before and after,[7] Retallack still supports a terrestrial environment for the Rawnsley Quartzite.[8]

Paleobiota

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The beds at Nilpena Ediacara National Park contains a diverse, and complex system of Ediacaran organisms, from bilateral forms such as Parvancorina and Kimberella,[9] to the classic Ediacaran forms such as Dickinsonia and Arborea.[9] Due to its notable shallow environment, there is also a wide collection of algae forms, such as Flabellophyton and Longifuniculum, which are commonly referred to as "Bundles of Filaments" (BOF) in literature.[10][9]

Color key
Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon
 Notes
Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Bilaterian

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Genus Species Locality Notes Images
Ikaria[9]
  • I. wariootia
 1T-F Surface Worm-like organism.
Kimberella[11][4][9]
  • K. quadrata
 NECP Bed-1 Mollusc-like organism.
Uncus[9]
  • U. dzaugisi
 1T-F Surface Worm-like organism.
Velocephalina[12]
  • V. greenwoodensis
 NECP Bed-1 Surface Mollusc-like organism. Due to being named exclusively in a PhD thesis, it is considered a nomen ineditum, meaning it was not properly published.

Cnidarian

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Genus Species Locality Notes Images
Ediacaria[13]
  • E. flindersi
 Discoidal organism.

Porifera

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Genus Species Locality Notes Images
Palaeophragmodictya[10]
  • P. reticulata
 TC-MM3 Surface
Funisia[9]
  • F. dorothea
 1T-F, TC-MM3, and TR-ARB Surfaces Olgunid tubular organism.

Petalonamae

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Genus Species Locality Notes Images
Arborea[11][9]
  • A. arborea
 NECP Bed-1 Surface Frondose organism.
Akrophyllas[14]
  • A. longa
 Frondose organism.
Charniodiscus[11]
  • Charniodiscus sp.
 NECP Bed-1 Surface Frondose organism.
Pteridinium[4]
  • Pteridinium sp.
  • P. simplex
 Recumbent frondose organism

Proarticulata

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Genus Species Locality Notes Images
Andiva[10][9]
  • A. ivantsovi
 1T-F and TR-ARB Surfaces Elongated motile organism, with glided reflection.
Archaeaspinus[15]
  • A. fedonkini
 Rounded motile organism, with glided reflection.
Dickinsonia[11][4][10][9]
  • D. costata
  • D. tenuis
 NECP Bed-1, 1T-F, TC-MM3, and TR-ARB Surfaces Oval motile organism, with glided reflection.
Marywadea[16]
  • M. ovata
 Elongated motile organism, with glided reflection.
Ovatoscutum[13]
  • O. concentricum
 Rounded motile organism, with glided reflection. Previously described as a porpitid.
Praecambridium[17][11]
  • P. sigillum
 NECP Bed-1 Surface Rounded motile organism.
Spriggina[11][4][10][9]
  • S. floundersi
 NECP Bed-1 and 1T-F Surfaces Elongated motile organism, with glided reflection.
Yorgia[11][10]
  • Y. waggoneri
 NECP Bed-1 and TC-MM3 Surfaces Rounded motile organism, with glided reflection.

Trilobozoa

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Genus Species Locality Notes Images
Albumares (?)[18]
  • Albumares sp. (?)
 Triradial organism. No proper description or image has been published of its record here, as such it remains uncertain if Albumares can also be found here.
Rugoconites[10][11][9]
  • R. enigmaticus
 NECP Bed-1, 1T-F, and TC-MM3 Surfaces Triradial organism.
Tribrachidium[11][4][9]
  • T. heraldicum
  • T. gehlingi
 NECP Bed-1 and 1T-F Surfaces Triradial organism.

incertae sedis

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Genus Species Locality Notes Images
Aspidella[10][9]
  • A. terranovica
 1T-F and TC-MM3 Surface Disoidal organism.
Attenborites[19][10][9]
  • A. janae
 1T-F and TR-ARB Surfaces Pelagic oval organism.
Aulozoon[10][20][9]
  • A. soliorum
 1T-F, TC-MM3, and TR-ARB Surfaces Sessile, tubular organism.
Conomedusites[10]
  • C. lobatus
 TC-MM3 Surface Tetraradial organism, probable cnidarian.
Coronacollina[10][9]
  • C. acula
 1T-F and TR-ARB Surfaces Triradial sponge-like organism, with four spicule-like structures.
Cyclomedusa[21]
  • Cyclomedusa sp.
 Discoidal organism.
Eoandromeda[4]
  • E. octobrachiata
 Eight-armed radial organism.
Eoporpita[9]
  • E. medusa
 1T-F Surface Discoidal organism, probable cnidarian.
Harlaniella (?)[22]
  • Harlaniella (?) sp.
 Ribbon-like organism.
Mawsonites[10][9]
  • M. spriggi
 1T-F Surface Discoidal organism.
Nilpenia[23]
  • N. rossi
 Branching, tubular and sediment-dwelling organism.
Obamus[24][10][9]
  • O. coronatus
 1T-F and TB-ARB Surfaces Torus-shaped organism.
Parvancorina[11][4][10][9]
  • P. minchami
 NECP Bed-1, 1T-F, TC-MM3, and TB-ARB Surfaces Anchor-shaped organism.
Phyllozoon[4]
  • P. hanseni
 Interpreted as either an erniettomorph or a feeding trace.
Plexus[25][10]
  • P. ricei
 TB-ARB Surface Worm-like organism, affinities unknown.
Pseudorhizostomites[11][10]
  • P. howchini
 NECP Bed-1 Surface
Quaestio[9]
  • Q. simpsonorum
 1T-F Surface Asymmetrical, rounded organism.
Somatohelix[10]
  • S. sinuosus
 Tubular organism.
Palaeopascichnus[10][9]
  • Palaeopascichnus sp.
 1T-F and TB-ARB Surfaces Palaeopascichnid organism
Intrites[10]
  • Intrites sp.
 TC-MM3 and TR-ARB Surfaces Palaeopascichnid organism.

Flora

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Genus Species Locality Notes Images
Flabellophyton[10]
  • F. stupendum
  • F. typicum
 Filamentous macroalgae.
Liulingitaenia[10]
  • L. irregularis
 Filamentous macroalgae.
Longifuniculum[10]
  • L. dissolutum
 Whip-like macroalgae.

Ichnogenera

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Genus Species Locality Notes Images
Helminthoidichnites[4][10]
  • Helminthoidichnites sp.
 Burrows.
Epibaion[11]
  • E. costatus
NECP Bed-1 Surface Feeding traces of Dickinonsia.
Kimberichnus[26][11]
  • K. terruzi
 NECP Bed-1 Surface Feeding traces of Kimberella.

Undescribed

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Genus Species Locality Notes Images
Form 1[11]
  • ???
 NECP Bed-1 Surface Bilterial organism, bears similarities with Kimberella, although features a prominent "head" region at the front, and a "flange" at the rear.
Form 2[11]
  • ???
 NECP Bed-1 Surface Rounded organism, with a notable "head" shield.

See also

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References

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  1. 1 2 3 Reid, L. M.; Payne, J. L.; Tucker, N. M.; Jago, J. B. (17 February 2025). "Detrital zircon geochronology and sedimentary provenance of the fossiliferous Ediacara Member, South Australia". Australian Journal of Earth Sciences. 72 (2): 169–181. doi:10.1080/08120099.2025.2485976.
  2. 1 2 3 McMahon, William J.; Liu, Alexander G.; Tindal, Benjamin H.; Kleinhans, Maarten G. (30 November 2020). "Ediacaran life close to land: Coastal and shoreface habitats of the Ediacaran macrobiota, the Central Flinders Ranges, South Australia". Journal of Sedimentary Research. 90 (11): 1463–1499. doi:10.2110/jsr.2020.029.
  3. 1 2 3 4 5 Tarhan, Lidya G.; Droser, Mary L.; Gehling, James G.; Dzaugis, Matthew P. (2017). "Microbial Mat Sandwiches and Other Anactualistic Sedimentary Features of the Ediacara Member (rawnsley Quartzite, South Australia): Implications for Interpretation of the Ediacaran Sedimentary Record". PALAIOS. 32 (3): 181–194. ISSN 0883-1351.
  4. 1 2 3 4 5 6 7 8 9 10 Gehling, J. G.; García-Bellido, D. C.; Droser, M. L.; Tarhan, M. L.; Runnegar, B. (30 December 2019). "La transición ediacárico-cámbrica: facies sedimentarias versus extinción". Estudios Geológicos. 75 (2): e099. doi:10.3989/egeol.43601.554.
  5. ↑ Retallack, Gregory J. (January 2013). "Ediacaran life on land". Nature. 493 (7430): 89–92. doi:10.1038/nature11777.
  6. ↑ Tarhan, L. G.; Planavsky, N. J.; Wang, X.; Bellefroid, E. J.; Droser, M. L.; Gehling, J. G. (January 2018). "The late‐stage "ferruginization" of the Ediacara Member (Rawnsley Quartzite, South Australia): Insights from uranium isotopes". Geobiology. 16 (1): 35–48. doi:10.1111/gbi.12262.
  7. ↑ Weyland, W. C.; Droser, M. L. (2025-11-17). "Reply to comment by Retallack (2025) on ' The Ediacaran aquarium: insights from the Nilpena Ediacara National Park 1T-F marine ecosystem (Ediacara member, Rawnsley Quartzite) '". Australian Journal of Earth Sciences. 72 (8): 1161–1163. doi:10.1080/08120099.2025.2590158. ISSN 0812-0099.
  8. ↑ Retallack, G. J. (2025-11-17). "Comment on ' The Ediacaran aquarium: insights from the Nilpena Ediacara National Park 1T-F marine ecosystem (Ediacara member, Rawnsley Quartzite) ' by Weyland and Droser (2025)". Australian Journal of Earth Sciences. 72 (8): 1159–1160. doi:10.1080/08120099.2025.2590157. ISSN 0812-0099.
  9. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 Weyland, W. C.; Droser, M. L. (17 February 2025). "The Ediacaran Aquarium: insights from the Nilpena Ediacara National Park 1T-F Marine Ecosystem (Ediacara Member, Rawnsley Quartzite)". Australian Journal of Earth Sciences. 72 (2): 151–168. doi:10.1080/08120099.2025.2462660.
  10. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Xiao, Shuhai; Gehling, James G.; Evans, Scott D.; Hughes, Ian V.; Droser, Mary L. (November 2020). "Probable benthic macroalgae from the Ediacara Member, South Australia". Precambrian Research. 350 105903. doi:10.1016/j.precamres.2020.105903.
  11. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Coutts, Felicity J.; Gehling, James G.; García-Bellido, Diego C. (October 2016). "How diverse were early animal communities? An example from Ediacara Conservation Park, Flinders Ranges, South Australia". Alcheringa: An Australasian Journal of Palaeontology. 40 (4): 407–421. doi:10.1080/03115518.2016.1206326.
  12. ↑ Coutts, Felicity J. (January 2019). Palaeoecology of Ediacaran communities from the Flinders Ranges of South Australia (PhD thesis). University of Adelaide. doi:10.13140/RG.2.2.27075.96802.
  13. 1 2 Glaessner, M.F.; Wade, M. (1966). "The late Precambrian fossils from Ediacara, South Australia" (PDF). Palaeontology. 9 (4): 599. Archived from the original on September 27, 2007.
  14. ↑ Grimes, Kelsey F.; Narbonne, Guy M.; Gehling, James G.; Trusler, Peter W.; Dececchi, T. Alexander (March 2024). "Elongate Ediacaran fronds from the Flinders Ranges, South Australia". Journal of Paleontology. 98 (2): 249–265. doi:10.1017/jpa.2023.45.
  15. ↑ Mikhail A. Fodonkin, James G. Gehling, Kathleen Grey, Guy M. Narbonne, Patricia Vickers-Rich (2007). The Rise of Animals, Evolution and Diversification of the Kingdom Animalia. Johns Hopkins University Press, Baltimore. p. 261. ISBN 978-0-8018-8679-9.{{cite book}}: CS1 maint: multiple names: authors list (link)
  16. ↑ Glaessner, Martin F. (1976). "A new genus of late Precambrian polychaete worms from South Australia" (PDF). Transactions of the Royal Society of South Australia. 100 (3): 169–170. Archived from the original (PDF) on 2007-09-29.
  17. ↑ Glaessner, Martin F.; Wade, Mary (January 1971). "PRAECAMBRIDIUM ‐ A PRIMITIVE ARTHROPOD". Lethaia. 4 (1): 71–77. doi:10.1111/j.1502-3931.1971.tb01280.x.
  18. ↑ Gehling, J.G.; Droser M.L. (2009). "Textured organic surfaces associated with the Ediacara biota in South Australia". Earth-Science Reviews. 96 (3): 196–206. Bibcode:2009ESRv...96..196G. doi:10.1016/j.earscirev.2009.03.002.
  19. ↑ Droser, M. L.; Evans, S. D.; Dzaugis, P. W.; Hughes, E. B.; Gehling, J. G. (17 August 2020). "Attenborites janeae: a new enigmatic organism from the Ediacara Member (Rawnsley Quartzite), South Australia". Australian Journal of Earth Sciences. 67 (6): 915–921. doi:10.1080/08120099.2018.1495668.
  20. ↑ Surprenant, Rachel L.; Gehling, James G.; Hughes, Emmy B.; Droser, Mary L. (October 2023). "Biostratinomy of the enigmatic tubular organism Aulozoon soliorum, the Rawnsley Quartzite, South Australia". Gondwana Research. 122: 138–162. doi:10.1016/j.gr.2023.06.010.
  21. ↑
    • Sprigg, R. C. (1947): "Early Cambrian jellyfishes (?) from the Flinders Range, South Australia", Transactions of the Royal Society of South Australia. 71.2, p. 220
  22. ↑ Ivantsov, A. Yu. (November 2013). "New data on Late Vendian problematic fossils from the genus Harlaniella". Stratigraphy and Geological Correlation. 21 (6): 592–600. Bibcode:2013SGC....21..592I. doi:10.1134/S0869593813060051. eISSN 1555-6263. ISSN 0869-5938. S2CID 140579599.
  23. ↑ Droser, Mary L.; Gehling, James G.; Dzaugis, Mary E.; Kennedy, Martin J.; Rice, Dennis; Allen, Michael F. (January 2014). "A new Ediacaran fossil with a novel sediment displacive life habit". Journal of Paleontology. 88 (1): 145–151. doi:10.1666/12-158.
  24. ↑ Dzaugis, P. W.; Evans, S. D.; Droser, M. L.; Gehling, J. G.; Hughes, I. V. (17 August 2020). "Stuck in the mat: Obamus coronatus , a new benthic organism from the Ediacara Member, Rawnsley Quartzite, South Australia". Australian Journal of Earth Sciences. 67 (6): 897–903. doi:10.1080/08120099.2018.1479306.
  25. ↑ Joel, Lucas V.; Droser, Mary L.; Gehling, James G. (2014). "A New Enigmatic, Tubular Organism from the Ediacara Member, Rawnsley Quartzite, South Australia". Journal of Paleontology. 88 (2): 253–262. ISSN 0022-3360.
  26. ↑ Gehling, James G.; Runnegar, Bruce N.; Droser, Mary L. (2014). "Scratch Traces of Large Ediacara Bilaterian Animals". Journal of Paleontology. 88 (2): 284–298. ISSN 0022-3360.
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