According to a new study led by Kurt Kjær from the University of Copenhagen, Denmark, a semicircular lobe of Hiawatha Glacier in northwestern Greenland conceals a 31 km-diameter structure that may have formed as a complex impact crater during the Pleistocene. The circular morphology of the structure includes an elevated rim and a subdued central uplift that hides underneath one kilometer of ice. In addition, subsurface ice debris visible in radar images and grains of glacial outwash sediment identified as shocked quartz, breccia, and melt glass with a meteorite-like geochemical fingerprint make an impact origin of the “Hiawatha crater” likely. Geochemical analysis of the sediment suggests that the impactor was an iron asteroid. The team’s analysis suggests the impact is pre-Holocene and likely postdates the Pleistocene Greenland Ice Sheet, but the exact age of the impact remains unknown.
Source: Kjær, K. et al. (2018) A large impact crater beneath Hiawatha Glacier in northwest Greenland. Science Advances 4 (11), 11 p. DOI: 10.1126/sciadv.aar8173. http://advances.sciencemag.org/content/4/11/eaar8173
For an overview of the study, click here.