Geological Map of South America (2019)

Geological map of South America

The new edition of the Geological Map of South America (GMSA), at a scale of 1:5 M, has been elaborated by the South America Subcommission of the Commission of the Geological Map of the World (CGMW). It was approved by the General Assembly of the CGMW held in Oslo, Norway, during the 33rd International Geological Congress.

This third version was prepared with the cooperation of the Association of Ibero-American Geological and Mining Surveys (ASGMI), the Geological Surveys of Argentina, Brazil, Chile, Colombia, Ecuador, Peru and Uruguay, as well as several additional universities and research institutes mentioned in the contributors' information.

The Sub-Committee on Geological map of South America adopted a methodology integrating the geological information of each country in the following way. First, a new code was generated for each chronostratigraphic unit according to the proposed legend, using digital layers provided by the geological surveys of each country.

Secondly, the symbology and colours were created with patterns representative of the rock types and colours corresponding to the ages.

Finally, a map with coded units was prepared at a scale of 1:5 M.

In order to generalise and link the units by hand, the GMSA was printed at a scale of 1/3 M with the new coding. The GMSA was then digitised and georeferenced to generalise the geological units, faults and folds at a scale of 1:5M.

Having done this, and despite the small scale of the map, the chronostratigraphic units, faults and folds on the map were adjusted using shaded relief imagery (NASA STRM) to improve the match between relief and mapped geological units.

Finally, the geology between countries has been harmonised. It should be noted that the updating of the GMSA has been carried out by consulting internationally indexed published articles.

The Geological map of South America is based on a polyconic projection (latitude × longitude), centred on the meridian -59°, datum WGS - 1984.

Offshore data were extracted from the 1/5.9M scale Tectonic Map of South America (Cordani et al., 2016); the GEBCO 08 Grid Seafloor Topography, version 20100927; and the crustal age grid: NCEI / NOAA.

For more information on the GMSA and the digital version of the card, please click here.