Impact Structure and Morphology

Abstract

The Mjolnir crater (Fig. 3.1) was first interpreted as an impact structure by Gudlaugsson (1993) based on its geophysical signature and overall geological setting. This inference was derived from a limited amount of multichannel seismic profiles, and regional gravity and magnetic profiles. The impact hypothesis prompted the acquisition of high-resolution seismic, gravity and magnetic profiles by the Norwegian Defence Research Establishment in 1992 and 1993. Together with the previously acquired shallow and conventional multichannel seismic profiles, these data comprise an extensive and unique geophysical database (Fig. 3.2 and Table 3.1). In addition, stratigraphic, and sedimentological information exists from two shallow boreholes, one near the center (7329/03-U-01) and another ~30 km north-northeast from the crater periphery (7430/10-U-01) (Fig. 3.2). The detailed seismic reflection correlation to the two boreholes, together with the existing regional grid of seismic profiles on the Bjarmeland Platform, have made it possible to correlate the main seismic sequence boundaries at Mjolnir to the established stratigraphic framework of the Barents Sea (Worsley et al. 1988; Gabrielsen et al. 1990; Richardsen et al. 1993; Smelror et al. 2002).