Roca Formation, Argentina
The Roca Formation is a Cretaceous to Paleogene lithostratigraphic unit, located in the Neuquén Basin. It crops out in the Argentinian provinces of Río Negro, Neuquén, La Pampa, and Mendoza. Its deposition is diachronous, beginning during the Maastrichtian in the north of its distribution, and later moving to the south, where its strata reached the Late Danian. It lies transitionally above the Jagüel Formation, and the top of the formation is marked by a regional unconformity due to an Eocene and Oligocene orogenic pulse. These two units belong to the Malargüe Group. The marine sediments of the Jagüel and Roca Formations were deposited during a transgression from the Atlantic Ocean, beginning in the Maastrichtian and ending in the Danian.
Roca Formation in Barda Norte, General Roca, Río Negro
Lime kiln in Barda Norte Locality, General Roca, Río Negro, Argentina
Limestones in Roca Formation, Cantera Cholino, General Roca, Río Negro
The Jagüel Formation is a geological formation, located in Patagonia, Argentina. It underlies the Roca Formation and overlies the Allen Formation. All of these formations belong to the Malargüe Group. Its name was coined by Windhausen in 1914. This unit, defined in the eastern area of the Neuquén Embayment, registers an event of marine flooding that happened during the ages Maastrichtian and Danian. It consists of mudrocks formed between the upper section or "Gypsum" of the Allen Formation, and the base of the first organogenic limestone of the Roca Formation. The Jagüel Formation is particularly important since a vast area of the formation contains the Cretaceous–Paleogene boundary that marks the end of the Mesozoic Era. It also shows evidence of the Cretaceous–Paleogene (K–Pg) extinction event. In this period of time, animal species became extinct, such as non–avian dinosaurs, the last marine reptiles, ammonites, and many groups of microfossils.
Outcrops of Malargüe Group in Cañadón Cholino (General Roca)