Cascada Grande Donwstream waterfall "Level 4": Early/Lower Pliocene, Argentina

List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
Amphibia - Temnospondyli - Ceratophrynidae
Ceratophrys sp. Wied 1824
Mammalia - Panameriungulata - Macraucheniidae
Macraucheniidae indet. Ameghino 1889
Mammalia - Rodentia - Octodontidae
Pithanotomys sp. Ameghino 1887
    = Pithanotomys columnaris Ameghino 1887
Romano et al. 2023
Mammalia - Rodentia - Ctenomyidae
Actenomys sp. Burmeister 1888
Mammalia - Rodentia - Chinchillidae
Lagostomus incisus Ameghino 1888
recombined as Lagostomus (Lagostomopsis) incisus
Mammalia - Rodentia - Caviidae
Caviidae indet. Gray 1821
Mammalia - Notoungulata
Paedotherium sp. Burmeister 1888
see common names

Geography
Country:Argentina State/province:Buenos Aires
Coordinates: 38.6° South, 60.6° West (view map)
Paleocoordinates:38.7° South, 59.5° West
Basis of coordinate:stated in text
Geographic resolution:small collection
Time
Period:Neogene Epoch:Pliocene
Stage:Zanclean 10 m.y. bin:Cenozoic 6
Key time interval:Early/Lower Pliocene
Age range of interval:5.33300 - 3.60000 m.y. ago
Age estimate:4.33 ± 0.06 Ma (Ar/Ar)
Stratigraphy
Formation:Irene
Local section:Cascada Grande Local bed:4
Local order:bottom to top
Stratigraphy comments: 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.
Lithology and environment
Primary lithology:paleosol/pedogenic,nodular siltstone
Includes fossils?Y
Lithology description: 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).
Environment:terrestrial indet.
Taphonomy
Modes of preservation:body
Size of fossils:macrofossils
Collection methods and comments
Collection methods:field collection
Reason for describing collection:taxonomic analysis
Museum repositories:MLP
Metadata
Also known as:Cifuentes or de Aldaya, 2.85 km downstream from RN3
Database number:191770
Authorizer:E. Vlachos, J. Carrillo Enterer:E. Vlachos, K. Pino
Modifier:K. Pino
Created:2018-02-14 08:00:32 Last modified:2023-08-15 09:48:30
Access level:the public Released:2018-02-14 08:00:32
Creative Commons license:CC BY
Reference information

Primary reference:
64699. 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]

Secondary references:

85650 C. O. Romano, R. Bonini, S. Hemming, M. Cenizo, U. F. J. Pardiñas and F. J. Prevosti. 2023. Advances in the understanding of Neogene mammalian fauna in the Pampean region (central Argentina) through revising “biozone” hypotheses based on new dates and biochronological analyses. Ameghiniana 60(5):465-491 [J. Carrillo/K. Pino]