| Loreto Formation | |
| Type: | Geological formation |
| Period: | Priabonian |
| Age: | Priabonian (Divisaderan) |
| Prilithology: | Sandstone |
| Otherlithology: | Conglomerate, coal |
| Namedby: | Hoffstetter et al. |
| Year Ts: | 1957 |
| Region: | Magallanes y la Antártica Chilena Region |
| Coordinates: | -53.1°N -71.1°W |
| Paleocoordinates: | -55.3°N -61.4°W |
| Underlies: | not observed |
| Overlies: | Leña Dura Formation |
| Extent: | Magallanes Basin |
Loreto Formation (Spanish; Castilian: Formación Loreto) is a sedimentary formation of Late Eocene age in the southernmost Magallanes Basin. It overlies the Leña Dura Formation and the contact with an overlying formation is not observed.[1] From 2013 to 2020 its coals were mined in Invierno mine, Riesco Island.[2] [3] [4]
The formation contains fossil wood, leaf imprints and palynomorphs.[5] Also fossil fish of Striatolamia macrota and Ischyodus dolloi and indeterminate Spheniscidae fossils have been found in the formation.[6] [7]
The formation crops out in Brunswick Peninsula and Sierra Baguales among other places.[8]