Speaker
Description
The 1.07 Ma Bosumtwi impact crater in Ghana is one of the best-preserved large impact structures on Earth. It is the source crater of tektites, glassy distal ejecta that are found in the region of Daoukro (Côte d’Ivoire) as well as offshore West Africa in deep sea sediments. All these unique features, together with the lake sediments recording the climate of the past million years, led to a comprehensive international drilling project by ICDP in 2004. In addition, an enigmatic ring pattern is observed for potassium (K) concentration in airborne radiometric maps. We have recently elucidated the post-impact alteration mechanism, controlled by the erosion rate and topography of the crater. These results are based on morphological analysis, field observations, and cosmogenic nuclide measurements, and have also been independently confirmed by numerical erosion modeling. This study also demonstrated that the morphology of the ejecta, characterized by an annular moat and a distal ridge, is analogous to that of fluidized ejecta observed on Mars, used as a proxy to decipher the history of water reservoirs of the red planet. Altogether, these results emphasize that Lake Bosumtwi remains an important object to address outstanding questions in geomorphology and impact science, with great relevance for planetary science. The lake itself is a resource for a growing population, and a recreational area with much potential for geo/astro-education. Bosumtwi was recently selected as an IUGS Geoheritage site and was recognized in 2016 by UNESCO as a biosphere reserve. The 5th edition of the Arab and Africa Impact Cratering and Astrogeology Conference (AICAC V), held in Accra in November 2025, followed by a field excursion, was a decisive step strengthening collaboration in planetary science with Ghanaian scientists. It supported several initiatives to both preserve and promote this unique natural site for astro/geo-education.
| Stream | Education, Development and Outreach |
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