Meteorites and impact structures in Chad

P. Rochette, J.C. Doumnang, J. Gattacceca, Y. Quesnel

Journal of African Earth Sciences
Volume 210, February 2024, 105137


“The large surface of Chad (fifth largest country in Africa) as well as a desert climate over much of its area, makes the country a potentially prolific place to recover meteorites and identify impact structures. However, only two meteorite finds have so far been reported, from Tibesti, and two probable falls have been recovered in the vicinity of the capital N’Djamena in the early 1960s. We report on two more recent meteorite falls, Andila and Boutel-Fil, occurring in 2014 and 2023, respectively. All these meteorites are ordinary chondrites, one LL, one L and four H. Chad has two proven eroded impact structures circa 15–20 km in diameter: Aorounga and Gweni-Fada. A number of potential impact structures have also been proposed. The most promising ones are the Faya, Lac Iro and Mousso structures, with diameters of 2, 13 and 3.5 km, respectively. Other previously proposed structures, near the Libyan border, are most probably of magmatic origin. Based on geomorphological and geological arguments, the presence of the Iro lake cannot be readily explained by any process other than impact and its investigation should be a priority based on its size and potential interest as a paleoclimatic recorder. We also suggest that a 35 km diameter structure named Ehi Gidaha, buried under the Devonian sandstones from south Tibesti, may be of impact origin. All proven or potential impact structures are located in the Sahara part of northern Chad, except Lac Iro.”