Earth:Santa Juana Formation

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Santa Juana Formation
Stratigraphic range: Carnian
~235–222 Ma
TypeGeological formation
Sub-unitsTalcamávida-Gomero, Unihue & Quilacoya Members
OverliesCoastal Batholith of central Chile
ThicknessUnknown
Lithology
PrimaryConglomerate, sandstone, siltstone
OtherArkosic sandstone, mudstone, volcanic rock, anthracite
Location
Coordinates [ ⚑ ] : 37°12′S 73°00′W / 37.2°S 73.0°W / -37.2; -73.0
Paleocoordinates [ ⚑ ] 53°48′S 39°54′W / 53.8°S 39.9°W / -53.8; -39.9
RegionBío Bío Region
Country Chile
Type section
Named forSanta Juana
Named byFerraris
Year defined1981
Santa Juana Formation is located in Chile
Santa Juana Formation
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


Insects

  • Bandelnielsenia chilena[4]
  • Ischichucasyne santajuanaensis[4]
  • Ademosyne sp.[4]


Branchiopoda

See also


References

Bibliogahy

  • Moisan, P.; E. Abad; B. Bomfleur, and H. Kerp. 2010. A Late Triassic flora from Gomero (Santa Juana Formation), Chile. Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen 258. 89–106.
  • 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
  • Martins Neto, R. G.; O. F. Gallego, and R. N. Melchor. 2003. The Triassic insect fauna from South America (Argentina, Brazil and Chile): a checklist (except Blattoptera and Coleoptera) and descriptions of new taxa. Acta Zoologica Cracoviensia 46 (Suppl). 229–256.