The Cerro Azul Formation (Spanish: Formación Cerro Azul), also described as Epecuén Formation, is a geological formation of Late Miocene (Tortonian, or Huayquerian in the SALMA classification) age in the Colorado Basin of the Buenos Aires and La Pampa Provinces in northeastern Argentina.[1][2]

Cerro Azul Formation
Stratigraphic range: Tortonian (Huayquerian)
~10–5.7 Ma
Fossil burrow fills in the Cerro Azul Formation
TypeGeological formation
Underliesalluvium
OverliesArroyo Chasicó Formation or
Crystalline basement
Thickness54 m (177 ft) (outcrop)
180 m (590 ft) (subsurface)
Lithology
PrimarySiltstone, sandstone
OtherConglomerate
Location
Coordinates35°42′S 64°42′W / 35.7°S 64.7°W / -35.7; -64.7
Approximate paleocoordinates35°54′S 62°42′W / 35.9°S 62.7°W / -35.9; -62.7
RegionBuenos Aires & La Pampa Provinces
CountryArgentina
ExtentColorado Basin
Type section
Named forCerro Azul, Epecuén Lake
Named byLinares et al.
Year defined1980

Outcrop map of the Cerro Azul Formation

The fluvial and aeolian siltstones, sandstones and tuffs of the formation contain many mammals, such as Thylacosmilus and Macrauchenia, reptiles, amphibians and fossils of terror birds as well as Argentavis, the largest flying bird ever discovered.

Description edit

 
Sedimentary logs of the Cerro Azul Formation

The Cerro Azul Formation crops out in patches in the southwestern Buenos Aires Province and southeastern Pampa Province. The Epecuén Formation has been correlated to the Cerro Azul Formation in the early 2000s. The Cerro Azul and Epecuén Formations were named after the Cerro Azul ("Blue Hill") and Epecuén Lake where the formation crops out.[3] The formation overlies crystalline basement or the Arroyo Chasicó Formation.[4] The mammal assemblage of the Cerro Azul-Epecuén unit is the most diverse for the Huayquerian Late Miocene age, possibly ranging into the Pliocene.[5] The formation is considered contemporaneous with the Río Negro Formation of the Colorado Basin.[6][7]

The unit is characterized by a monotonous succession of loess containing moderately developed paleosols. In particular, the formation is considered as representing the interval between 10 and 5.7 Ma. The maximum exposed thickness in outcrop is 54 metres (177 ft), although the unit reaches about 180 metres (590 ft) in the subsurface.[8]

The Cerro Azul Formation deposits were described by Linares et al. in 1980.[3] They are discontinuous along the whole occupied area in the provinces of La Pampa and Buenos Aires. They are composed of silts, sandy silts and very thin silty sands, reddish and brown colored, with a homogeneous and compact general aspect, and frequent carbonate nodules and evidences of pedogenic processes. Visconti et al. (2010) interpreted them as eolian deposits characterized by loessic materials, with a high percentage of lithic fragments and volcaniclastic sediments.[9]

The sediments and their fauna belong to a sedimentary and faunal cycle, which followed the withdrawal (around 10 Ma) of a widespread marine transgression that extended from central Argentina, to western Uruguay and southern Paraguay and Brazil, the "Paraná Sea" or mar paranense in Spanish.[10]

Large cylindrical sediment-filled structures, 115 of which interpreted as mammal burrows occur within the loess-paleosol sequence of the formation.[11]

Fossil content edit

The following fossils have been recovered from the formation:[1]

Locations:

La Pampa
  • Barrancas Coloradas - Cerro Azul Formation - La Pampa
  • Caleufú - Cerro Azul Formation - La Pampa
  • Cerro El Chancho - Cerro Azul Formation - La Pampa
  • Cerro Patagua - Cerro Azul Formation - La Pampa
  • Estancia Don Mariano - Cerro Azul Formation - La Pampa
  • Estancia El Recado - Cerro Azul Formation - La Pampa
  • Estancia Ré - Cerro Azul Formation - La Pampa
  • El Guanaco - Cerro Azul Formation - La Pampa
  • Huayquerías de San Carlos - Cerro Azul Formation - La Pampa
  • Laguna Chillhué - Cerro Azul Formation - La Pampa
  • Laguna Guatraché - Cerro Azul Formation - La Pampa
  • Quehué - Cerro Azul Formation - La Pampa
  • Salinas Grandes de Hidalgo - Cerro Azul Formation - La Pampa
  • Telen - Cerro Azul Formation - La Pampa
Buenos Aires
  • Bajo Giuliani - Cerro Azul Formation - Buenos Aires
  • Barrancas de Sarmiento - Cerro Azul Formation - Buenos Aires
  • Eduardo Castex - Cerro Azul Formation - Buenos Aires
  • Estancia los Médanos - Cerro Azul Formation - Buenos Aires
  • Estancia Quiñi-Malal - Cerro Azul Formation - Buenos Aires
  • Grünbein Cantera Seminario - Cerro Azul Formation - Buenos Aires
  • Grünbein Cantera Seminario Level 2 - Cerro Azul Formation - Buenos Aires
  • Laguna Epecuén - Cerro Azul Formation - Buenos Aires
  • Laguna La Paraguaya - Cerro Azul Formation - Buenos Aires
  • Puesto Colorado - Cerro Azul Formation - Buenos Aires
  • Ruta 14 - Cerro Azul Formation - Buenos Aires
  • Arroyo Guaminí - Epecuén Formation - Buenos Aires
  • Carhué - Epecuén Formation - Buenos Aires
  • Laguna de los Paraguayos - Epecuén Formation - Buenos Aires
  • Robilote Field - SE of Epecuén lagoon & E of Laguna de Epecuén - Epecuén Formation - Buenos Aires
  • Salinas Grandes de Hidalgo - Epecuén Formation - Buenos Aires
Group Clade Taxa Location Images Notes
Mammals Carnivora Cyonasua brevirostris Salinas de Hidalgo [12]
C. prebrevirostris Salinas de Hidalgo [12]
Cyonasua sp. Telén [13]
Sparassodonta Borhyaenidium musteloides Salinas de Hidalgo [12]
Thylacosmilus atrox El Guanaco
Quehué
Salinas de Hidalgo
 
[12][14]
Borhyaenidae indet. Telén [13]
Rodents Abrocoma antiqua Estancia Ré [15]
Cardiatherium aff. orientalis Laguna Chillhué
Laguna Guatraché
[16]
Chasichimys bonaerense Cerro Patagua [17]
C. scagliai Laguna Chillhué [17]
Neocavia pampeana Estancia El Recado [18]
Lagostomus pretrichodactyla Salinas de Hidalgo [12]
Neophanomys pristinus Estancia Don Mariano
Quehué
[19]
Palaeoctodon aff. simplicidens Bajo Giuliani [20][21]
Pampamys emmonsae Laguna Chillhué
Bajo Giuliani
Estancia Ré
[21][22]
Phtoramys hidalguense Barrancas Coloradas
Salinas de Hidalgo
[21][23]
Proctenomys simpsoni El Guanaco
Barrancas Coloradas
[24]
Reigechimys octodontiformis Bajo Giuliani
Estancia Ré
[25]
R. plesiodon Laguna Chillhué [26]
R. simplex Bajo Giuliani [25]
Tetrastylus araucanus Salinas de Hidalgo [12]
Theridomysops parvulus Telén [13]
Xenodontomys ellipticus Grünbein Cantera Seminario
Barrancas de Sarmiento
[27]
Phtoramys cf. hidalguense Grünbein Cantera Seminario [27]
Cardiomys sp. Salinas de Hidalgo [12]
Chasichimys sp. Bajo Giuliani [17]
Dolicavia sp. Grünbein Cantera Seminario [27]
Lagostomus (Lagostomopsis) sp. Grünbein Cantera Seminario
Barrancas de Sarmiento
Estancia Ré
Salinas de Hidalgo
[12][15][27]
Neocavia sp. Grünbein Cantera Seminario [27]
Neophanomys sp. Estancia Ré [28]
Orthomyctera sp. Grünbein Cantera Seminario
Salinas de Hidalgo
[27][12]
Palaeocavia sp. Grünbein Cantera Seminario
Barrancas de Sarmiento
Estancia Ré
[12][15][27]
Phtoramys sp. Estancia Ré [15]
Protabrocoma sp. Telén [13]
Tetrastylus sp. Telén [13]
aff. Clyomys sp. Barrancas Coloradas [21]
Caviidae indet. Barrancas de Sarmiento [27]
Ctenomyidae indet. Telén [13]
Echimyidae indet. Telén [13]
Hydrochoeridae indet. Salinas de Hidalgo [14]
Octodontoidea indet. Estancia Ré [28]
Xenarthra Aspidocalyptus castroi Robilote Field
Salinas de Hidalgo
[12][29]
Coscinocercus brachyurus Robilote Field
Salinas de Hidalgo
[12][29]
C. marcalaini Robilote Field
Salinas de Hidalgo
[12][29]
Hoplophractus tapinocefalus Laguna de los Paraguayos
Salinas de Hidalgo
[12][30]
Plohophorus araucanus Salinas de Hidalgo [12]
Proscelidodon gracillimus Estancia Don Mariano
Huayquerías de San Carlos
Laguna Epecuén
Bajo Giuliani
Laguna Chillhué
Loventué
Salinas Grandes de Hidalgo
Quehué
Barrancas Coloradas
Estancia Ré
Arroyo Guaminí
Laguna de los Paraguayos
Carhué
[31][32]
[33][34]
Aspidocalyptus sp. Telén [13]
Coscinocercus sp. Telén [13]
Eosclerocalyptus sp. Laguna La Paraguaya
 
[35]
Eumysops sp. Laguna Chillhué [21]
Hoplophorus sp. Telén [13]
Hoplophractus sp. Telén [13]
Plesiomegatherium sp. Salinas de Hidalgo [12]
cf. Aspidocalyptus sp. Grünbein Cantera Relleno Sanitario Level 2 [27]
cf. Pseudoplohophorus sp. Grünbein Cantera Relleno Sanitario Level 2 [27]
Glyptodontidae indet. Laguna La Paraguaya
Salinas Grandes de Hidalgo
[35]
Mylodontidae indet. Telén [13]
Cingulata Chasicotatus ameghinoi Laguna Chillhué
Estancia Don Mariano
Cerro Patagua
Cerro El Chancho
Cerro de los Guanacos
Puesto Colorado
Estancia Quiñi-Malal
Bajo Giuliani
El Guanaco
Telen
El Recado
Laguna Guatraché
Loventué
Quehué
Barrancas Coloradas
Estancia Ré
Salinas de Hidalgo
[13][36]
[37][38]
Chasicotatus cf. peiranoi Grünbein Cantera Relleno Sanitario Level 2 [27]
Chorobates villosissimus Laguna Chillhué
Estancia Don Mariano
Grünbein Cantera Relleno Sanitario Level 2
Puesto Colorado
Ruta 14
Estancia Quiñi-Malal
El Guanaco
Telen
El Recado
Loventué
Quehué
Estancia Ré
Salinas de Hidalgo
[12][27][36]
[37][38]
Doellotatus chapadmalensis El Recado
Salinas de Hidalgo
[12][38]
D. inornatus Laguna Chillhué
Estancia Don Mariano
Grünbein Cantera Seminario
Puesto Colorado
Ruta 14
El Guanaco
El Recado
Laguna Guatraché
Loventué
Quehué
Barrancas Coloradas
Estancia Ré
Telén
Salinas de Hidalgo
[12][27]
[36][37]
[38][13]
D. cf. praecursor Grünbein Cantera Seminario [27]
Macrochorobates chapalmalensis El Guanaco
Barrancas Coloradas
[36]
M. scalabrinii Laguna Chillhué
Estancia Don Mariano
Telen
Loventué
Quehué
Salinas de Hidalgo
[12][36]
[37][13]
Macroeuphractus morenoi Grünbein Cantera Relleno Sanitario Level 2
Puesto Colorado
Laguna Chillhué
Telen
El Recado
Laguna Guatraché
Loventué
Quehué
Barrancas Coloradas
Estancia Ré
Salinas de Hidalgo
[12][27]
[36][37]
[38][13]
M. retusus Salinas de Hidalgo [12]
Proeuphractus limpidus Laguna Chillhué
Telén
[36][13]
Vetelia perforata Cerro Patagua
Cerro de los Guanacos
Telén
[36][37][13]
Zaedyus pichiy Laguna Chillhué
Telen
Quehué
 
[37]
Chasicotatus sp. El Recado [27][38]
Chorobates sp. Grünbein Cantera Seminario [27]
Doellotatus sp. Laguna La Paraguaya [38]
Macrochorobates sp. Grünbein Cantera Relleno Sanitario Level 2
El Recado
[27][38]
Paleuphractus sp. Salinas de Hidalgo [12]
Proeuphractus sp. Laguna Chillhué
Cerro Patagua
Telen
El Recado
Laguna Guatraché
Quehué
Salinas de Hidalgo
[12][36]
[37][38]
[13]
Didelphimorphia Hyperdidelphys pattersoni El Guanaco
Telén
[14][13]
Thylamys pinei Laguna Chillhué [21]
T. zetti Estancia Ré
Arroyo Guaminí
[15][33]
Thylatheridium dolgopolae El Guanaco
Quehué
Telén
[39][13]
T. hudsoni Bajo Giuliani
Telén
[14][13]
Zygolestes tatei Bajo Giuliani [14][21]
Hyperdidelphys sp. Salinas Grandes de Hidalgo [40]
Thylatheridium sp. Estancia Ré
Telén
[15][13]
Didelphinae indet. Telén [13]
Lutreolina sp. Salinas de Hidalgo [12]
Sparassocynidae indet. Telen [14][13]
Ungulates Diplasiotherium pampa Bajo Giuliani
Laguna Chillhué
Salinas de Hidalgo
[12][41]
Eoauchenia cingulata Robilote Field
Salinas de Hidalgo
[12][29]
E. primitiva El Guanaco [41]
Epecuenia thoatherioides Robilote Field
Salinas de Hidalgo
[12][29]
Huayqueriana cristata Robilote Field [29]
Macrauchenia latidens Salinas de Hidalgo
 
[12]
cf. Brachytherium cuspidatum Telén
Salinas de Hidalgo
[12][13]
Neobrachytherium sp. Bajo Giuliani
Salinas de Hidalgo
[12][41]
Promacrauchenia sp. Grünbein Cantera Relleno Sanitario Level 2
Salinas de Hidalgo
[12][27]
Proterotheriidae indet. Bajo Giuliani
Telén
[41][13]
Litopterna indet. Telén [13]
Notoungulata Hemihegetotherium achataleptum Cerro Patagua
Eduardo Castex
Cerro de los Guanacos
Puesto Colorado
Bajo Giuliani
Laguna Chillhué
Loventué
Salinas de Hidalgo
[42][37]
[36][43]
H. lazai Salinas de Hidalgo [12]
Paedotherium bonaerense Barrancas de Sarmiento [27]
Paedotherium minor Laguna La Paraguaya
Estancia Ré
Salinas de Hidalgo
[12][35]
Paedotherium cf. minor Grünbein Cantera Seminario [27]
Pisanodon nazari Salinas de Hidalgo [12]
Pseudotypotherium carhuense Robilote Field
Salinas de Hidalgo
[12][29]
Tremacyllus impressus Grünbein Cantera Seminario
Bajo Giuliani
Laguna Chillhué
Salinas Grandes de Hidalgo
Quehué
Barrancas Coloradas
[27][43]
Typotheriodon grandis Robilote Field [29]
Typotheriopsis minimus Robilote Field [29]
Paedotherium sp. Bajo Giuliani
Laguna Chillhué
Estancia Ré
[44]
Mesotheriinae indet. Laguna La Paraguaya
Telén
[13][35]
Polydolopimorphia Argyrolagus rusconii Bajo Giuliani
El Guanaco
Barrancas Coloradas
[14]
Argyrolagidae indet. Telén [13]
Paucituberculata Pliolestes venetus Bajo Giuliani
Laguna Chillhué
[14]
Birds Phorusrhacidae Devincenzia pozzi Carhué [45]
Procariama simplex Salinas de Hidalgo
 
[46]
Phorusrhacidae indet. Laguna Guatraché
Carhué
[45]
Cathartidae Argentavis magnificens Carhué
 
[12]
Tinamiformes Eudromia sp. Salinas de Hidalgo [45]
Nothura sp. Bajo Giuliani
El Guanaco
Salinas de Hidalgo
[45]
Rheidae Rhea sp. Salinas de Hidalgo [45]
Reptiles Squamata Tupinambis sp. Telén [13]
Testudines Chelidae indet. Telén [13]
Testudinidae indet. Salinas de Hidalgo [47]
Amphibians Ceratophrynidae Lepidobatrachus sp. Quehué [48]

SALMA correlations edit

Huayquerian correlations in South America
Formation Cerro Azul Ituzaingó Paraná Camacho Raigón Andalhuala Chiquimil Las Flores Maimará Palo Pebas Muyu Rosa Saldungaray Salicas Urumaco Map
Basin Colorado Paraná Hualfín Tontal Andes Salta Amazon Huasi Altiplano BA Velasco Falcón
Cerro Azul Formation (South America)
Country   Argentina   Uruguay   Argentina   Brazil
  Peru
  Bolivia   Argentina   Venezuela
Cardiatherium        
Lagostomus            
Macroeuphractus      
Proeuphractus        
Pronothrotherium    
Pseudotypotherium      
Thylacosmilus      
Xotodon        
Macraucheniidae            
Primates  
Rodents                      
Reptiles            
Birds        
Terror birds      
Flora    
Environments Aeolian-fluvial Fluvio-deltaic Fluvial Fluvio-lacustrine Fluvial Fluvio-lacustrine Fluvio-deltaic
  Huayquerian volcanoclastics

  Huayquerian fauna

  Huayquerian flora
Volcanic Yes

See also edit

References edit

  1. ^ a b Cerro Azul Formation in the Paleobiology Database
  2. ^ Epecuén Formation in the Paleobiology Database
  3. ^ a b Visconti et al., 2010, p.259
  4. ^ Visconti et al., 2010, p.262
  5. ^ Carrillo et al., 2015, p.5
  6. ^ Pérez, 2012, p.11
  7. ^ Visconti et al., 2010, p.258
  8. ^ Cardonatto & Melchor, 2018, p.2
  9. ^ Caleufú at Fossilworks.org
  10. ^ Verzi & Montalvo, 2008, p.285
  11. ^ Cardonatto & Melchor, 2018, p.1
  12. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak Vizcaino & Fariña, 1999
  13. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af Montalvo et al., 2008
  14. ^ a b c d e f g h Goin et al., 2000
  15. ^ a b c d e f Montalvo et al., 2016
  16. ^ Vucetich et al., 2014
  17. ^ a b c Verzi, 1999
  18. ^ Montalvo & Rocha, 2003
  19. ^ Verzi et al., 2011
  20. ^ Montalvo & Casadio, 1988
  21. ^ a b c d e f g Verzi et al., 2008
  22. ^ Verzi et al., 1995
  23. ^ Pascual et al., 1965
  24. ^ Verzi et al., 1991
  25. ^ a b Sostillo et al., 2014
  26. ^ Verzi et al., 1994
  27. ^ a b c d e f g h i j k l m n o p q r s t u v Deschamps, 2005
  28. ^ a b Cerdeño et al., 2017
  29. ^ a b c d e f g h i Cabrera, 1939
  30. ^ Zurita & Aramayo, 2007
  31. ^ Montalvo et al., 2020
  32. ^ Rovereto, 1914
  33. ^ a b Goin, 1997
  34. ^ Ortega, 1967
  35. ^ a b c d Cardonatto & Melchor, 2018, p.16
  36. ^ a b c d e f g h i j Urrutia et al., 2008
  37. ^ a b c d e f g h i Esteban et al., 2000
  38. ^ a b c d e f g h i Esteban et al., 2003
  39. ^ Goin & Montalvo, 1988
  40. ^ Goin & Pardiñas, 1996
  41. ^ a b c d Schmidt et al., 2018
  42. ^ Cerdeño & Montalvo, 2002
  43. ^ a b Sostillo et al., 2018
  44. ^ Cerdeño et al., 2017
  45. ^ a b c d e Cenizo et al., 2012
  46. ^ Vezzosi, 2012
  47. ^ De la Fuente et al., 2018
  48. ^ Nicoli, 2017

Bibliography edit

Geology
Paleontology