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Candelária Formation
Candelária Formation
Stratigraphic range: Late Carnian (Tuvalian); ~231.4–222 Ma PreꞒ Ꞓ O S D C P T J K Pg N
	Outcrop map of the Candelária Formation
Type	Geological formation
Unit of	Santa Maria Group
Sub-units	Hyperodapedon & Riograndia Assemblage Zones
Underlies	Caturrita Formation
Overlies	Santa Maria Formation
Lithology
Primary	Mudstone
Other	Sandstone
Location
Coordinates	29°36′S 53°30′W / 29.6°S 53.5°W
Approximate paleocoordinates	42°24′S 14°42′W / 42.4°S 14.7°W
Region	Rio Grande do Sul
Country	Brazil
Extent	Paraná Basin
Type section
Named for	Candelária
	Candelária Formation, Paraná Basin (Brazil)

The Candelária Formation, in other literature also referred to as Candelária Sequence,^[1]^[2]^[3] is a sedimentary formation of the Santa Maria Group (also called Santa Maria Supersequence) in the Paraná Basin in Rio Grande do Sul, southeastern Brazil.^[4] The formation dates to the Carnian of the Late Triassic, locally referred to as Tuvalian, from 231.4 to approximately 222 Ma.

The Candelária Formation is composed of mudstones and sandstones deposited in a lacustrine to deltaic (distal floodplain) environment. It overlies the Santa Maria Formation and is partly overlain by and partly laterally equivalent to the Caturrita Formation. The formation comprises two Assemblage zones; the older Hyperodapedon and the younger Riograndia Assemblage Zones. Several cynodonts and other therapsids as well as early dinosaurs were found in the formation in the vicinity of Agudo.

Description

The Candelária Formation or Sequence corresponds to a third-order sequence placed in the Santa Maria Supersequence. The basal portion of the formation consists of a coarsening-upward succession that begins with red mudstones, interbedded with small-scale trough cross-bedded sandstone lenses. Rhythmites and sigmoidal massive to climbing cross-laminated sandstone bodies are also present. This facies association is interpreted as a lacustrine to deltaic (distal floodplain)^[5] depositional environment in a humid climate. The formation contains the Hyperodapedon and Riograndia Assemblage Zones.^[6]^[7]

The red beds are divided into a non-fossiliferous portion at the base, and an upper fossiliferous unit. Coprolites and putative rhizoliths are present. A light-colored cross-bedded sandstone also occurs at the top of the formation and represents a river channel. It is delimited by an erosive contact with the underlying red beds.^[5]

The Candelária Formation is considered a local equivalent of the Caturrita Formation,^[8] which it partly underlies. It overlies the Santa Maria Formation.^[9] The formation is correlated with the Ischigualasto Formation of the Ischigualasto-Villa Unión Basin in northwestern Argentina.^[2]

Basin history

The megaregional Paraná Basin, covering an approximate area of 1,500,000 square kilometres (580,000 sq mi) in southeastern South America, was in the late Paleozoic and early Mesozoic part of Gondwana, the southern latitude area of Pangea. Before the opening of the South Atlantic, a rifting phase that started in the Jurassic, the basin was connected to the basins of present-day southern Africa. The Candelária Formation forms part of the Gondwana II Supersequence representing the onset of continental deposition in the Paraná Basin. The Triassic paleofauna of the Paraná Basin is correlated with the African faunas of the Omingonde Formation of the Waterberg Basin in Namibia, the Molteno Formation of the Karoo Basin in South Africa and the Fremouw Formation of present-day Antarctica.^[10]

Fossil content

The formation has provided fossils of therapsids characteristic of the Late Triassic, as well as early dinosaurs.^[4]

Group	Fossils	Assemblage zone	Image	Notes
Dinosaurs	Erythrovenator jacuiensis			^[11]
	Macrocollum itaquii			^[12]
	Dinosauria indet.			^[13]
	Archosauromorpha indet.			^[14]
Therapsids	Brasilitherium riograndensis	Riograndia	Brasilitherium riograndensis	^[2]
	Brasilodon quadrangularis	Riograndia	Brasilitherium riograndensis	^[2]
	Botucaraitherium belarminoi	Riograndia		^[15]
	Irajatherium hernandezi	Riograndia		^[2]
	Prozostrodon brasiliensis	Hyperodapedon		^[2]^[16]
	Siriusgnathus niemeyerorum			^[14]
	Probainognathia indet.			^[14]
Rhynchosaurs	Hyperodapedon sp.	Hyperodapedon		^[7]^[16]
Rhynchocephalians	Lanceirosphenodon ferigoloi	Riograndia		^[17]

References

^ Müller et al., 2017, p.543
^ ^a ^b ^c ^d ^e ^f Botha-Brink, 2018, p.7
^ Martinelli et al., 2017, p.528
^ ^a ^b Candelária Formation at Fossilworks.org
^ ^a ^b Pretto et al., 2015, p.2
^ Soares et al., 2014, p.1675
^ ^a ^b Pacheco et al., 2017, p.2
^ Da Rosa & Faccini, 2005, p.21
^ Da Rosa & Faccini, 2005, p.18
^ Milani et al., 2007
^ Rodrigo T. Müller (2020). "A new theropod dinosaur from a peculiar Late Triassic assemblage of southern Brazil". Journal of South American Earth Sciences. in press: Article 103026. doi:10.1016/j.jsames.2020.103026.
^ Müller, Rodrigo Temp; Langer, Max Cardoso; Dias-da-Silva, Sérgio (November 2018). "An exceptionally preserved association of complete dinosaur skeletons reveals the oldest long-necked sauropodomorphs". Biology Letters. 14 (11): 20180633. doi:10.1098/rsbl.2018.0633. ISSN 1744-9561. PMC 6283919. PMID 30463923.
^ Müller et al., 2018, p.545
^ ^a ^b ^c Niemeyer, Agudo at Fossilworks.org
^ Soares et al., 2014, p.1677
^ ^a ^b Marchezan at Fossilworks.org
^ Romo de Vivar et al., 2020