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The Vichada Structure is a probable
The Vichada Structure is a probable impact structure
An impact structure is a generally circular or craterlike geologic structure of deformed bedrock or sediment produced by impact on a planetary surface, whatever the stage of erosion of the structure. In contrast, an impact crater is the surface e ...
along the Vichada River
The Vichada River (, ) is a blackwater river in Colombia, South America. It flows into the Orinoco River.
The eastward course of the Vichada is offset by an Impact crater, impact structure, called the Vichada Structure. The structure is most li ...
in Colombia
Colombia, officially the Republic of Colombia, is a country primarily located in South America with Insular region of Colombia, insular regions in North America. The Colombian mainland is bordered by the Caribbean Sea to the north, Venezuel ...
(Vichada Department
Vichada Department (, ) is a department of the Republic of Colombia in South America. Vichada is located in the eastern plains of Colombia, in the Orinoquía Region within the Orinoco river basin bordering the Bolivarian Republic of Venezuel ...
), South America
South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...
. It is most likely the largest impact structure in South America.
The structure was discovered in 2004 by Max Rocca, a geologist
A geologist is a scientist who studies the structure, composition, and History of Earth, history of Earth. Geologists incorporate techniques from physics, chemistry, biology, mathematics, and geography to perform research in the Field research, ...
in Buenos Aires, by examining Landsat
The Landsat program is the longest-running enterprise for acquisition of satellite imagery of Earth. It is a joint NASA / USGS program. On 23 July 1972, the Earth Resources Technology Satellite was launched. This was eventually renamed to Lan ...
imagery. He was supported by a grant from the Planetary Society
The Planetary Society is an American internationally-active non-governmental nonprofit organization. It is involved in research, public outreach, and political space advocacy for engineering projects related to astronomy, planetary science, an ...
. The structure consists of a central flat depression surrounded by two concentric rings of hills of approximately 30 and 50 km diameter. The Vichada River anomalously flows around the outer ring of hills. An international team of scientists collected aerial gravity data over the 50 km wide structure and discovered a positive free-air anomaly
In geophysics, the free-air gravity anomaly, often simply called the free-air anomaly, is the measured gravity anomaly after a free-air correction is applied to account for the elevation at which a measurement is made. It does so by adjusting thes ...
at the center of the structure, supporting its interpretation as an impact structure.Hernandez, O., et al., 2009, Geophysical evidence for an impact crater in Vichada, northwestern South America, and its economic potential, Earth Sci. Res. J., Vol. 13, No. 2 (December 2009): 97-107
See also
*List of impact craters in South America
This list includes all List of impact structures on Earth#All craters listed alphabetically, 11 confirmed impact structures in South America as listed in the Earth Impact Database. These features were caused by the collision of large meteorites o ...
* List of possible impact structures on Earth
This list includes potential but unconfirmed structures that are not listed on the Earth Impact Database list of confirmed impact structures. For confirmed impact structures, see List of impact structures on Earth.
List of confirmed and possibl ...
References
{{Impact cratering on Earth Impact craters of Colombia