The Cañadón Asfalto Formation is a Lower Jurassic to Late Jurassic geologic formation, from the Jurassic period of the Mesozoic Era. Its age is controversial, uranium-lead dating of the volcanic tuff beds having given various different ages. A Recent work suggested that the base of the formation was formed around 171 Ma, during the upper Aalenian, while the main age for the Lower Las Chacritas Member being around 168 Ma, during the Bajocian, Bathonian and Callovian While the overlying Puesto Almada Member seems to be around 158 ma, or Oxfordian age, that changed thanks to the discovery of zircons near the location of discovery of ''

Bagualia ''Bagualia'' (meaning "wild horse" in Spanish, after Bagual Canyon, the type locality), is an extinct genus of eusauropod dinosaur, from the Early Jurassic Epoch in what is now Argentina. The type species, ''B. alba'', was formally described in ...

'', allowing a precise age of Las Charcitas Member as Middle-Late Toarcian, 178-179 million years, and a later study constrained the age of the formation as Middle Toarcian-Lower Bajocian, being contemporaneous to the

Chon Aike CHON is a mnemonic acronym for the four most common elements in living organisms: carbon, hydrogen, oxygen, and nitrogen. The acronym CHNOPS, which stands for ''c''arbon, ''h''ydrogen, ''n''itrogen, ''o''xygen, ''p''hosphorus, ''s''ulfur, r ...

volcanic activity, being a local equivalent to Antarctica's Mawson Formation. It is located in the Cañadón Asfalto Basin, a rift basin in Chubut Province of northwestern Patagonia, in southern Argentina. The basin started forming in the earliest Jurassic.Figari et al., 2015, p.142 It is composed of fluvial-

lacustrine deposits Lacustrine deposits are sedimentary rock formations which formed in the bottom of ancient lakes. A common characteristic of lacustrine deposits is that a river or stream channel has carried sediment into the basin. Lacustrine deposits form in all ...

, typically sandstones and shales with a saline paleolake carbonate evaporitic sequence of limestone in its lowest Las Chacritas Member. Interbedded with these are volcanic tuffites. It is divided into two members, the Las Chacritas Member, and the overlying Puesto Almada member, but the latter has also been assigned to the overlying

Cañadón Calcáreo Formation The Cañadón Calcáreo Formation is an Oxfordian to Kimmeridgian-aged geologic formation, from the Cañadón Asfalto Basin in Chubut Province, Argentina, a rift basin that started forming since the earliest Jurassic.Figari et al., 2015, p.142 It ...

by other authors. According to a palynological study, the dominant pollen was produced by the conifer families Cheirolepidiaceae (''Classopollis'') and Araucariaceae (mainly ''Araucariacites'' and ''Callialasporites''), suggesting that warm-temperate and relatively humid conditions under highly seasonal climate prevailed during the depositional times of the unit. The abundance of ''Botryococcus'' supports the presence of a shallow lake with probably saline conditions.

Vertebrate fauna

Amphibians

Turtles

Lepidosaurs

Pterosaurs

Crocodylomorpha

Dinosaurs

Mammals

Plant remains

References

Bibliography

* * {{DEFAULTSORT:Canadon Asfalto Formation Geologic formations of Argentina Jurassic System of South America Sandstone formations Limestone formations Shale formations Conglomerate formations Tuff formations Fluvial deposits Lacustrine deposits Jurassic paleontological sites Mesozoic paleontological sites of South America Fossiliferous stratigraphic units of South America Paleontology in Argentina Geology of Chubut Province