Its strata date back to the Early Maastrichtian, and is a unit of the Salta Group.

The fine-grained bioturbated sandstones of the formation were deposited in a fluvial to lacustrine coastal plain environment.

[1] According to Frankfurt and Chiappe (1999), the Lecho Formation is composed of reddish sandstones.

The Lecho is part of the Upper/Late Cretaceous Balbuena Subgroup (Salta Group), which is a near-border stratigraphic unit of the Andean sedimentary basin.

Fossils from this formation include the titanosaur Saltasaurus along with a variety of avian and non-avian theropods.