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17. Bosumtwi, Ghana This well-preserved young crater, situated in crystalline bedrock of the West African Shield, is filled almost entirely by Lake Bosumtwi, which has a diameter of about 8 kilometers. The crater rim reaches elevations of about 300 meters above the lake level. Chemical, isotopic, and age studies demonstrate that the crater is the most probable source for the Ivory Coast tektites, which are found on land in Ivory Coast, West Africa, and as microtektites in nearby ocean sediments. The crater is excavated in 2.1–2.2-billion-year-old metasediments and metavolcanics of the Birimian Supergroup. The target rocks do not show any unambiguous evidence of shock metamorphism. Distinct impact-characteristic shock effects were identified only in clasts within suevite-derived melt fragments. The compositional range of the target rocks is significantly wider than that of the Ivory Coast tektites, but overlaps the tektite compositions. In this photo the crater lake is partly obscured by clouds, which is commonly the case in the area. Space
shuttle image STS51I-39-031. Right click here to download a high-resolution version of the image (10.6 MB) |
