Geodiversity Index Map of Rio Grande do Norte State, Northeast Brazil: Cartography and Quantitative Assessment

The values of geodiversity, defined through different qualitative and/or quantitative methods, represent a fundamental asset for the development of geoconservation actions. Quantitative methods can be considered those of less subjectivity since their dependence on the evaluator and its scientific knowledge is restricted. In turn, aiming to clearly expose the achieved results, this work used geoprocessing tools, as it has been used in several studies of geodiversity index in Brazil. Rio Grande do Norte, a state located in the extreme northeast and one of the smallest of the country, still does not have an assessment for its entire territory, despite being geologically diverse, with rocks dated back from the Archean until the Holocene. Thus, the objective of this work is to fill this gap in the studies of Brazilian geodiversity. For this, we used the evaluation methodology based on the grid overlay, with 5.5 × 5.5 km mesh, on the available cartographic bases: lithology, mineral occurrences, geomorphology, pedology, and hydrography. The thematic subindexes were added, which resulted in the geodiversity index map for the entire state. It was classified into five classes: very low, low, medium, high, and very high. It was verified that most of the state is in low areas in the geodiversity index and that the high and very high areas are concentrated in specific portions, mainly in three distinct regions: Eastern Seridó, Center-East, and Eastern Coast. It was observed that Rio Grande do Norte state is endowed with high potential regions of geodiversity.