¹William R. HYDE,²Adam A. GARDE,²Nynke KEULEN,²Sebastian N. MALKKI,^3,4Steven J. JARET,⁵Tod WAIGHT,⁶Pierre BECK,⁷Iain McDONALD,¹Nicolaj K. LARSEN
Meteoritics & Planetary Science (in Press) Open Access Link to Article [doi: 10.1111/maps.13987]
¹Globe Institute, University of Copenhagen, Copenhagen K, Denmark
²Geological Survey of Denmark and Greenland, Copenhagen K, Denmark
³Department of Earth and Planetary Sciences, American Museum of Natural History, New York, New York, USA
⁴Department of Physical Sciences, Kingsborough Community College, City University of New York, Brooklyn, New York, USA
⁵Department of Geosciences and Natural Resource Management (Geology Section), University of Copenhagen, Copenhagen K,Denmark
⁶Universit ́e Grenoble Alpes, CNRS, IPAG, Grenoble, France
⁷School of Earth and Environmental Sciences, Cardiff University, Cardiff, UK
Published by arrangement with John Wiley & Sons

Impact melt rocks formed during hypervelocity impact events are ideal forstudying impact structures. Here, we describe impact melt rock samples collected proximalto the 31 km wide 58 Ma Hiawatha impact structure, northwest Greenland, which iscompletely covered by the Greenland Ice Sheet. The melt rocks contain diagnostic shockindicators (e.g., planar deformation features [PDF] in quartz and shocked zircon) and formthree groups based on melt textures and chemistry: (i) hypocrystalline, (ii) glassy, and (iii)carbonate-based melt rocks. The exposed foreland directly in front of the structure consistsof metasedimentary successions and igneous plutons; however, the carbonate-basedimpactites indicate a mixed target sequence with a significant carbonate-rich component.Well-preserved organic material in some melt rocks indicates that North Greenland at thetime of impact was host to abundant organic material, likely a dense high-latitude temperateforest. Geochemical signatures of platinum-group elements in selected samples indicate anextraterrestrial component and support previous identification of a highly fractionated ironimpactor in glaciofluvial sand. Our results illustrate the possibility to study impact structureshidden beneath a thick ice sheet based on transported samples and this opens a new avenuefor identifying other potential impact craters in Greenland and Antarctica.