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Domo de Araguainha Impact Structure

BRAZIL

View of the central uplift of Araguainha Dome. The hills comprise Furnas sandstone and impact breccia. The scene in the background is close to 3 km across (Photo: J. Sanchez).

Geological Period

Permian-Triassic boundary

Main geological interest

Impact structures and extraterrestrial rocks
Stratigraphy and sedimentology

Location

States of Mato Grosso and Goiás, central Brazil.
16°48’00.0″S, 52°59’00.0″W

View of the central uplift of Araguainha Dome. The hills comprise Furnas sandstone and impact breccia. The scene in the background is close to 3 km across (Photo: J. Sanchez).

THE LARGEST (~40 KM) AND BEST EXPOSED IMPACT STRUCTURE IN SOUTH AMERICA WITH EXAMPLES OF IMPACTITES AND SHOCK DEFORMATION FEATURES.

The structure boasts spectacular scenery and is easily accessible. A diversity of impact lithologies, such as polymictic impact breccia and impact melt rocks, together with abundant shock deformation features such as shatter cones and a variety of microscopic shock deformation features, make the Araguainha Dome a fantastic natural laboratory to understand impact cratering and planetary processes. It has even been suggested that this impact could have been involved, directly or indirectly, with the major mass extinctions at the Permian-Triassic boundary. Textbook examples of impactites and shock deformation features make Araguainha an ideal location for developing geotourism, geoheritage and geoconservation-related, as well as educational, activities.

Prominent shatter cones in phyllites of the crystalline basement. Pen for scale is 14 cm long (Photo: A. P. Crósta).

  • Geological description

The Domo de Araguainha (Araguainha Dome) exhibits a large diversity of rock types and impact features exposed in its >1.3 thousand km2 area, including Neoproterozoic and Paleozoic crystalline rocks at the center of the structure that are surrounded by Silurian to Permian sedimentary strata of the intracratonic Paraná Basin. The impact structure is cut by the Araguaia River that drains into the Amazon River basin. The structure exhibits an annular, concentric structure with a central uplift where the Neoproterozoic to Cambrian crystalline basement is well exposed. The central uplift is surrounded by sedimentary sequences of the Paraná Basin including, from the base to the top, the Rio Ivaí (Silurian), Paraná (Devonian), Itararé (Carboniferous), and Passa Dois (Permian) groups. The sedimentary strata are arranged in a bull´s eye pattern around the central crystalline core, forming a formidable geological scenario. Impactites, namely polymict impact breccia and various types of impact melt rock, occur abundantly in the central portion of the structure.

  • Scientific research and tradition

Brazilian and foreign scientific investigations have been conducted at Araguainha since the 1960s, and results have been widely published. Excursions have been conducted as part of international conferences, such as an International Geological Congress, Annual Meeting of the Meteoritical Society, Large Meteorite Impacts and Planetary Evolution VI conference.

Geological map and cross section for the Araguainha Dome (CPRM/Brazilian Geological Survey); inset: location of the structure in the Paraná Basin (dark grey).

  • Reference

Crósta, A.P. et al. (2019) ‘Impact cratering: The South American record – Part 1’, Geochemistry, 79(1), pp. 1–61. Available at: https://doi.org/10.1016/j.chemer.2018.06.001.

Crósta, A.P., Gaspar, J.C. and Candia, M. (1981) ‘Feições de metamorfismo de impacto no Domo de Araguainha’, Revista Brasileira de Geociências, 11, pp. 139–146. Available at: https://doi.org/10.5327/RBG.V11I3.219.

Engelhardt, W.V., Matthäi, S.K. and Walzebuck, J. (1992) ‘Araguainha impact crater, Brazil. I. The interior part of the uplift’, Meteoritics, 27(4), pp. 442–457. Available at: https://doi.org/10.1111/j.1945-5100.1992.tb00226.x.

Hauser, N. et al. (2019) ‘Linking shock textures revealed by BSE, CL, and EBSD with U-Pb data (LA-ICP-MS and SIMS) from zircon from the Araguainha impact structure, Brazil’, Meteoritics & Planetary Science, 54(10), pp. 2286–2311. Available at: https://doi.org/10.1111/maps.13371.

Lana, C. et al. (2008) ‘Structural evolution of the 40 km wide Araguainha impact structure, central Brazil’, Meteoritics & Planetary Science, 43(4), pp. 701–716. Available at: https://doi.org/10.1111/j.1945-5100.2008.tb00679.x.

Tohver, E. et al. (2013) ‘Shaking a methane fizz: Seismicity from the Araguainha impact event and the Permian–Triassic global carbon isotope record’, Palaeogeography, Palaeoclimatology, Palaeoecology, 387, pp. 66–75. Available at: https://doi.org/10.1016/j.palaeo.2013.07.010.

  • Author(s)

Alvaro P. Crósta
State University of Campinas, Brazil

Natalia Hauser
University of Brasília, Brazil

Uwe Reimold
University of Brasília, Brazil

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