Ischigualasto-Villa Unión Basin
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 |
| 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.