Rawnsley Quartzite

Rawnsley Quartzite
Stratigraphic range: Late Ediacaran 555  Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓ [1]
Exposed rocks of the Rawnsley Quartzite
Type	Formation
Unit of	Pound Subgroup
Sub-units	See: Members
Underlies	Uratanna Formation
Overlies	Bonney Sandstone
Area	20,000 km2 (7,700 sq mi) [2]
Location
Region	South Australia
Country	Australia

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.

Geology

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

The Rawnsley Quartzite is composed of two formal Members, and one currently informal Member, which are as follows, in ascending age:

The members are as follows, listed by ascending age:

• 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

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 know to correlate with the Zimnygory section in the Ustʹ Pinega Formation, Russia. ^[1]

Paleoenvironment

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

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

Genus	Species	Notes	Images
Ikaria [9]	I. wariootia	Worm-like organism.
Kimberella [11] [4] [9]	K. quadrata	Mollusc-like organism.
Uncus [9]	U. dzaugisi	Worm-like organism.
Velocephalina [12]	V. greenwoodensis	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

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

Porifera

Genus	Species	Notes	Images
Palaeophragmodictya [10]	P. reticulata
Funisia [9]	F. dorothea	Olgunid tubular organism.

Petalonamae

Genus	Species	Notes	Images
Arborea [11] [9]	A. arborea	Frondose organism.
Akrophyllas [14]	A. longa	Frondose organism.
Charniodiscus [11]	Charniodiscus sp.	Frondose organism.
Pteridinium [4]	Pteridinium sp. P. simplex	Recumbent frondose organism

Proarticulata

Genus	Species	Notes	Images
Andiva [10] [9]	A. ivantsovi	Elongated motile organism, with glided reflection.
Archaeaspinus [15]	A. fedonkini	Rounded motile organism, with glided reflection.
Dickinsonia [4] [10] [9]	D. costata D. tenuis	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	Rounded motile organism.
Spriggina [4] [10] [9]	S. floundersi	Elongated motile organism, with glided reflection.
Yorgia [11] [10]	Y. waggoneri	Rounded motile organism, with glided reflection.

Trilobozoa

Genus	Species	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	Triradial organism.
Tribrachidium [4] [9]	T. heraldicum T. gehlingi	Triradial organism.

incertae sedis

Genus	Species	Notes	Images
Aspidella [10] [9]	A. terranovica	Disoidal organism.
Attenborites [19] [10] [9]	A. janae	Pelagic oval organism.
Aulozoon [10] [20] [9]	A. soliorum	Sessile, tubular organism.
Conomedusites [10]	C. lobatus	Tetraradila organism, probable cnidarian.
Coronacollina [10] [9]	C. acula	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	Discoidal organism, probable cnidarian.
Mawsonites [10] [9]	M. spriggi	Discoidal organism.
Nilpenia [22]	N. rossi	Branching, tubular and sediment-dwelling organism.
Obamus [23] [10] [9]	O. coronatus	Torus-shaped organism.
Parvancorina [4] [10] [9]	P. minchami	Anchor-shaped organism.
Phyllozoon [4]	P. hanseni	Interpreted as either an erniettomorph or a feeding trace.
Plexus [24] [10]	P. ricei	Worm-like organism, affinities unknown.
Pseudorhizostomites [10]	P. howchini
Quaestio [9]	Q. simpsonorum	Asymmetrical, rounded organism.
Somatohelix [10]	S. sinuosus	Tubular organism.
Palaeopascichnus [10] [9]	Palaeopascichnus sp.	Palaeopascichnid organism
Intrites [10]	Intrites sp.	Palaeopascichnid organism.

Flora

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

Ichnogenera

Genus	Species	Notes	Images
Helminthoidichnites [4] [10]	Helminthoidichnites sp.	Burrows.
Kimberichnus [25]	K. terruzi	Feeding traces of Kimberella.

Undescribed

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

See also

• Ediacaran biota

References

1. 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. 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. 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. 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. 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. 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. 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. 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   9780801886799.
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.
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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. 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.
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