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 fuchsiiA. rigbyanaBaiera africanaB. furcataCladophlebis mendozaensisDicroidium coriaceumD. crassinervisD. elongatumD. odontopteroidesDictyophyllum fuenzalidaiD. tenuifoliumGleichenites quilacoyensisGontriglossa reineraeHeidiphyllum elongatumKurtziana cacheutensisLinguifolium lilleanumL. steinmanniiPterophyllum santajuanensisRissikia mediaSaportaea dichotomaSphenobaiera africanaSphenopteris cf. polymorphaTaeniopteris sp.Taeniopteris vittataTelemachus elongatusThaumatopteris rothiiTodites chilensiscf. Pseudoctenis fissaCladophlebis sp.Dicroidium sp.Gleichenites sp.
  • ''?Antevsia sp.''

Insects

Bandelnielsenia chilenaIschichucasyne santajuanaensis
  • ''Ademosyne sp.''

Branchiopoda

Polygrapta troncosoi
  • ''Menucoestheria terneraensis''

Bibliogahy

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