The Ischigualasto-Villa Unión Basin (Spanish: Cuenca de Ischigualasto-Villa Unión) is a small sedimentary basin located in the Argentine Northwest, Argentina. It is located in the southwestern part of La Rioja Province and the northeastern part of San Juan Province. The basin borders the Sierras Pampeanas in the east, the western boundary of the basin is formed by the Valle Fértil Fault, bordering the Precordillera, and it is bound in the southeast by the El Alto Fault, separating the basin from the Marayes-El Carrizal Basin.
| Ischigualasto-Villa Unión Basin | |
|---|---|
| Cuenca de Ischigualasto-Villa Unión | |
  Location of the basin in Argentina | |
 Geologic map of the Ischigualasto-Villa Unión Basin - detail | |
| Coordinates | 29°32′S 68°05′W / 29.533°S 68.083°W |
| Location | Southern South America |
| Region | Argentine Northwest |
| Country |  Argentina |
| State(s) | La Rioja & San Juan Provinces |
| Cities | Villa Unión |
| Characteristics | |
| On/Offshore | Onshore |
| Boundaries | Sierras Pampeanas (N & E), El Alto Fault (SE), Valle Fértil Fault (W) |
| Part of | Triassic rift basins |
| Area | ~80,000 km2 (31,000 sq mi) |
| Hydrology | |
| River(s) | Talampaya River |
| Geology | |
| Basin type | Rift |
| Plate | South American |
| Orogeny | Break-up of Pangea (Early Triassic) Andean (Cenozoic) |
| Age | Late Permian-Late Triassic |
| Stratigraphy | Stratigraphy |
The basin started forming in the Late Permian, with the break-up of Pangea, when extensional tectonics, including rifting, formed several basins in Gondwana; present-day South America, Africa, Antarctica, India and Australia. The accommodation space in the Ischigualasto-Villa Unión Basin was filled by an approximately 3.5 kilometres (11,000 ft) thick succession of volcaniclastic, eolian, alluvial, fluvial and lacustrine deposits in various geologic formations. The Cenozoic evolution of the basin is mainly influenced by the Andean orogeny, producing folding and faulting in the basin.
The basin is of paleontological significance as it hosts several fossiliferous stratigraphic units providing many fossils of early dinosaurs, synapsids, turtles, mammals, the earliest crocodylomorphs, fish, amphibians and flora, as well as ichnofossils. The Ischigualasto Provincial Park and Talampaya National Park in the basin were designated UNESCO World Heritage Sites in 2000.
Description edit
The Ischigualasto-Villa Unión was recognized as a sedimentary basin by Stipanicic and Bonaparte in 1979. The basin stretches across a small area in northeastern San Juan Province and southwestern La Rioja Province in northwestern Argentina. The basin is bound by the Valle Fértil Fault to the west, separating the basin from the Precordillera, and the El Alto Fault in the southeast, forming the boundary with the Marayes-El Carrizal Basin. To the northeast, the basin ranges to the Sierras Pampeanas.[1] The basin is a rift basin that started forming early in the break-up of Pangea and its southern latitude paleocontinent Gondwana in the Late Permian to Early Triassic, providing a sedimentary column of approximately 3.5 kilometres (11,000 ft) of Triassic sediments.[2]
The area of the basin is sparsely populated, with Villa Unión in the north of the basin. The Talampaya and Chañares Rivers cross the basin.
Stratigraphy edit
The stratigraphy of the Ischigualasto-Villa Unión Basin contains sediments of the Triassic. The earliest deposition occurred in the Early Triassic (Olenekian) with the redbeds of the Talampaya and Tarjados Formations. This sequence is separated from the overlying Agua de la Peña Group by a regional unconformity.[3]
| Age | Group | Formation | Sequence | Environment | Maximum thickness |
Notes |
|---|---|---|---|---|---|---|
| Quaternary | alluvium | |||||
| Neogene | Hiatus | |||||
| Paleogene | ||||||
| Cretaceous | ||||||
| Jurassic | ||||||
| Norian | Agua de la Peña | Los Colorados Formation | Second post-rift | Fluvial-lacustrine | 1,000 m (3,300 ft) | [4][5] |
| Carnian | Ischigualasto Formation | Second syn-rift | Floodplain | 900 m (3,000 ft) | [4] | |
| Los Rastros Formation | First post-rift | Deltaic-lacustrine | 1,000 m (3,300 ft) | [4] | ||
| Chañares Formation / Ischichuca Formation | First syn-rift | Fluvial-lacustrine | 70 m (230 ft) | [4] | ||
| Angular unconformity | ||||||
| Early-Mid Triassic | Paganzo | Tarjados Formation | Pre-rift | Arid fluvial | 250 m (820 ft) | [4][6] |
| Olenekian | Talampaya Formation | Aeolian-fluvial | 400 m (1,300 ft) | [4] | ||
| Angular unconformity | ||||||
| Paleozoic | Basement | Tuminico Formation | [7] | |||
| Precambrian | Valle Fértil Complex | [8] | ||||
Paleontological significance edit
The Ischigualasto-Villa Unión Basin is renowned for hosting the Triassic-age lagerstätten of the Chañares and Ischigualasto formations. These units have produced numerous fossils of synapsids and reptiles, including the earliest known dinosaurs. Other fossiliferous units within the basin have preserved fish, insects, flora, and ichnofossils. The basin represents one of three locations in Argentina where Triassic trackways were found, together with the Cuyo Basin to the south and Los Menucos Basin in Río Negro Province.[9]
Many of the earliest known crocodylomorphs come from the Ischigulasto-Villa Unión Basin. In the Los Colorados Formation, the crocodylomorphs Hemiprotosuchus leali and Coloradisuchus abelini were found.[10][11]
See also edit
- Paraná Basin, containing many Triassic fossiliferous formations in southeastern Brazil and northwestern Argentina
- Cuyo Basin, of northwestern Argentina
- Salta Basin, of northwestern Argentina
- Neuquén Basin, of western Argentina
- Cañadón Asfalto Basin, of central-southern Argentina
References edit
- ^ Spalletti, 1997, p.37
- ^ Schencman, 2015, p.220
- ^ Arcucci et al., 2004, p.558
- ^ a b c d e f Aceituno Cieri et al., 2015, p.60
- ^ Kent et al, 2014, p.7959
- ^ Balabusic et al., 2001, p.28
- ^ Aceituno Cieri et al., 2015, p.59
- ^ Monetta et al., 2000, p.647
- ^ Citton et al., 2018, p.5
- ^ Martínez et al., 2018, p.1
- ^ Arcucci et al., 2004, p.561
Bibliography edit
- General
- Aceituno Cieri, P.; M.E. Zeballos; R.J. Rocca; R.D. Martino, and C. Carignano. 2015. Condicionantes geológicos en el cruce de la sierra de Valle Fértil. San Juan - Geological constraints at the crossing of sierra Valle Fertil. San Juan. Revista de Geología Aplicada a la Ingeniería y al Ambiente 35. 57–69. .
- Balabusic, Ana M., et al. 2001. Plan de Manejo del Parque Nacional Talampaya, 1–68. Administración de Parques Nacionales. Accessed 2019-03-28.
- Caselli, Alberto Tomás. 1998. Estratigrafía y sedimentología de las formaciones Patquía (Pérmico) y Talampaya (Triásico Inferior), en las Sierras Pampeanas Noroccidentales y Precordillera Central (Provincias de La Rioja y San Juan) (PhD thesis), 1–437. Universidad de Buenos Aires. Accessed 2019-03-28.
- Milana, Juan Pablo, and Oscar A. Alcober. 1994. Modelo tectosedimentario de la cuenca triásica de Ischigualasto (San Juan, Argentina). Revista de la Asociación Geológica Argentina 49. 217–235. Accessed 2019-03-28.
- Mancuso, Adriana C.; Cecilia A. Benavente; Randall B. Irmis, and Roland Mundil. 2020. Evidence for the Carnian Pluvial Episode in Gondwana: New multiproxy climate records and their bearing on early dinosaur diversification. Gondwana Research in press. . . doi:10.1016/j.gr.2020.05.009
- Monetta, A.; J. Baraldo; A. Cardinali; R. Weidmann, and M. Lanzilotti. 2000. [[1] Distribución y características del magmatismo intratriasico de Ischigualasto, San Juan, Argentina], 644–648. IX Congreso Geológico Chileno. Accessed 2019-03-28.
- Schencman, Laura Jazmín; Carina Colombi; Paula Santi Malnis, and Carlos Oscar Limarino. 2015. Diagenesis and provenance of the Los Colorados formation (Norian), Ischigualasto- Villa Unión basin, Northwest of Argentina. Revista de la Asociación Geológica Argentina 72. 219–234. Accessed 2019-03-28.
- Spalletti, L.A. 1997. Cuencas triásicas del Oeste argentino: origen y evolución - Western Argentinian Triassic basins: origin and evolution. Acta Geológica Hispánica 32. 29–50. Accessed 2019-03-28.
- Paleontology
- Citton, Paolo; Ignacio Díaz Martínez; Silvina De Valais, and Carlos Cónsole Gonella. 2018. Triassic pentadactyl tracks from the Los Menucos Group (Río Negro province, Patagonia Argentina): possible constraints on the autopodial posture of Gondwanan trackmakers. PeerJ 5358. 1–36. Accessed 2019-03-25.
- Leonardi, Giuseppe. 1994. Annotated Atlas of South America Tetrapod Footprints (Devonian to Holocene) with an appendix on Mexico and Central America, 1–248. Ministerio de Minas e Energia - Companhia de Pesquisa de Recursos Minerais, Geological Service of Brazil. Accessed 2019-03-28.
- Chañares Formation
- Arcucci, Andrea; Elena Previtera, and Adriana C. Mancuso. 2019. Ecomorphology and bone microstructure of Proterochampsia from the Chañares Formation. Acta Palaeontologica Polonica 64. 157–170. Accessed 2019-03-28.
- Pérez Loinaze, Valeria Susana; Ezequiel Ignacio Vera; Lucas Ernesto Fiorelli, and Julia Brenda Desojo. 2018. Palaeobotany and palynology of coprolites from the Late Triassic Chañares Formation of Argentina: implications for vegetation provinces and the diet of dicynodonts. Palaeogeography, Palaeoclimatology, Palaeoecology 502. 31–51. Accessed 2018-09-08.
- Los Colorados Formation
- Arcucci, A.B.; C.A. Marsicano, and A.T. Caselli. 2004. Tetrapod association and palaeoenvironment of the Los Colorados Formation (Argentina): a significant sample from western Gondwana at the end of the Triassic. Geobios 37. 557–568. Accessed 2019-03-28.
- Ezcurra, Martín D. 2017. A new early coelophysoid neotheropod from the Late Triassic of northwestern Argentina. Ameghiniana 54. Abstract. Accessed 2019-03-26.
- Fiorelli, Lucas E.; Sebastián Rocher; Agustín G. Martinelli; Martín D. Ezcurra; E. Martín Hechenleitner, and Miguel Ezpeleta. 2018. Tetrapod burrows from the Middle–Upper Triassic Chañares Formation (La Rioja, Argentina) and its palaeoecological implications. Palaeogeography, Palaeoclimatology, Palaeoecology 496. 85–102. Accessed 2018-09-08.
- Kent, Dennis V.; Paula Santi Malnis; Carina E. Colombi; Oscar A. Alcober, and Ricardo N. Martínez. 2014. Age constraints on the dispersal of dinosaurs in the Late Triassic from magnetochronology of the Los Colorados Formation (Argentina). Proceedings of the National Academy of Sciences 111. 7958–7963. Accessed 2018-09-08.
- Martínez, Ricardo N.; Oscar A. Alcober, and Diego Pol. 2018. A new protosuchid crocodyliform (Pseudosuchia, Crocodylomorpha) from the Norian Los Colorados Formation, northwestern Argentina. Journal of Vertebrate Paleontology 38. 1–12. Accessed 2019-03-28.
- Los Rastros Formation
- Martins Neto, R.G.; A. Mancuso, and O.F. Gallego. 2005. The Triassic Insect Fauna from Argentina. Blattoptera from the Los Rastros Formation (Bermejo Basin), La Rioja Province. Ameghiniana 42. 1–21. Accessed 2019-03-28.
Further reading edit
- Bally, A.W., and S. Snelson. 1980. Realms of subsidence. Canadian Society for Petroleum Geology Memoir 6. 9–94. .
- Kingston, D.R.; C.P. Dishroon, and P.A. Williams. 1983. Global Basin Classification System. AAPG Bulletin 67. 2175–2193. Accessed 2017-06-23.
- Klemme, H.D. 1980. Petroleum Basins - Classifications and Characteristics. Journal of Petroleum Geology 3. 187–207. Accessed 2017-06-23.