Tokt22 Daniel SBP norsk nett — Daniel Wiberg watching the sub-bottom sediment echosounder profile while crossing the crater.

Passing the Mjølnir meteorite crater on the way to Svalbard

Expedition diary: While travelling towards Kvitøya and the northeastern part of Svalbard, we noticed a strangely shaped area on the map, and decided to cross it and acquire some new seabed data with a better resolution.

Author: Valérie Bellec, Daniel Hesjedal Wiberg, Lilja Rún Bjarnadóttir and Henning Jensen, Geological Survey of Norway

The area looks like a triangle, 10 x 15 km wide, which is sticking out of the Bjørnøya Trough.

This area has previously been identified as a meteorite crater that occurred more than 140 million years ago, and at its deepest is about 40 km wide. In the following tens of millions of years, the area has been buried under vast amounts of sediments. During the glaciations, large ice sheets repeatedly eroded wide areas in the Barents Sea, exposing the top of the crater.

Overview map of the western Barents Sea, with zoom-in of the Mjølnir meteorite crater. IBCAO bathymetry data.

When the meteorite hit the ocean, this part of the Barents Sea was roughly around the same latitude as Bergen-Kristiansand (58° - 60°N). But has since been shifted north to 73°N due to the plate tectonic movements.

Upon entering the crater, we discovered that the rim is about 70 metres taller than the surrounding area and is bare of sediments. As we exited the crater, we saw that the rim is only 15 metres tall on this side, and partly covered by till sediments deposited by ice sheets. The lower height of the northern side of the crater rim is partially due to our travel direction, but may also be due to difference in glacial erosion or the angle of the impact.

Grid and profiles — 10 m multibeam grid and sub-bottom profiler acquired on the top of the Mjølnir crater during this cruise.

Reference:
Tsikalas et al., 1998. The anatomy of a buried complex impact structure: The Mjølnir Structure, Barents Sea. Journal of Geophysical Research 103(B12), pages 30469-30483.