The Lake Bosumtwi impact crater, Ghana

Geological Society of America Bulletin
By: , and 

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Abstract

The 1-m.y.-old Bosumtwi Crater, Ghana, has a nearly circular shape with a rim diameter of 11 km north-south and 10 km east-west. It is surrounded by a circular depression and an outer ridge of diameter 20 km. Polymict breccias averaging at least 20 m thick with clasts as much as 5 m long occur on the outer ridge, and the crater rim shows in situ shattered rock. Patches of suevite have been found in the circular depression north and south of the crater.

Analogy with better-known craters suggests that Bosumtwi has a central uplift rising to 200 m beneath the lake floor. An aeromagnetic anomaly of amplitude 50 nanotesla (nT) over the northern half of the lake is interpreted as due to a layer of magnetized fallback breccia beneath the lake sediments. The normal polarity of the breccia shows that the crater was formed during the normal Jaramillo event of 0.97 to 0.85 m.y. ago, which agrees with the magnetic stratigraphy of the related Ivory Coast microtektites. A regional gravity survey indicates a negative Bouguer anomaly over the crater. There is some geochemical evidence that the meteorite was an iron, and its mass and energy are suggested as about 108 tons and 3 × 1019 joules or 7.3 × 103 megatons.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title The Lake Bosumtwi impact crater, Ghana
Series title Geological Society of America Bulletin
DOI 10.1130/0016-7606(1981)92%3C342:TLBICG%3E2.0.CO%3b2
Volume 96
Issue 6
Year Published 1981
Language English
Publisher Geological Society of America
Contributing office(s) Earth Resources Observation and Science (EROS) Center
Description 8 p.
First page 342
Last page 349
Country Ghana
Other Geospatial Lake Bosumtwi
Online Only (Y/N) N
Additional Online Files (Y/N) N
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