The irregular base Cretaceous reflector offshore Mid Norway: a possible result for the Mjølnir impact in the Barents Sea

Abstract

Since the time of the early seismic investigations offshore Mid Norway around 1970, a very characteristic bedrock reflector with a densely small-faulted appearance has been noted, mapped and eventually assigned a base Cretaceous age. The irregular shape of the reflector has been ascribed to tectonic activity, but without really providing a full explanation as to why and how it happened. The Mjølnir impact event in the Barents Sea about 142 million years ago may provide this explanation. Within the present accuracy of seismic interpretation and dating, the impact and faulting apparently occurred simultaneously. If the inferred mega-waves from the impact were strong enough, they would have caused intense disturbance over large areas. Geotechnical evaluations show that the formation of the irregular base Cretaceous reflector could be compatible with the expected results from the modelled impact mega-waves on the soft clay deposits forming the sea bed offshore Mid Norway at that time. If the base Cretaceous faulting was caused by the Mjølnir event, it will represent an important geohazard marker demonstrating the distant effects of extraterrestrial impacts.