| Riachão Ring | |
|---|---|
 Landsat image of the Riachão Ring (2017) | |
| Impact crater/structure | |
| Confidence | Confirmed |
| Diameter | 4.5 km (2.8 mi) |
| Age | <200 Ma |
| Exposed | Yes |
| Drilled | No |
| Location | |
| Location | Parnaíba Basin |
| Coordinates | 7°43′S 46°39′W / 7.717°S 46.650°W |
| Country | Brazil |
| State | Maranhão |
  Location of the crater in Brazil | |
Riachão Ring is a meteorite impact crater in Brazil. It lies within the Parnaíba Basin. It is 4.5 kilometres (2.8 mi) in diameter and the age is estimated to be less than 200 million years (Jurassic or younger). The crater is exposed at the surface.[1]
The structure was first identified from analysis of orbital photographs acquired during the Apollo–Soyuz Test Project in 1975.[2] A reconnaissance investigation of the structure was reported by J. F. McHone in 1977.[3] The structure of the site (dipping breccia along the rim) supported interpretation of an impact origin, but no shatter cones or shocked quartz were found at the time.
The crater is severely eroded and there is apparently no ejecta remaining. The crater rim rises about 50 m above the surrounding surface, and a central uplift is about 30 m above the annular depression within the rim. Shock deformation has been identified in quartz grains within the central uplift.[4]
Part of 1975 discovery photo (AST-23-1931) of the Riachão Ring, by astronauts of the Apollo–Soyuz Test Project
1978 panoramic camera subframe
References
- ↑ "Riachão Ring". Earth Impact Database. Planetary and Space Science Centre University of New Brunswick Fredericton. Retrieved 2017-10-09.
- ↑ R. S. Dietz and J. F. McHone, 1977, Volcanic Landforms and Astroblemes. In Apollo–Soyuz Test Project Summary Science Report, Volume II, Earth Observations and Photography Edited by Farouk El-Baz and D. M. Warner. Prepared by NASA Lyndon B. Johnson Space Center. NASA Special Publication 412.
- ↑ J. F. McHone, 1977, Riachão Ring, Brazil: A Possible Meteorite Crater Discovered by the Apollo Astronauts. In Apollo–Soyuz Test Project Summary Science Report, Volume II, Earth Observations and Photography Edited by Farouk El-Baz and D. M. Warner. Prepared by NASA Lyndon B. Johnson Space Center. NASA Special Publication 412.
- ↑ THE RIACHÃO RING IMPACT STRUCTURE, NORTHEASTERN BRAZIL: RE-EVALUATION OF ITS STRATIGRAPHY AND EVIDENCE FOR IMPACT, M. V. Maziviero, M. A. R. Vasconcelos, A. M. Góes, A. P. Crósta, and W. U. Reimold. 43rd Lunar and Planetary Science Conference (2012).
