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.

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.

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.
Ediacara Member: Getting up to 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.
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. It is also sometimes simply referred to as the Upper Rawnsley Quartzite Member.

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, whilst the second one yields an age of. Meanwhile, another single grain from the underlying Bonney Sandstone yielded an age of.
Due to these very few dates, a date of has been used as the Ediacara Member is known to correlate with the Zimnygory section in the Ustʹ Pinega Formation, Russia.

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. 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. 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.
One researcher, Gregory Retallack, has regarded the member as being that of a terrestrial environment based on iron oxide coatings found within it, 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. Despite this piece of evidence, alongside a growing collection of other studies done before and after, Retallack still supports a terrestrial environment for the Rawnsley Quartzite.

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, to the classic Ediacaran forms such as Dickinsonia and Arborea. 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" in literature.

Bilaterian

Genus	Species	Notes	Images
Ikaria	I. wariootia	Worm-like organism.
Kimberella	K. quadrata	Mollusc-like organism.
Uncus	U. dzaugisi	Worm-like organism.
~~Velocephalina~~	~~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	E. flindersi	Discoidal organism.

Porifera

Genus	Species	Notes	Images
Palaeophragmodictya	P. reticulata
Funisia	F. dorothea	Olgunid tubular organism.

Petalonamae

Genus	Species	Notes	Images
Arborea	A. arborea	Frondose organism.
Akrophyllas	A. longa	Frondose organism.
Charniodiscus	Charniodiscus sp.	Frondose organism.
Pteridinium	Pteridinium sp. P. simplex	Recumbent frondose organism

Proarticulata

Genus	Species	Notes	Images
Andiva	A. ivantsovi	Elongated motile organism, with glided reflection.
Archaeaspinus	A. fedonkini	Rounded motile organism, with glided reflection.
Dickinsonia	D. costata D. tenuis	Oval motile organism, with glided reflection.
Marywadea	M. ovata	Elongated motile organism, with glided reflection.
Ovatoscutum	O. concentricum	Rounded motile organism, with glided reflection. Previously described as a porpitid.
Praecambridium	P. sigillum	Rounded motile organism.
Spriggina	S. floundersi	Elongated motile organism, with glided reflection.
Yorgia	Y. waggoneri	Rounded motile organism, with glided reflection.

Trilobozoa

Genus	Species	Notes	Images
Albumares	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	R. enigmaticus	Triradial organism.
Tribrachidium	T. heraldicum T. gehlingi	Triradial organism.

''incertae sedis''

Genus	Species	Notes	Images
Aspidella	A. terranovica	Disoidal organism.
Attenborites	A. janae	Pelagic oval organism.
Aulozoon	A. soliorum	Sessile, tubular organism.
Conomedusites	C. lobatus	Tetraradila organism, probable cnidarian.
Coronacollina	C. acula	Triradial sponge-like organism, with four spicule-like structures.
Cyclomedusa	Cyclomedusa sp.	Discoidal organism.
Eoandromeda	E. octobrachiata	Eight-armed radial organism.
Eoporpita	E. medusa	Discoidal organism, probable cnidarian.
Mawsonites	M. spriggi	Discoidal organism.
Nilpenia	N. rossi	Branching, tubular and sediment-dwelling organism.
Obamus	O. coronatus	Torus-shaped organism.
Parvancorina	P. minchami	Anchor-shaped organism.
Phyllozoon	P. hanseni	Interpreted as either an erniettomorph or a feeding trace.
Plexus	P. ricei	Worm-like organism, affinities unknown.
Pseudorhizostomites	P. howchini
Quaestio	Q. simpsonorum	Asymmetrical, rounded organism.
Somatohelix	S. sinuosus	Tubular organism.
Palaeopascichnus	Palaeopascichnus sp.	Palaeopascichnid organism
Intrites	Intrites sp.	Palaeopascichnid organism.

Flora

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

Ichnogenera

Genus	Species	Notes	Images
Helminthoidichnites	Helminthoidichnites sp.	Burrows.
Kimberichnus	K. terruzi	Feeding traces of Kimberella.

Undescribed

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