Laguna del Hunco Formation
The Laguna del Hunco Formation or Laguna del Hunco Tuff () is a localized Early Eocene (Itaboraian in the SALMA classification) fossiliferous geological formation of the Cañadón Asfalto Basin in central Patagonia, Argentina. The 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.
Q76274
Early Eocene
TIME
Q6092292
Itaboraian
TIME
Q5817530
SALMA classification
Concept
None
fossiliferous
UNK
Q736917
geological formation
Concept
Q65047273
Cañadón Asfalto Basin
UNK
Q1507
Patagonia
LOC
Q414
Argentina
LOC
Q484924
tuff
Concept
Q6642424
mudstone
Concept
Q13085
sandstone
Concept
Q204324
crater lake
Concept
Q1994702
environment
UNK
Q531953
crops out
Concept
None
Laguna del Hunco
UNK
Q45007
Chubut Province
LOC
Q426723
sanidine
Concept
None
Barda Colorada Ignimbrite
UNK
None
Sarmiento Group
UNK
Q1077944
Australasian
Concept
Q45669
Eucalyptus
Concept
Q1390
insect
Concept
Q16726069
Bachmannia chubutensis
MISC
Q7493310
Shelania pascuali
Concept
Q85775559
Laguna del Hunco Formation
UNK
+52.22^^http://www.w3.org/2001/XMLSchema#decimal
52.22
NUMBER
+0.22^^http://www.w3.org/2001/XMLSchema#decimal
0.22
NUMBER
instance of
located in the administrative territorial entity