Summary
The Laguna del Hunco Formation or Laguna del Hunco Tuff (Spanish: Formación Laguna del Hunco, Tufolitas Laguna del Hunco) is a localized Early Eocene (Itaboraian in the SALMA classification) fossiliferous geological formation of the Cañadón Asfalto Basin in central Patagonia, Argentina. The 170 metres (560 ft) thick formation comprises tuffaceous mudstones and sandstones deposited in a crater lake environment and crops out at Laguna del Hunco in the northwestern Chubut Province.
| Laguna del Hunco Formation | |
|---|---|
| Stratigraphic range: Ypresian (Itaboraian) ~ | |
| Type | Geological formation |
| Unit of | Middle Chubut River Volcanic Pyroclastic Complex |
| Underlies | Sarmiento Group |
| Overlies | Barda Colorada Ignimbrite |
| Thickness | 170 m (560 ft) |
| Lithology | |
| Primary | Tuff, mudstone, sandstone |
| Location | |
| Coordinates | 42°18′S 70°00′W / 42.3°S 70.0°W |
| Approximate paleocoordinates | 44°48′N 60°00′W / 44.8°N 60.0°W |
| Region | Chubut Province |
| Country | Argentina |
| Extent | Cañadón Asfalto Basin |
| Type section | |
| Named for | Laguna del Hunco |
| Named by | Aragón & Mazzoni |
| Location | Languiñeo Department |
| Year defined | 1997 |
| Coordinates | 42°18′S 70°00′W / 42.3°S 70.0°W |
| Approximate paleocoordinates | 44°48′N 60°00′W / 44.8°N 60.0°W |
| Region | Chubut Province |
| Country | Argentina |
| Thickness at type section | 170 m (560 ft) |
  Laguna del Hunco Formation (Argentina) | |
The formation has been precisely dated to 52.22 ± 0.22 Ma on the basis of sanidine crystals in the tuffs of the formation. The Laguna del Hunco formation overlies the Barda Colorada Ignimbrite and is covered by the Sarmiento Group. The unit is renowned for the preservation of an extraordinarily rich fossil flora assemblage of mixed South American families and presently uniquely Australasian flora, among which the oldest Eucalyptus fossils found worldwide. The formation also has provided many fossil insects, including insect eggs, fossil fish of Bachmannia chubutensis and the frog Shelania pascuali. Periodic bursts of gas in the volcanic crater lake are thought to have produced the sudden death and preservation of the floral and faunal assemblage.
Description edit
The Laguna del Hunco Formation, named after Laguna del Hunco ("Lake of Reeds"), a desert pond in Chubut Province,[1][2] is a localized sedimentary unit comprising tuffaceous sandstones and mudstones with primary and reworked ashfall layers. The formation was deposited in a crater lake environment. The approximately 170 metres (560 ft) thick formation forms part of the Middle Chubut River Volcanic Pyroclastic Complex of the western Cañadón Asfalto Basin.[3] This complex comprises a variety of volcaniclastic, intrusive, pyroclastic, and extrusive rocks, deposited over several million years. The complex is characterized by a great variety of volcanogenic bodies, such as ignimbrites, domes, lava flows, necks, intrusives, tuffs, and volcaniclastic deposits (of predominantly lacustrine origin), all of them frequently interbedded.[4]
The Laguna del Hunco Formation was formerly included in the Huitrera Formation,[5] overlies the Barda Colorada Ignimbrite,[6] and is overlain by the Sarmiento Group.[7] The formation has been dated using 40Ar/39Ar analysis on sanidine crystals of the ash beds to 52.22 ± 0.22 Ma, placing the deposits in the Early Eocene, or Itaboraian in the SALMA classification.[8]
Paleontological significance edit
The paleoflora of the formation is considered one of the most biodiverse Cenozoic fossil deposits worldwide.[9] The biota is composed of extraordinarily rich assemblages of ferns, conifers, and flowering plants, many of which have not yet been formally described.[10] The flora of the formation, studied since the 1920s, was formerly thought to be Miocene in age.[8]
Three described species in the genus Gymnostoma of the family Casuarinaceae,[11] and the species Ceratopetalum edgardoromeroi of the family Cunoniaceae are the only members of these families found outside of Australasia.[12] The floral assemblage is thought to represent a lakeshore vegetation,[2] deposited during the Early Eocene Climatic Optimum (EECO),[13][14] with estimated average yearly temperatures of 17.2 ± 2.3 °C (63.0 ± 4.1 °F) and annual rainfall of 1,673 ± 426 millimetres (65.9 ± 16.8 in).[15] Periodic gas bursts in the crater lake of Laguna del Hunco probably led to the sudden deaths of the flora and fauna found in the formation.[13]
Paleobiota edit
The following fossil plants and animals have been described from the formation:
| Group | Group | Species | Images | references |
|---|---|---|---|---|
| Vertebrates | 2021[16] | |||
| [17] | ||||
| Actinopterygii | Bachmannia chubutensis | [13] | ||
| Invertebrates | Insects |
Austropanorpodes gennaken |
[18] | |
|
Austroperilestes hunco |
[19] | |||
|
Chinchekoala qunita |
[20] | |||
|
Frenguellia iglesiasi |
[21] | |||
|
Frenguellia patagonica |
[22] | |||
|
Huncoaeshna corrugata |
[23] | |||
|
Satelitala soberana |
[24] | |||
|
Urocerus patagonicus |
[25] | |||
| Ichnofossils |
Paleoovoidus arcuatum |
[26] | ||
|
Paleoovoidus bifurcatus |
[26] | |||
|
Paleoovoidus rectus |
[26] | |||
| Flora |
Araucaria pichileufensis |
[27] | ||
|
Austrozamia stockeyi |
[28] | |||
|
Ceratopetalum edgardoromeroi |
[29] | |||
| [30] | ||||
| Myrtaceae | Eucalyptus | [31] | ||
| [32] | ||||
|
Ginkgo patagonica |
[33] | |||
| Casuarinaceae |
Gymnostoma archangelskyi |
[34] | ||
|
Gymnostoma argentinum |
[35] | |||
|
Gymnostoma patagonicum |
[36] | |||
| Proteaceae |
Lomatia occidentalis |
[27] | ||
|
Lomatia preferruginea |
[27] | |||
|
Todea amissa |
[37] | |||
|
Podocarpus andiniformis |
[27] | |||
|
Ripogonum americanum |
[38] | |||
 |
[39] |
References edit
- ^ Wilf et al., 2005, p.635
- ^ a b Wilf et al., 2005, p.636
- ^ Figari et al., 2015, p.154
- ^ Tejedor et al., 2009, p.5
- ^ Zamaloa et al., 2006, p.1280
- ^ Figari et al., 2015, p.153
- ^ Figari et al., 2015, p.155
- ^ a b Carvalho et al., 2013, p.1834
- ^ Gandolfo et al., 2011, p.1
- ^ Laguna del Hunco - Cornell University
- ^ Zamaloa et al., 2006, p.1288
- ^ Gandolfo & Hermsen, 2017, p.9
- ^ a b c Azpelicueta & Cione, 2011
- ^ Sarzetti et al., 2009, p.432
- ^ Dibán Karmy, 2018, p.26
- ^ Degrange et al., 2021, p.6
- ^ Báez & Trueb, 1997
- ^ Petrulevičius, 2009
- ^ Petrulevičius & Nel, 2005
- ^ Petrulevičius, 2016, p.863
- ^ Petrulevičius & Nel, 2013
- ^ Petrulevičius & Nel, 2003
- ^ Petrulevičius et al., 2010, p.273
- ^ Petrulevičius, 2017, p.780
- ^ Petrulevičius, 1999, p.96
- ^ a b c Sarzetti et al., 2009, p.437
- ^ a b c d Wilf et al., 2005, p.639
- ^ Wilf et al., 2016
- ^ Gandolfo & Hermsen, 2017, p.3
- ^ Dibán Karmy, 2018, p.25
- ^ Gandolfo et al., 2011, p.4
- ^ Gandolfo et al., 2011, p.5
- ^ Villar de Seoane et al., 2015, p.4
- ^ Zamaloa et al., 2006, p.1283
- ^ Zamaloa et al., 2006, p.1284
- ^ Zamaloa et al., 2006, p.1281
- ^ Carvalho et al., 2013, p.1835
- ^ Carpenter et al., 2014
- ^ Wilf, P.; Carvalho, M. R.; Gandolfo, M. A.; Cúneo, N. R. (2017). "Eocene lantern fruits from Gondwanan Patagonia and the early origins of Solanaceae". Science. 355 (6320): 71–75. Bibcode:2017Sci...355...71W. doi:10.1126/science.aag2737. PMID 28059765. S2CID 206651318.
Bibliography edit
- Degrange, F. J.; D. Pol; P. Puerta, and P. Wilf. 2021. Unexpected larger distribution of Paleogene stem-rollers (Aves, Coracii): new evidence from the Eocene of Patagonia, Argentina. Scientific Reports 11. Article number 1363. . doi:10.1038/s41598-020-80479-8
Material was copied from this source, which is available under a Creative Commons Attribution 4.0 International License. - Dibán Karmy, María José. 2018. Evolución del nicho climático del género Escallonia Mutis Ex L.F. (Escalloniaceae) en Sudamérica, 1–73. Universidad de Chile. Accessed 2019-03-02.
- Figari, Eduardo G.; Roberto A. Scasso; Rubén N. Cúneo, and Ignacio Escapa. 2015. Estratigrafía y evolución geológica de la Cuenca de Cañadón Asfalto, Provincia del Chubut, Argentina. Latin American Journal of Sedimentology and Basin Analysis 22. 135–169. Accessed 2018-09-10.
- Gandolfo, María A., and Elizabeth J. Hermsen. 2017. Ceratopetalum (Cunoniaceae) fruits of Australasian affinity from the early Eocene Laguna del Hunco flora, Patagonia, Argentina. Annals of Botany 119(4). 507–516. Accessed 2019-03-02.
- Petrulevičius, Julián F. 2017. A new burmagomphid dragonfly from the Eocene of Patagonia, Argentina. Acta Palaeontologica Polonica 62. 779–783. Accessed 2019-03-02.
- Petrulevičius, Julián F. 2016. A new pentatomoid bug from the Ypresian of Patagonia, Argentina. Acta Palaeontologica Polonica 61. 863–868. Accessed 2019-03-02.
- Carpenter, Raymond J.; Peter Wilf; John G. Conran, and N. Rubén Cúneo. 2014. A Paleogene trans-Antarctic distribution for Ripogonum (Ripogonaceae: Liliales)?. Palaeontologia Electronica 17(3). Article number 17.3.39A. Accessed 2019-03-02.
- Carvalho, Mónica R.; Peter Wilf; Elizabeth J. Hermsen; Maria A. Gandolfo; N. Rubén Cúneo, and Kirk R. Johnson. 2013. First record of Todea (Osmundaceae) in South America, from the early Eocene paleorainforests of Laguna del Hunco (Patagonia, Argentina). American Journal of Botany 100(9). 1831–1848. Accessed 2019-03-02.
- Petrulevičius, Julián F., and André Nel. 2013. A new Frenguelliidae (Insecta: Odonata) from the early Eocene of Laguna del Hunco, Patagonia, Argentina. Zootaxa 3616(6). 597–600. Accessed 2019-03-02.
- Petrulevičius, Julián F.; André Nel, and Jean-François Voisin. 2013. A new genus and species of darner dragonfly (Aeshnidae: Odonata) from the lower Eocene of Laguna del Hunco, Patagonia, Argentina. Annales de la Société Entomologique de France 46. 271–275. Accessed 2019-03-02.
- Azpelicueta, M.M., and A.L. Cione. 2011. Redescription of the Eocene Catfish Bachmannia chubutensis (Teleostei: Bachmanniidae) of Southern South America. Journal of Vertebrate Paleontology 31. 258–269. Accessed 2019-03-01.
- Gandolfo, María A.; Elizabeth J. Hermsen; María C. Zamaloa; Kevin C. Nixon; Cynthia C. González; Peter Wilf; N. Rubén Cúneo, and Kirk R. Johnson. 2011. Oldest Known Eucalyptus Macrofossils Are from South America. PLoS ONE 6. 1–9. Accessed 2019-03-02.
- Báez, A.M., and L. Trueb. 1997. Redescription of the Paleogene Shelania pascuali from Patagonia and its bearing on the relationships of fossil and Recent pipoid frogs. Scientific Papers, Natural History Museum, University of Kansas 4. 1–41. Accessed 2019-03-01. Archived 2019-03-02 at the Wayback Machine
- Petrulevičius, Julián F. 2009. A Panorpoid (Insecta: Mecoptera) from the Lower Eocene of Patagonia, Argentina. Journal of Paleontology 83. 994–997. Accessed 2019-03-02.
- Petrulevičius, Julián F., and André Nel. 2005. Austroperilestidae, a new family of damselflies from the earliest Eocene of Argentina (Insecta: Odonata). Phylogenetic relationships within Odonata. Journal of Natural History 37. 2909–2917. Accessed 2019-03-02.
- Petrulevičius, Julián F., and André Nel. 2003. Frenguelliidae, a new family of dragonflies from the earliest Eocene of Argentina (Insecta: Odonata): Phylogenetic relationships within Odonata. Journal of Natural History 37. 2909–2917. Accessed 2019-03-02.
- Petrulevičius, Julián F. 1999. Insectos del Cenozóico de la Argentina. Revista de la Sociedad Entomológica de Argentina 58. 95–103. Accessed 2019-03-02.
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- Villar de Seoane, Liliana; Cúneo N. Rubén; Ignacio Escapa; Peter Wilf, and María A. Gandolfo. 2015. Ginkgoites patagonica (Berry) comb. nov. from the Eocene of Patagonia, Last Ginkgoalean Record in South America. International Journal of Plant Sciences 176. 1–18. Accessed 2019-03-02.
- Wilf, Peter; Dennis Wm. Stevenson, and N. Rubén Cúneo. 2016. The last Patagonian cycad, Austrozamia stockeyi gen. et sp. nov., early Eocene of Laguna del Hunco, Chubut, Argentina. Botany 94(9). 817–829. Accessed 2019-03-02.
- Wilf, Peter; Kirk R. Johnson; N. Rubén Cúneo; M. Elliot Smith; Bradley S. Singer, and Maria A. Gandolfo. 2005. Eocene Plant Diversity at Laguna del Hunco and Río Pichileufú, Patagonia, Argentina. The American Naturalist 135. 634–650. Accessed 2017-10-26.
- Zamaloa, Maria del C.; Maria A. Gandolfo; Cynthia C. González; Edgardo J. Romero; Néstor R. Cúneo, and Peter Wilf. 2006. Casuarinaceae from the Eocene of Patagonia, Argentina. International Journal of Plant Sciences 167. 1279–1289. Accessed 2019-03-02.