The Mjølnir impact structure in time and space

Abstract

The Mjølnir impact crater was discovered in seismic reflection data in the 1990's and the detailed structure is well established. The submarine crater, situated in the southwestern Barents Sea, is believed to have a crater diameter of about 40 km, and a shallow relief (About 50 m). The crater is buried under a layer of sediments. Stratigraphic relationships (drill core 7329\/03-U01) indicate a Cretaceous formation age around 140 Ma. This structure is a well-studied crater, but still the dimensions and subsequent history need further investigation.\rHere, density and magnetic susceptibility measurements of core samples are presented and used to interpret a newly available aeromagnetic survey (BAS-06) abd gravity data, and to forward model the potential field anomaly data if the area, in order to better constrain the signature of the crater. Preliminary modelling suggests that the crater diameter is overestimated. We have also developed a detailed Cretaceous palaeogeographic reconstruction at the time of the impact. This investigation is conducted to support future drilling at the Mjølnir impact site.