Los Molles Formation

Los Molles Formation Stratigraphic range: Pliensbachian-Callovian ~185–165 Ma PreЄ Є O S D C P T J K Pg N
Type	Geological formation
Unit of	Cuyo Group
Underlies	Niyeu–Lajas Formation
Overlies	Lajoa Formation
Lithology
Primary	Organic shale
Other	Lime-mudstone
Location
Coordinates	39°10′18″S 69°39′35″W / 39.17167°S 69.65972°W / -39.17167; -69.65972Coordinates: 39°10′18″S 69°39′35″W / 39.17167°S 69.65972°W / -39.17167; -69.65972
Region	Neuquén Province
Country	Argentina
Type section
Country	Argentina

The Los Molles Formation is a geologic formation of Early Jurassic age, located at northern and central part of Neuquén Basin at Mendoza Shelf in Argentina. It is overlain by the Niyeu–Lajas Formation.

It is the second largest oil and gas formation in the Neuquén Basin after Vaca Muerta Formation. The Los Molles Formation is estimated to have 275 trillion cubic feet (7.8×10^¹² m³) of technically recoverable shale gas and 3.7 billion barrels (590,000,000 m³) of technically recoverable oil. In July 2015, the Buenos Aires Herald indicated that Pan American Energy and YPF planned to drill 46 shale gas wells in the Grupo Cuyo formation (Los Molles) over the next four years in their Lindero Atravesado drilling block, at an estimated cost of US$590 million.

In several outcrops, the Los Molles formation has been the site of paleontological discoveries: the ichthyosaurs Chacaicosaurus and Mollesaurus, and, in 2017, an ornithischian, Isaberrysaura, discovered with fossilised contents of the gut.