Laguna del Hunco Formation

Laguna del Hunco Formation
Laguna del Hunco Formation
Stratigraphic range: Ypresian; (Itaboraian); ~52.44–52 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
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	Lua error in Module:Coordinates at line 489: attempt to index field 'wikibase' (a nil value).
Approximate paleocoordinates	Lua error: callParserFunction: function "#coordinates" was not found.
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	Lua error: callParserFunction: function "#coordinates" was not found.
Approximate paleocoordinates	Lua error: callParserFunction: function "#coordinates" was not found.
Region	Chubut Province
Country	Argentina
Thickness at type section	170 m (560 ft)
	Laguna del Hunco Formation (Argentina)

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.

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

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

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

The following fossil plants and animals have been described from the formation:

Group	Group	Species	Images	references
Vertebrates	Aves	Ueekenkcoracias tambussiae		2021^[16]
	Amphibia	Shelania pascuali		^[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	Araucariaceae	Araucaria pichileufensis		^[27]
	Cycads	Austrozamia stockeyi		^[28]
	Cunoniaceae	Ceratopetalum edgardoromeroi		^[29]
	Escalloniaceae	Escallonia		^[30]
	Myrtaceae	Eucalyptus		^[31]
	Myrtaceae	Eucalyptus		^[32]
	Ginkgoaceae	Ginkgo patagonica		^[33]
	Casuarinaceae	Gymnostoma archangelskyi		^[34]
		Gymnostoma argentinum		^[35]
		Gymnostoma patagonicum		^[36]
	Proteaceae	Lomatia occidentalis		^[27]
	Proteaceae	Lomatia preferruginea		^[27]
	Osmundaceae	Todea amissa		^[37]
	Podocarpaceae	Podocarpus andiniformis		^[27]
	Ripogonaceae	Ripogonum americanum		^[38]
	Solanaceae	Physalis infinemundi	Physalis infinemundi	^[39]
	Malvaceae	Uiher karuen		^[40]

References

^ 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
^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
^ Siegert et al., 2024

Bibliography

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[Wilf2005_p635-1] Wilf et al., 2005, p.635

[Wilf2005_p636-2] Wilf et al., 2005, p.636

[Figari2015_p154-3] Figari et al., 2015, p.154

[Tejedor2009_p5-4] Tejedor et al., 2009, p.5

[Zamaloa2006_p1280-5] Zamaloa et al., 2006, p.1280

[Figari2015_p153-6] Figari et al., 2015, p.153

[Figari2015_p155-7] Figari et al., 2015, p.155

[Carvalho2013_p1834-8] Carvalho et al., 2013, p.1834

[Gandolfo2011_p1-9] Gandolfo et al., 2011, p.1

[CornellLagunaDelHunco-10] Laguna del Hunco - Cornell University

[Zamaloa2006_p1288-11] Zamaloa et al., 2006, p.1288

[Gandolfo2017_p9-12] Gandolfo & Hermsen, 2017, p.9

[Azpelicueta2011-13] Azpelicueta & Cione, 2011

[Sarzetti2009_p432-14] Sarzetti et al., 2009, p.432

[Diban2018_p26-15] Dibán Karmy, 2018, p.26

[Degrange2021-p6-16] Degrange et al., 2021, p.6

[Baez1997-17] Báez & Trueb, 1997

[Petrulevicius2009-18] Petrulevičius, 2009

[Petrulevicius2005-19] Petrulevičius & Nel, 2005

[Petrulevicius2017_p863-20] Petrulevičius, 2016, p.863

[Petrulevicius2013-21] Petrulevičius & Nel, 2013

[Petrulevicius2003-22] Petrulevičius & Nel, 2003

[Petrulevicius2010_p273-23] Petrulevičius et al., 2010, p.273

[Petrulevicius2017_p780-24] Petrulevičius, 2017, p.780

[Petrulevicius1999_p96-25] Petrulevičius, 1999, p.96

[Sarzetti2009_p437-26] Sarzetti et al., 2009, p.437

[Wilf2005_p639-27] Wilf et al., 2005, p.639

[Wilf2016-28] Wilf et al., 2016

[Gandolfo2017_p3-29] Gandolfo & Hermsen, 2017, p.3

[Diban2018_p25-30] Dibán Karmy, 2018, p.25

[Gandolfo2011_p4-31] Gandolfo et al., 2011, p.4

[Gandolfo2011_p5-32] Gandolfo et al., 2011, p.5

[Villar2015_p4-33] Villar de Seoane et al., 2015, p.4

[Zamaloa2006_p1283-34] Zamaloa et al., 2006, p.1283

[Zamaloa2006_p1284-35] Zamaloa et al., 2006, p.1284

[Zamaloa2006_p1281-36] Zamaloa et al., 2006, p.1281

[Carvalho2013_p1835-37] Carvalho et al., 2013, p.1835

[Carpenter2014-38] Carpenter et al., 2014

[39] Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).

[Siegert2024-40] Siegert et al., 2024

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Laguna del Hunco Formation

Contents

Description

Paleontological significance

Paleobiota

References

Bibliography

Navigation menu

Laguna del Hunco Formation
Stratigraphic range: Ypresian (Itaboraian) ~52.44–52 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
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	Lua error in Module:Coordinates at line 489: attempt to index field 'wikibase' (a nil value).
Approximate paleocoordinates	Lua error: callParserFunction: function "#coordinates" was not found.
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	Lua error: callParserFunction: function "#coordinates" was not found.
Approximate paleocoordinates	Lua error: callParserFunction: function "#coordinates" was not found.
Region	Chubut Province
Country	Argentina
Thickness at type section	170 m (560 ft)
Laguna del Hunco Formation (Argentina)

Laguna del Hunco Formation

Description

Paleontological significance

Paleobiota

References

Bibliography

Navigation menu

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