PBDB Collection

Cascada Grande Donwstream waterfall "Level 2" (Pliocene of Argentina)

Also known as Cifuentes or de Aldaya, 2.85 km downstream from RN3

Where: Buenos Aires, Argentina (38.6° S, 60.6° W: paleocoordinates 38.7° S, 59.5° W)

• coordinate stated in text

• small collection-level geographic resolution

When: Irene Formation, Early/Lower Pliocene (5.3 - 3.6 Ma)

• Prevosti et al. 2021: On analysis, one aliquot of a sample from QSLo (lower Quequén Salado, Paso del Halcón) presented extensive evidence of excess argon in the first half of the spectrum, but the final steps representing about 50% of released 39Ar yielded an age of 5.17 ± 0.08 Ma. A single aliquot of a sample from QSUp (upper Quequén Salado, Cascada Grande) gave an age of 4.33 ± 0.06 Ma. Our results close almost a century of argument concerning the relative antiquity of the “Irenean”( Kraglievich 1934, Goin et al. 1994, Pardiñas et al. 2017, Beilinson et al. 2017). The controversial lower fauna from the Quequén Salado River can now be shown to be of Zanclean age (5.17 Ma) and thus well within the Early Pliocene. Its upper fauna is also Early Pliocene (4.33 Ma), a point previously unclear.

Environment/lithology: terrestrial; brown, red, calcareous sandstone

• These are the most complex and diverse “Irenean” outcrops along the studied sector of the Quequén Salado River. The succession downstream of the waterfall can be seen in 5–7 m high cliffs on both sides of the river. The succession starts with a basal layer (level #1) of greenish brown massive carbonatic silt covered by a petrocalcic crust. This bed is only exposed downstream the first tufa barrier (Fig. 4) and its real expression can be asserted from the semi-hidden profiles covered with vegetation and tufa blocks in the left margin of the river (Fig. 3). There, just where the ancient tufa barrier collapsed, level #1 composed the whole 2 m high profile. The overlying sediments are reddish-brown sandstones with plenty of biogenic structures filled by carbonate and sectors with dissecation cracks (level #2). Level #3 has two well- differentiated sections; the basal portion includes a paleosoil, a level composed by large carbonate nodules and a clayey upper term with abundant veins of carbonate; the roof of the upper portion is a massive carbonate crust (Fig. 4). Level #4 is a distinctive layer by its erosive “honeycomb” profile filled with loessoid silts; diamicton deposits appear toward the upper portion of this level (Fig. 4).

Size class: macrofossils

Reposited in the MLP

Primary reference: U. F. J. Pardinas, F. J. Prevosti, D. Voglino and M. Cenizo. 2017. A controversial unit within the argentine neogene: the “Irenean” fauna. Ameghiniana 54(6):655-680 [E. Vlachos/E. Vlachos]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 191768: authorized by Evangelos Vlachos, entered by Evangelos Vlachos on 14.02.2018, edited by Kateryn Pino

Creative Commons license: CC BY (attribution)

Taxonomic list

Show authors, comments, and common names

Amphibia
Salientia - Ceratophrynidae	Ceratophrys sp. Ceratophrys sp. Wied 1824 South American horned frog
Aves
Gruiformes - Hermosiornithidae	"Hermosiornis sp." = Mesembriornis "Hermosiornis sp." = Mesembriornis Moreno 1889 bird
Mammalia
Notoungulata - Hegetotheriidae	Paedotherium bonaerense Paedotherium bonaerense Ameghino 1887 notoungulate
Rodentia - Caviidae	Caviidae indet. Caviidae indet. Gray 1821 caviomorph
Rodentia - Echimyidae	Eumysops sp. Eumysops sp. Ameghino spiny rat
Rodentia - Ctenomyidae	Actenomys sp. Actenomys sp. Burmeister 1888 caviomorph
Panameriungulata - Macraucheniidae	Macraucheniidae indet. Macraucheniidae indet. Ameghino 1889 placental
Cingulata - Dasypodidae	Ringueletia simpsoni Ringueletia simpsoni Bordas 1933 armadillo
Didelphimorphia - Didelphidae	Hyperdidelphys parvula Hyperdidelphys parvula Ameghino 1904 opossum