Lohan Cura Formation
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The Lohan Cura Formation is a geologic formation with outcrops in the Argentine provinces of Río Negro, Neuquén, and Mendoza. It is the second oldest Cretaceous terrestrial formation in the Neuquén Basin.
The Lohan Cura Formation unconformably overlies the terrestrial La Amarga Formation. In some places it also overlies the older marine Agrio and Bajada Colorada Formations of the Mendoza Group through the same unconformity. It is in turn overlain by the Candeleros Formation of the Neuquén Group, separated by another unconformity. The Lohan Cura correlates with the Rayoso Formation in some areas.
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[edit] Age
Era: Mesozoic
Period: Early Cretaceous
Faunal stage: late Aptian through Albian
Absolute Age: ~117 to ~100 mya
[edit] Composition
The Lohan Cura Formation contains two members of roughly equal thickness.
The lower (and therefore older) of the two is the Puesto Quiroga Member, approximately 85 meters thick. The lowest sediments in this formation are conglomerates, overlain by sandstones and siltstones. The upper two-thirds of the member consists mainly of shales.
The Cullín Grande Member is the upper member within the formation, about 92 meters thick, which contains numerous stream channels in sandstone. By the top of the column, siltstones and claystones become dominant.
[edit] Paleontology
Numerous tetrapod fossils have been recovered from the Cullín Grande Member of the Lohan Cura, including:
- several turtles (including 2 species of Prochelidella)
- rebbachisaurid sauropods
- possible titanosaurian sauropods (including Agustinia and Ligabuesaurus)
The rebacchisaurid Rayososaurus comes from the correlating Rayoso Formation in this same area.
[edit] References
- Leanza, H.A,, Apesteguia, S., Novas, F.E. & de la Fuente, M.S. 2004. Cretaceous terrestrial beds from the Neuquén Basin (Argentina) and their tetrapod assemblages. Cretaceous Research. 25(1): 61-87.
