Los Colorados Formation

Los Colorados Formation
Stratigraphic range: Norian
~227–213 Ma
Los Colorados massif, La Rioja Province, Argentina
TypeGeological formation
Unit ofAgua de la Peña Group
UnderliesCerro Rajado Formation
OverliesIschigualasto Formation
Thickness600 m (2,000 ft)
Lithology
PrimarySandstone, siltstone, mudstone
OtherConglomerate, gypsum
Location
Coordinates29°48′S 67°54′W / 29.8°S 67.9°W / -29.8; -67.9
Approximate paleocoordinates38°54′S 31°24′W / 38.9°S 31.4°W / -38.9; -31.4
RegionSan Juan Province
La Rioja Province
CountryArgentina
ExtentIschigualasto-Villa Unión Basin
Type section
Named forLos Colorados Massif
Los Colorados Formation is located in Argentina
Los Colorados Formation
Los Colorados Formation (Argentina)

The Los Colorados Formation is a sedimentary rock formation of the Ischigualasto-Villa Unión Basin, found in the provinces of San Juan and La Rioja in Argentina. The formation dates back to the Norian age of the Late Triassic.

The up to 600 metres (2,000 ft) thick formation comprises sandstones, siltstones, mudstones and conglomerates with gypsum layers deposited in a fluvial to lacustrine environment. The formation is the uppermost stratigraphic unit of the Agua de la Peña Group, overlying the Lagerstätte of the Ischigualasto Formation. Los Colorados Formation is partly covered by the Cretaceous Cerro Rajado Formation, separated by an unconformity.

The formation is known for its fossils of early dinosaurs, including the coelophysoid Zupaysaurus and the "prosauropods" Coloradisaurus, Lessemsaurus, and Riojasaurus.[1] Magnetostratigraphic analysis suggests that the Los Colorados Formation was deposited between 227 and 213 million years ago.[2]

  1. ^ Weishampel et al., 2004, pp.527-528
  2. ^ Kent et al, 2014, p.7959