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Systematic survey of K, Th, and U signatures in airborne radiometric data from Australian meteorite impact structures: Possible causes of circular features and implications, in Reimold, W.U., and Koeberl, C., eds., Large Meteorite Impacts and Planetary Evoluti

Airborne radiometric (gamma-ray) data provide estimates of the concentrations of potassium (K), thorium (Th), and uranium (U) in soil, regolith, and bedrock. Radiometric data constitute an important source of geochemical information, commonly used in mineral exploration and for geological mapping of Earth and other planets. Airborne radiometric data have rarely been applied to the exploration and analyses of impact structures, in contrast with other conventional geophysical tools (e.g., gravimetry, magnetism, and seismic re?ection/refraction). This work represents the frst systematic survey of the K, Th, and U radiometric signatures of Australian impact structures, based on the continent-wide airborne radiometric coverage of Australia. We frst formulated several hypotheses regarding the possible causes of formation of circular radiometric patterns associated with impact structures. Then, the radiometric signatures of 17 exposed impact structures in Australia were documented. Our observations confrmed the supposition that impact structures are commonly associated with circular radiometric patterns. We then selected the fve structures with the most prominent circular radiometric patterns (Gosses Bluff, Lawn Hill, Acraman, Spider, and Shoemaker), and we discuss the possible origin of these anomalies. Based on these fve case studies, we argue that such patterns result from either crustal deformation induced by the impact event and/or from postimpact superfcial processes controlled by the crater topography. This work also suggests that airborne radiometric data may be useful, in combination with other geophysical tools, in the search for new possible impact structures.

Auteur(s) : Niang, C.A.B., Baratoux, D., Diallo, D.P., Rochette, P., Jessell, M.W., Reimold, W.U., Bouley, S., Vanderhaeghe, O., Faye, G., and Lambert, P.,
Année de publication : 2021
Revue : Geological Society of America
N° de volume : 550
Type : Article
Mise en ligne par : FAYE Gayane