The Talampaya Formation is an

Early Triassic The Early Triassic is the first of three epochs of the Triassic Period of the geologic timescale. It spans the time between 251.9 Ma and Ma (million years ago). Rocks from this epoch are collectively known as the Lower Triassic Series, which ...

(

Olenekian In the geologic timescale, the Olenekian is an age (geology), age in the Early Triassic epoch (geology), epoch; in chronostratigraphy, it is a stage (stratigraphy), stage in the Lower Triassic series (stratigraphy), series. It spans the time betw ...

) geologic formation in the Ischigualasto-Villa Unión Basin of La Rioja Province in northwestern

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

. The pink to red

sandstone Sandstone is a Clastic rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains, Cementation (geology), cemented together by another mineral. Sand ...

s of the formation represent the oldest sedimentary unit in the basin, overlying

basement A basement is any Storey, floor of a building that is not above the grade plane. Especially in residential buildings, it often is used as a utility space for a building, where such items as the Furnace (house heating), furnace, water heating, ...

rock and were deposited in a high-energy

braided river A braided river (also called braided channel or braided stream) consists of a network of river channel (geography), channels separated by small, often temporary, islands called ''braid bars'' or, in British English usage, ''aits'' or ''eyots''. ...

environment. Ichnofossils, probably left by an

archosaur Archosauria () or archosaurs () is a clade of diapsid sauropsid tetrapods, with birds and crocodilians being the only extant taxon, extant representatives. Although broadly classified as reptiles, which traditionally exclude birds, the cladistics ...

chirotherian, were found in the formation. The formation crops out in the

Talampaya National Park Talampaya National Park () is a National Parks of Argentina, national park located in the east/centre of La Rioja Province (Argentina), La Rioja Province, Argentina. It was designated a provincial reserve in 1975, a national park in 1997, and a U ...

, which was designated a

UNESCO The United Nations Educational, Scientific and Cultural Organization (UNESCO ) is a List of specialized agencies of the United Nations, specialized agency of the United Nations (UN) with the aim of promoting world peace and International secur ...

World Heritage Site World Heritage Sites are landmarks and areas with legal protection under an treaty, international treaty administered by UNESCO for having cultural, historical, or scientific significance. The sites are judged to contain "cultural and natural ...

in 2000.

Description

The formation was first defined by Romer and Jensen in 1966,Caselli, 1998, p.22 based on a type section exposed in the

Talampaya River Talampaya National Park () is a national park located in the east/centre of La Rioja Province, Argentina. It was designated a provincial reserve in 1975, a national park in 1997, and a UNESCO World Heritage Site in 2000. Location The park prote ...

canyon A canyon (; archaic British English spelling: ''cañon''), gorge or chasm, is a deep cleft between escarpments or cliffs resulting from weathering and the erosive activity of a river over geologic time scales. Rivers have a natural tendency t ...

.Caselli, 1998, p.23 The Talampaya Formation belongs to the Paganzo Group.Leonardi, 1994, p.19 The formation represents the oldest sedimentary unit in the Ischigualasto-Villa Unión Basin in the

of La Rioja Province, overlying

Paleozoic The Paleozoic ( , , ; or Palaeozoic) Era is the first of three Era (geology), geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds the Neoproterozoic (the last era of the Proterozoic Eon) and ends 251.9 Ma a ...

, formed by the Tuminico Formation.Aceituno Cieri et al., 2015, p.59 The Talampaya Formation is overlain by the

arid Aridity is the condition of geographical regions which make up approximately 43% of total global available land area, characterized by low annual precipitation, increased temperatures, and limited water availability.Perez-Aguilar, L. Y., Plata ...

fluvial A river is a natural stream of fresh water that flows on land or inside caves towards another body of water at a lower elevation, such as an ocean, lake, or another river. A river may run dry before reaching the end of its course if it ru ...

sandstones and conglomerates of the Tarjados Formation, eroding the Talampaya Formation.Balabusic et al., 2001, p.26 The formation, reaching a maximum thickness of with a general thickness of approximately ,Aceituno Cieri et al., 2015, p.60Monetta et al., 2000, p.648 comprises pink to reddish

s,Talampaya Formation
/ref> deposited in a

environment, dominated by high-energy

s producing sheet floods.Caselli, 1998, p.147Balabusic et al., 2001, p.25 The sediments were deposited under uniform climatic conditions with temperate to warm temperatures and high humidity.Balabusic et al., 2001, p.28 Other

facies In geology, a facies ( , ; same pronunciation and spelling in the plural) is a body of rock with distinctive characteristics. The characteristics can be any observable attribute of rocks (such as their overall appearance, composition, or con ...

recognized in the formation are

alluvial fan An alluvial fan is an accumulation of sediments that fans outwards from a concentrated source of sediments, such as a narrow canyon emerging from an escarpment. They are characteristic of mountainous terrain in arid to Semi-arid climate, semiar ...

deposits with thin

tuff Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock co ...

aceous beds and conglomerates, covered by a section of

basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

is and other volcanic agglomerates and eolian sandstones.Caselli, 1998, p.24 Tetrapod ichnofossils, probably belonging to a chirotherian (and possibly an

), were discovered in the formation southeast of Pagancillo by Argentina paleontologist José Bonaparte in 1964.

References

Bibliography

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Description

See also

References

Bibliography

Further reading