Estratos de Pupunahue is the name given to the sedimentary strata of Oligocene-Miocene age that crop out in Pupunahue and

Mulpún Mulpún is a coal mine and locality in Los Ríos Region, Chile. Mulpún lies in the commune of Máfil a few kilometers to the west of the Chile Route 5 and north of the Calle-Calle and San Pedro River. History The mine was exploited during parts ...

near

Valdivia Valdivia (; Mapuche: Ainil) is a city and commune in southern Chile, administered by the Municipality of Valdivia. The city is named after its founder Pedro de Valdivia and is located at the confluence of the Calle-Calle, Valdivia, and Cau-Cau R ...

Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...

. Outside this locality Estratos de Pupunahue extends below the surface over a larger area. The thickness of the strata varies from a few meters to 530 meters. The strata were initially described by

Henning Illies Jürgen Henning Illies (14 March 1924 – 2 August 1982) was a German geologist, an expert in taphrogenesis (rift formation). Apart from his work on rifts, including the Rhine Rift Valley, he is known for his contributions to Chilean geology. ...

. The strata are made up of conglomerate,

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) ...

and

mudstone Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from '' shale'' by its lack of fissility (parallel layering).Blatt, H., and R.J. Tracy, 1996, ''Petrology. ...

(

Chilean Spanish Chilean Spanish ( es, español chileno) is any of several varieties of the Spanish language spoken in most of Chile. Chilean Spanish dialects have distinctive pronunciation, grammar, vocabulary, and slang usages that differ from those of Stand ...

: ''fangolita''). The clast of the conglomerates are made up of

metamorphic rock Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causin ...

and the disposition of the conglomerates varies from clast-supported to matrix-supported. The sandstone and mudstone contain layers of

lignite coal Lignite, often referred to as brown coal, is a soft, brown, combustible, sedimentary rock formed from naturally compressed peat. It has a carbon content around 25–35%, and is considered the lowest rank of coal due to its relatively low heat ...

that exceed 30 cm in thickness.

Coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal is formed when dea ...

layers found in the Estratos de Pupunahue have been exploited in the mines of

Catamutún Catamutún is a coal mine and locality in Los Ríos Region, Chile.Pupunahue and

("Mulpun Beds"). The strata are very similar to the Cheuquemó Formation found further north, with the sole difference that the fossil assemblage in both seems to indicate different ages. While Cheuquemó Formation is possibly about 14 million years old (Miocene), Estratos de Pupunahue are 35–25 million years old.

See also