Radiometric method
This section explains how the radiometric method, including radiocarbon dating, was used in the Bosumtwi impact crater. Baratoux et al.(2019b ) used a radiometric survey combined with detailed topographic analysis, including roughness mapping, to map near-surface K, Th, and U concentrations and field observations. The Geological Survey of Ghana provided two airborne radiometric surveys for this investigation. One of them (Aerodat) was taken with a 200 m gridded line spacing. It was properly calibrated and delivered absolute readings for K (weight percent), Th (ppm), and U surface concentrations (ppm). Unfortunately, only half of the Bosumtwi impact crater was covered by this survey. The second survey covers the full impact structure and has a grid line spacing of 400 m, although it was not calibrated. The two airborne surveys were combined to create a gridded data collection of K, Th, and U concentrations with a 50 m/pixel resolution. The authors obtained evidence that the moat and outer ring are features inherited from the impact event and represent the partially eroded ejecta layer of the Bosumtwi impact structure.
Peck et al. (2004 ) used the results from the Accelerator Mass Spectrometer (AMS) radiocarbon dating process and produced an age model from a suite of 30 AMS 14C dates from cores 12P, 15P, and 19P. While a distinct downcore trend of older sediment ages exists in these data, there is a significant amount of scattering below 700 cm standardised depth. The calibrated age range is between 3321 years for the sample taken at 90.0 cm depth and 24,355 years for the sample taken at 844.1 cm depth.