Colônia crater
{{Short description|Impact crater in São Paulo, Brazil}}
{{Infobox terrestrial impact site
| name = Colônia crater
| other_name =
| photo = Colônia crater LC08 L1TP 219076 20170405 20170414 01 T1.jpg
| photo_size =
| photo_alt =
| photo_caption = 2017 Landsat image of Colônia crater
| map = Brazil
| map_alt =
| map_caption = Location of the crater in Brazil
| map_size =
| location =
| label =
| label_position =
| coordinates = {{Coord|23|52|15|S|46|42|30|W|region:BR-SP_type:landmark|display=inline,title}}
| coordinates_ref =
| confidence = Confirmed
| diameter = {{convert|3.6|km|mi|abbr=on}}
| depth =
| rise =
| imp_size =
| age = 5 to 36 Ma
Neogene
| exposed = Yes
| drilled = Yes
| bolide =
| translation =
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| topo =
| access =
| country = Brazil
| state = São Paulo
| province =
| district = Parelheiros
| municipality = São Paulo
}}
The Colônia crater is a recently confirmed impact crater located in the municipality of São Paulo, Brazil.{{Cite Earth Impact DB |name=Colonia |access-date=2020-02-13}} It is a round bowl-shaped depression, without any obvious central bulge, with a diameter of about {{convert|3.6|km|mi}}, bounded by a circular ring of hills about {{convert|125|m|ft}} high relative to the inner depression. Its approximate location is {{Coord|23|52|S|46|42|W|display=inline}}, {{convert|770|m|ft}} 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 with a diameter of about {{convert|200|m|ft}}. 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 rocks 600 to 700 million 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 with a maximum depth of {{convert|275|m|ft}}, which provides a precious record of the ancient environment. The upper {{convert|8|m|ft}}, 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 {{convert|50|to|65|m|ft}} 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) [http://www.ceuaustral.pro.br/colonia.htm A CRATERA DE COLÔNIA] (in Portuguese). The crater is drained towards the east by the Vargem Grande creek into the adjacent Billings Reservoir.
The tentative identification as an impact crater is based mainly on geomorphology, faulting patterns, and on the exclusion of other possible formation mechanisms. In particular, there are no carbonate rocks that could produce karstic sinkholes. As of 2011 there were no reports of definite evidence, such as shatter cones or shocked quartz. 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 {{convert|35|km|mi}} from the city's center. Besides the central swamp, the crater encloses remains of the native Atlantic rainforest. Starting in 1989, the northern part of the crater has been gradually occupied by irregular housing that comprise the Vargem Grande 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. Its southern part was incorporated to the Capivari Monos Municipal Parkland in 1996.
See also
{{Portal|Brazil|Geology}}
References
{{reflist}}
Further reading
- C. Riccomini, F.A.P.S. Neves, B. Turcq (1992), Astroblema de Colônia (São Paulo, Brasil): Estágio atual de conhecimento. 37º Congresso Brasileiro de Geologia, Sociedade Brasileira de Geologia.
{{Impact cratering on Earth}}
{{DEFAULTSORT:Colonia crater}}
Category:Impact craters of Brazil
Category:Geography of São Paulo