Confirmed meteoritic impact structures and potential sites in West Africa

Over 210 impact structures have been confirmed on Earth. However, this figure represents only a small portion of the true history of collisions between Earth and extraterrestrial objects. Much of the terrestrial impact record has been lost due to tectonic activity, volcanism, erosion, and burial by sediments. Furthermore, the current distribution of recognized impact structures across the continents is highly uneven. Africa, for instance, has only 20 confirmed structures—about 10 % of the global total—despite making up roughly a quarter of the non-glaciated continental land area and hosting extensive Archean and Paleoproterozoic terranes.

The deficit is even starker in West Africa, where just three impact structures have been confirmed across a region spanning over 5 million km²—about one-fifth the size of the African continent, 80 % of which consists of ancient geological terranes. West Africa is defined here as the region including the 16 following countries:  Benin, Burkina Faso, Cape Verde, The Gambia, Ghana, Guinea, Guinea-Bissau, Ivory Coast, Liberia, Mali, Mauritania, Niger, Nigeria, Senegal, Sierra Leone, and Togo (which corresponds to the United Nations (UN) and Economic Community of West African States (ECOWAS) definitions).

Numerous potential impact sites in West Africa have been proposed, often based on remote sensing. However, several factors hinder progress in verifying these sites: limited accessibility, security challenges, insufficient research funding, and a limited number of local geologists with some expertise in impact science. Here, we have compiled the current knowledge on confirmed, rejected, and potential impact structures in West Africa, which has just been presented in a review paper [1]. This compilation serves as a gateway to the literature, and to encourage local geologists to conduct field investigations. The compilation takes also advantage of recent data, such as the FABDEM, a public topographic data platform of unprecedented quality [2]. The topographic information has been extracted for each site and is provided on a public data repository [3]. The compilation also highlights the potential links between impact structures and economically valuable mineral deposits, underscoring their relevance to exploration geologists and mining companies operating in the region.

In this review of confirmed, possible, and unlikely impact structures in West Africa, we have evaluated 16 potential sites in detail (Fig. 1). Among them, we recommend prioritizing future research—such as field investigations, geophysical surveys, sampling, and petrographic analysis—on the most promising candidates: Anefis, El Mrayer or Mejaouda, Tafassasset, Temimichat Ghallaman, Terhazza, and Velingara.

Fig. 1 - Map of the locations of confirmed impact structures (green), potential impact structures (yellow), and discarded (red) structures in West Africa, superposed onto regional climate/vegetation zones and rainfall isolines, in cylindrical map projection) [1].

West Africa's impact structure record is undoubtedly incomplete, indicating considerable potential for new discoveries across this region. Despite obstacles listed above, future expeditions can still be planned, with priorities refined through ongoing advancements in remote sensing and analytical techniques. Notably, one of the earliest confirmed African impact structures, Aouelloul, was initially identified through aerial imagery [4]. In more recent efforts, systematic searches for circular features have been conducted in Morocco using modern satellite imagery [5], whereas surveys in Mauritania have combined satellite imagery with topographic data in an innovative approach [6]. Citizen science can also play a meaningful role in advancing impact structure research. The Vigie-Cratère program (https://vigie-cratere.org), active across multiple countries and continents, provides a platform for the public to help identify circular structures using shaded relief and satellite imagery, or to submit information (pictures, observations) that help to prioritize future field expeditions.

Bibliographic references

[1] Niang, C.A.B., Baratoux, D., Rochette, P., Quesnel, Y., Reimold, W.U., 2025. The impact record of West Africa: Confirmed impact structures and potential impact sites. Journal of African Earth Sciences 228, 105627. https://doi.org/10.1016/j.jafrearsci.2025.105627

[2] Hawker, L., Uhe, P., Paulo, L., Sosa, J., Savage, J., Sampson, C., Neal, J., 2022. A 30 m global map of elevation with forests and buildings removed. Environ. Res. Lett. 17, https://doi.org/10.1088/1748-9326/ac4d4f

[3] Niang, C.A.B., 2025. FABDEM data of confirmed and potential impact structures in West Africa. https://doi.org/10.5281/zenodo.14630132.

[4] Ould Mohamed Navee, E., Chennaoui Aoudjehane, H., Baratoux, D., Ferrière, L., Ould Sabar, M.S., Si Mhamdi, H., 2024a. Aouelloul impact crater, Mauritania: new structural, lithological, and petrographic data. J. Afr. Earth Sci., 105210 https://doi.org/j.jafrearsci.2024.105210

[5] Chaabout, S., Chennaoui Aoudjehane, H., Reimold, W.U., Baratoux, D., Youbi, N., 2015. Prospecting for possible impact structures in Morocco. J. Afr. Earth Sci. 112, 339–352. https://doi.org/10.1016/j.jafrearsci.2015.08.002.

[6] Ould Mohamed Navee, E., Baratoux, D., Chennaoui Aoudjehane, H., Si Mhamdi, H., Raji, M., 2024b. Systematic search of circular structures using satellite imagery to identify potential new impact structures in Mauritania. J. Afr. Earth Sci. 216, 105303. https://doi.org/10.1016/j.jafrearsci.2024.105303.