Mapping regional geodiversity in Brazil and Portugal

Abstract

A methodology meant to be used in the quantitative assessment and mapping of geodiversity was defined for regional scale, following the initial proposal of Pereira et al. (2012). The method was tested in the Xingu Basin, Amazon, Brazil (about 510,000 km2), Paraná State, Brazil (about 200,000 km2), and Portugal mainland (about 89,000 km2). It is a GIS method intended to assess all features of geodiversity and to avoid overrating any particular one, such as lithology or relief, which is a com- mon weakness in other methods. The procedure consists on the overlay of a grid over different types of maps at scales between 1:250 000 and 1:1 000 000. The number of geological units (stratigraphical and lithological) that occurs in each grid cell of the geological map is counted, producing a map of geological indexes. The geomorphological index map results from the sum of the relief and hydrographical indexes obtained from the geomorphological units map. Palaeontological and pedological index maps are obtained from counting palaeontological units and soil units, respectively. The singular occurrences index map is based on the number of occurrences such as precious stones and metals, energy and industrial minerals, mineral waters and springs. The final Geodiversity Map results from the combination of those five partial indexes. The Geodiversity Map is a GIS automatically generated map, which allows an easy interpretation by non specialists. The map can be used as a tool in land-use planning, particularly for the identification of priority areas for conservation, and for the use and management of natural resources.