Santa Juana Formation
Santa Juana Formation a sedimentary rock formation near Santa Juana in the lower course of Biobío River in south-central Chile. Lithologies range from conglomerate sandstone, arkosic sandstone, siltstone and mudstone.[1]
| Santa Juana Formation Stratigraphic range: Carnian | |
|---|---|
| Type | Geological formation |
| Sub-units | Talcamávida-Gomero Member Unihue Member Quilacoya Member |
| Overlies | Coastal Batholith of central Chile |
| Thickness | Unknown |
| Lithology | |
| Primary | conglomerate, sandstone, siltstone, |
| Other | Arkosic sandstone, mudstone, volcanic rock, anthracite |
| Location | |
| Coordinates | 37.2°S 73.0°W |
| Approximate paleocoordinates | 53.8°S 39.9°W |
| Region | Bío Bío Region |
| Country |  |
| Type section | |
| Named for | Santa Juana |
| Named by | Ferraris |
| Year defined | 1981 |
  Santa Juana Formation (Chile) | |
Description
Late Triassic (220 Ma)
The sediments that consolidate into the rocks of the formation deposited in alluvial, fluvial, lacustrine and playa lake environment. Overall the formation is rich in plant fossils.[1]
The formation was deposited over the rocks of the Coastal Batholith of central Chile in a sedimentary basin that formed along the Gastre Fault. It has been posited that the basin developed as a rift during the early break-up of Gondwana in the Triassic.[1]
See also
- Chañares Formation, fossiliferous formation of the Ischigualasto-Villa Unión Basin, Argentina
- Candelária Formation, contemporaneous fossiliferous formation of the Paraná Basin, Brazil
- Molteno Formation, contemporaneous fossiliferous formation of Lesotho and South Africa
- Pebbly Arkose Formation, contemporaneous fossiliferous formation of Botswana, Zambia and Zimbabwe
- Denmark Hill Insect Bed, contemporaneous fossiliferous unit of Queensland, Australia
- Madygen Formation, contemporaneous Lagerstätte of Kyrgyzstan
References
- Nielsen, Sven N. (2005). "The Triassic Santa Juana Formation at the lower Biobío River, south central Chile". Journal of South American Earth Sciences. 19: 547–562. doi:10.1016/j.jsames.2005.06.002.
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