The Colônia crater is a recently confirmed impact crater located in the municipality of

São Paulo São Paulo (, ; Portuguese for 'Saint Paul') is the most populous city in Brazil, and is the capital of the state of São Paulo, the most populous and wealthiest Brazilian state, located in the country's Southeast Region. Listed by the GaWC a ...

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

. It is a round bowl-shaped depression, without any obvious central bulge, with a diameter of about , bounded by a circular ring of hills about high relative to the inner depression. Its approximate location is 23°52′15″ South and 46°42′30″ West, above sea level. The name comes from the town district of Colônia located just north of the feature.

Geology and ecology

Some geologists believe that the feature was created by the impact of a

meteorite A meteorite is a solid piece of debris from an object, such as a comet, asteroid, or meteoroid, that originates in outer space and survives its passage through the atmosphere to reach the surface of a planet or Natural satellite, moon. When the ...

with a diameter of about . It was formed between 1 millionCláudio Riccomini, Álvaro Crósta, Marie-Pierre Ledru, Renato Luis Prado, Bruno Turq, Lucy Sant'Anna, José Ferrari, and Wolf Reimold (2011), ''The Colônia structure, São Paulo, Brazil''. Meteoritic & Planetary Science, to appear and 20 million years ago, in crystalline

basement rock In geology, basement and crystalline basement are crystalline rocks lying above the mantle and beneath all other rocks and sediments. They are sometimes exposed at the surface, but often they are buried under miles of rock and sediment. The baseme ...

s 600 to 700 millions of years old. The Earth Impact Database gives a range of 36 to 5 Ma. In any case, it would be one of the youngest South American impact craters known. It is partially filled by

peat Peat (), also known as turf (), is an accumulation of partially decayed vegetation or organic matter. It is unique to natural areas called peatlands, bogs, mires, moors, or muskegs. The peatland ecosystem covers and is the most efficien ...

with maximum depth of , which provides a precious record of ancient environment. The upper , in particular, have provided a detailed climate and ecological record of the last 130,000 years; the complete record may stretch back to 2.5 million years ago. Data from seismic and other surveys indicate that below the sediment there are about of fragmented rock deposits, and another 50 m of shocked or deformed basement rock. Sediment analysis indicate that until 18,000 years ago a lake occupied the central part of the crater, which has become a swamp.Paulo Gomes Varella (2009
A CRATERA DE COLÔNIA
(in Portuguese). The crater is drained towards the east by the Vargem Grande creek into the adjacent

Billings Reservoir __NOTOC__ The Billings Reservoir (locally known as Represa Billings) is the largest reservoir in São Paulo, Brazil, covering a total of 127 km2. It is named after Asa White Kenney Billings, the American hydroelectric engineer who was instru ...

. The tentative identification as an impact crater is based mainly on

geomorphology Geomorphology (from Ancient Greek: , ', "earth"; , ', "form"; and , ', "study") is the scientific study of the origin and evolution of topographic and bathymetric features created by physical, chemical or biological processes operating at or n ...

, faulting pattern, and on the exclusion of other possible formation mechanisms. In particular, there are no carbonate rocks that could produce to

karst Karst is a topography formed from the dissolution of soluble rocks such as limestone, dolomite, and gypsum. It is characterized by underground drainage systems with sinkholes and caves. It has also been documented for more weathering-resistant ro ...

sinkhole A sinkhole is a depression or hole in the ground caused by some form of collapse of the surface layer. The term is sometimes used to refer to doline, enclosed depressions that are locally also known as ''vrtače'' and shakeholes, and to openi ...

s. As of 2011 there were no reports of definite evidence, such as shatter cones or

shocked quartz Shocked quartz is a form of quartz that has a microscopic structure that is different from normal quartz. Under intense pressure (but limited temperature), the crystalline structure of quartz is deformed along planes inside the crystal. These pla ...

. To find such evidence one would have to drill through the sediment fill.

Urbanization and legal status

The Colônia crater is located in the suburban Parelheiros region of the sprawling São Paulo metropolitan area, about from the city's center. Besides the central swamp, the crater encloses remains of the native

Atlantic rainforest The Atlantic Forest ( pt, Mata Atlântica) is a South American forest that extends along the Atlantic coast of Brazil from Rio Grande do Norte state in the northeast to Rio Grande do Sul state in the south and inland as far as Paraguay and the ...

. Starting in 1989, the northern part of the crater has been gradually occupied by irregular housing that comprise the

Vargem Grande Vargem Grande is a city in Maranhão state. Its population is 57,168 (2020) and its total area is 1,958 km2. References

Municipalities in Maranhão {{Maranhão-geo-stub ...

neighborhood, now home to 35,000 to 40,000 people. To prevent further degradation, the crater has been declared a protected natural landmark, registered in 1995 by the

CONDEPHAAT The Council for the Defense of Historical, Archaeological, Artistic and Tourist Heritage ( pt, Conselho de Defesa do Patrimônio Histórico, Arqueológico, Artístico e Turístico), or CONDEPHAAT, protects, values and communicates information abou ...

. Its southern part was incorporated to the Capivari Monos Municipal Parkland in 1996.

Geology and ecology

Urbanization and legal status

See also

References

Further reading