Santa Juana Formation
Santa Juana Formation Stratigraphic range: Carnian ~ | |
---|---|
Type | Geological formation |
Sub-units | Talcamávida-Gomero, Unihue & Quilacoya Members |
Overlies | Coastal Batholith of central Chile |
Thickness | Unknown |
Lithology | |
Primary | Conglomerate, sandstone, siltstone |
Other | Arkosic sandstone, mudstone, volcanic rock, anthracite |
Location | |
Coordinates | 37°12′S 73°00′W / 37.2°S 73.0°WCoordinates: 37°12′S 73°00′W / 37.2°S 73.0°W |
Approximate paleocoordinates | 53°48′S 39°54′W / 53.8°S 39.9°W |
Region | Bío Bío Region |
Country | Chile |
Type section | |
Named for | Santa Juana |
Named by | Ferraris |
Year defined | 1981 |
Santa Juana Formation (Chile) |
Santa Juana Formation a Late Triassic (Carnian stage) sedimentary rock formation near Santa Juana in the lower course of the Biobío River in south-central Chile.[1] Lithologies range from conglomerate sandstone, arkosic sandstone, siltstone and mudstone.[2]
Description[]
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.[2]
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.[2]
Fossil content[]
The following fossils have been reported from the formation:[1]
Flora[]
- Asterotheca fuchsii[2]
- A. rigbyana[3]
- Baiera africana[3]
- B. furcata[3]
- Cladophlebis mendozaensis[3]
- Dicroidium coriaceum[3]
- D. crassinervis[2]
- D. elongatum[2]
- D. odontopteroides[2][3]
- [2]
- [2][3]
- [3]
- [2]
- [2][3]
- [2]
- [3]
- [2]
- Pterophyllum santajuanensis[2][3]
- [2]
- [2]
- Sphenobaiera africana[2]
- Sphenopteris cf. polymorpha[3]
- [3]
- [3]
- Telemachus elongatus[2]
- [2]
- [3]
- cf. Pseudoctenis fissa[2]
- Cladophlebis sp.[2][3]
- Dicroidium sp.[2]
- [2]
- [2]
Insects[]
Branchiopoda[]
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[]
Bibliogahy[]
- Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen 258. 89-106. ; ; , and . 2010. A Late Triassic flora from Gomero (Santa Juana Formation), Chile.
- 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 . 2005.
- ; , and . 2003. The Triassic insect fauna from South America (Argentina, Brazil and Chile): a checklist (except Blattoptera and Coleoptera) and descriptions of new taxa. 46 (Suppl). 229-256.
- Geologic formations of Chile
- Triassic System of South America
- Late Triassic South America
- Carnian Stage
- Triassic Chile
- Sandstone formations
- Siltstone formations
- Conglomerate formations
- Alluvial deposits
- Fluvial deposits
- Lacustrine deposits
- Paleontology in Chile
- Geology of Biobío Region