The Candeleros Formation (formerly known as the Candeleros Member of the "Río Limay Formation") is a geologic formation that crops out in the Río Negro, Neuquén, and Mendoza provinces of northern Patagonia, Argentina. It is the oldest formation in the Neuquén Group and belongs to the Rio Limay Subgroup. Formerly that subgroup was treated as a formation, and the Candeleros Formation was known as the Candeleros Member.
Description
The type locality of the Candeleros Formation is Candeleros Hill in Neuquén Province, after which the formation was named by Wichmann in 1929. This formation unconformably overlies the Lohan Cura Formation, and it is in turn overlain by the Huincul Formation, also a unit of the Neuquén Group. The sediments of the latter are of lighter greenish and yellow colors and the boundary between the Candeleros and Huincul formations is easily recognizable.
The Candeleros Formation is almost 300 metres (980 ft) thick in some sections. Overall, the formation represents a part of the ancient Kokorkom desert with braided river system, made up mostly of sandstones and conglomerates. There are also isolated sections that represent eolian (wind-blown) deposition, as well as siltstones deposited under swamp conditions. Paleosols (soil deposits) are common in some sections as well.
Fossil content
The Candeleros Formation has a very diverse fossil fauna, including:
In 2021, fossil material of a giant titanosaur sauropod, distinct from Andesaurus and probably exceeding Patagotitan in size, was described from the formation by Otero et al. (2021).
MPCA PV 454, a partial skull without skull roof, basicranium, and squamosals, and from the referred specimens MPCA PV 450, a partial left lower jaw with damaged teeth, and MPCA PV 453, an incomplete skull with a relatively complete right lower jaw missing some teeth.
A small insectivorous mammal that belongs to the Meridiolestida family.
