Santa Juana Formation
Santa Juana Formation a Late Triassic sedimentary rock formation near Santa Juana in the lower course of the Biobío River in south-central Chile. Lithologies range from conglomerate sandstone, arkosic sandstone, siltstone and mudstone.
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.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.
Fossil content
The following fossils have been reported from the formation:Flora
- Asterotheca fuchsii
- A. rigbyana
- Baiera africana
- B. furcata
- Cladophlebis mendozaensis
- Dicroidium coriaceum
- D. crassinervis
- D. elongatum
- D. odontopteroides
- Dictyophyllum fuenzalidai
- D. tenuifolium
- Gleichenites quilacoyensis
- Gontriglossa reinerae
- Heidiphyllum elongatum
- Kurtziana cacheutensis
- Linguifolium lilleanum
- L. steinmannii
- Pterophyllum santajuanensis
- Rissikia media
- Saportaea dichotoma
- Sphenobaiera africana
- Sphenopteris cf. polymorpha
- Taeniopteris sp.
- Taeniopteris vittata
- Telemachus elongatus
- Thaumatopteris rothii
- Todites chilensis
- cf. Pseudoctenis fissa
- Cladophlebis sp.
- Dicroidium sp.
- Gleichenites sp.
- ''?Antevsia sp.''
Insects
- Bandelnielsenia chilena
- Ischichucasyne santajuanaensis
- ''Ademosyne sp.''
Branchiopoda
- Polygrapta troncosoi
- ''Menucoestheria terneraensis''
Bibliogahy
Category:Triassic [System of South America]
Category:Late Triassic South America
Category:Carnian Stage
Category:Triassic Chile
Category:Sandstone formations
Category:Siltstone formations
Category:Conglomerate formations of Chile
Category:Alluvial deposits
Category:Fluvial deposits
Category:Lacustrine deposits
Category:Paleontology in Chile
Category:Geology of Biobío Region