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Information About

La Amarga Formation




The type locality is La Amarga Arroyo and China Muerta Hill (Musacchio, 1970). The La Amarga Formation Unconformably overlies the Marine Agrio Formation of the Mendoza Group . It is in turn overlain by the Lohan Cura Formation , separated by another unconformity.


AGE


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''' through early Aptian

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COMPOSITION


There are three Members within the La Amarga Formation.

The oldest is the Puesto Antigual Member, which is approximately 28.9 Meter s thick and consists mainly of Sandstone deposited in the channels of a Braided River system. Paleosol s, or soil deposits, are well-developed.

The Bañados de Caichigüe Member is the next highest, approximately 20.9 meters thick. Alternating limestones, shales, and siltstones make up this member, indicating a Lacustrine ( Lake ) environment.

Youngest and thickest is the Piedra Parada Member, approximately 109.4 meters thick in some sections. This member consists of alternating sandstones and siltstones from an ancient Alluvial Plain , with some Swamp and paleosol deposits.


PALEONTOLOGY


Most of the Tetrapod Fossil s found in the La Amarga come from the Puesto Antigual Member, including:



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.

  • Musacchio, E. 1970. Ostrácodos de la superfamilias Cytheraceae y Darwinulaceae de la Formación La Amarga (Cretácico inferior), provincia del Neuquén, Argentina. ''Ameghiniana''. 7: 301-318.