Santo Domingo Formation () is a mainly marine

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

sediment Sediment is a solid material that is transported to a new location where it is deposited. It occurs naturally and, through the processes of weathering and erosion, is broken down and subsequently sediment transport, transported by the action of ...

ary formation located in south–central Chile.Encinas et al., 2008 The formation was defined by R. Martínez Pardo and

Mario Pino Mario G. Pino (born September 8, 1961) is a retired American jockey who competed in thoroughbred horse racing. Raised on a farm, he began his riding career in 1978 at Delaware Park in Wilmington. Over the years, he has chosen to be based at race ...

in 1979 and named after the roadcut locality they studied about southeast of

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 ...

. Sediments of the formation accumulated in Valdivia and Osorno–Llanquihue Basin.Elgueta ''et al.''., 2000, p.10 The formations overlie a basement consisting of

metamorphic 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, causi ...

and

igneous rock Igneous rock ( ), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rocks are formed through the cooling and solidification of magma or lava. The magma can be derived from partial ...

s, the

Bahía Mansa Metamorphic Complex The Bahía Mansa Metamorphic Complex (Spanish: ''Complejo Metamórfico Bahía Mansa'', CMBM), also known as the Western Series, is a group of geologic formations in the Chilean Coast Range in southern Chile that have been transformed by heat and ...

and

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

granitoid A granitoid is a broad term referring to a diverse group of coarse-grained igneous rocks that are widely distributed across the globe, covering a significant portion of the Earth's exposed surface and constituting a large part of the continental ...

s, respectively. In parts, it further overlies the coal–bearing Pupunahue–Catamutún Formation. The

sedimentary facies In geology, a facies ( , ; same pronunciation and spelling in the plural) is a body of rock with distinctive characteristics. The characteristics can be any observable attribute of rocks (such as their overall appearance, composition, or con ...

of the Santo Domingo Formation are composed of

sandstone Sandstone is a Clastic rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains, Cementation (geology), cemented together by another mineral. Sand ...

siltstone Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility. Although its permeabil ...

, 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.Blatt, H., and R.J. Tracy, 1996, ''Petrology.'' New York, New York, ...

with smaller amounts of conglomerate.Elgueta ''et al.''., 2000, p.16 The formation underlies

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS), as well as the current and most recent of the twelve periods of the ...

sediments.

Fossil content

Some of the

trace fossil A trace fossil, also called an ichnofossil (; ), is a fossil record of biological activity by lifeforms, but not the preserved remains of the organism itself. Trace fossils contrast with body fossils, which are the fossilized remains of part ...

s that can be found in the Santo Domingo Formation are '' Zoophycos'' isp., ''

Chondrites A chondrite is a stony (non-metallic) meteorite that has not been modified by either melting or planetary differentiation, differentiation of the parent body. They are formed when various types of dust and small grains in the early Solar Syste ...

'' isp., '' Phycoshiphon'' isp., ''

Ophiomorpha ''Ophiomorpha'' is an ichnotaxon, usually interpreted as a burrow of an organism (specifically a crustacean) living in the near-shore environment. The burrow lining is more or less smooth on the inside, and densely to strongly mammalated or nod ...

'' isp. ''

Thalassinoides ''Thalassinoides'' is an ichnogenus of trace fossil (fossil records of lifeforms' movement, rather than of the lifeforms themselves) used to refer to "dichotomously or T-branched boxworks, mazes and shafts, unlined and unornamented". Facies of ' ...

'' isp., ''

Asterosoma ''Asterosoma'' is an ichnogenus of trace fossils typically found in marine sedimentary rocks. These trace fossils are recognized by their characteristic radiating burrow systems, which often resemble a star-like pattern, hence the name ''Asterosom ...

'' isp., and '' Terebellina'' isp.Encinas et al., 2012 The

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from the Ancient Greek word (), meaning "the depths". ...

foraminifera Foraminifera ( ; Latin for "hole bearers"; informally called "forams") are unicellular organism, single-celled organisms, members of a phylum or class (biology), class of Rhizarian protists characterized by streaming granular Ectoplasm (cell bio ...

found in the Santo Domingo Formation are broadly similar to those found in other Chilean sedimentary formations of the Neogene, like the

Navidad Formation Navidad Formation () is a marine Neogene sedimentary geologic formation, formation located in Central Chile. The formation is known for its diverse and abundant fossil record and is considered the reference unit for the marine Neogene in Chile. Or ...

Central Chile Central Chile (''Zona central'') is one of the five natural regions into which CORFO divided continental Chile in 1950. It is home to a majority of the Chilean population and includes the three largest metropolitan areas—Santiago, Valparaí ...

Ranquil Formation The Ranquil Formation () is a Miocene and Pliocene sedimentary geologic formation, formation located in Arauco Province in Zona Sur, south–central Chile, including outcrops in Mocha Island. The formation has its greatest thicknesses in the south ...

Arauco Province Arauco Province () is one of three provinces of the Chilean region of Bío Bío. It spans a coastal area of just south of the mouth of the Biobío River, the traditional demarcation between the nation's major natural regions, Zona Central and ...

, and Lacui Formation of

Chiloé Island Chiloé Island (, , ), also known as Greater Island of Chiloé (''Isla Grande de Chiloé''), is the largest island of the Chiloé Archipelago off the west coast of Chile, in the Pacific Ocean. The island is located in southern Chile, in the Los L ...

. Finger, 2013, p.374 The most common formaineral species of the Santo Domingo Formation are '' Hansenisca altiformis'', '' Rectuvigerina transversa,'' and '' Sphaeroidina bulloides''.Finger, 2013, p.367

References

Bibliography

* * * * {{Geology of Chile Geologic formations of Chile Miocene Series of South America Neogene Chile Sandstone formations Siltstone formations Mudstone formations of Chile Shallow marine deposits Fossiliferous stratigraphic units of South America Paleontology in Chile Geology of Los Ríos Region Geology of Los Lagos Region

Fossil content

See also

References

Bibliography