Meteoritics & Planetary Science 54, Nr 11, 2698–2709 (2019) doi: 10.1111/maps.13381 A TEM and EELS study of carbon in a melt fragment from the Gardnos impact structure Paula LINDGREN 1*, Lydia HALLIS 2, Fredrik S. HAGE3, Martin R. LEE 2, John PARNELL4, Anders PLAN 1, Alistair DOYE5, and Ian MACLAREN5 1Department of Geology, Lund University, Solvegatan€ 12, 223 62 Lund, Sweden 2School of Geographical & Earth Sciences, University of Glasgow, Glasgow G12 8QQ, UK 3SuperSTEM Laboratory, SciTech Daresbury Campus, Daresbury WA4 4AD, UK 4School of Geosciences, University of Aberdeen, Aberdeen AB24 3UE, UK 5School of Physics & Astronomy, University of Glasgow, Glasgow G12 8QQ, UK *Corresponding author. E-mail:
[email protected] (Received 14 January 2019; revision accepted 29 July 2019) Abstract–A carbon-rich melt fragment from the Gardnos impact structure has been studied for a better understanding of the preservation and structural form(s) of carbon that have been processed by impact melting. The carbon was analyzed in situ in its original petrographic context within the melt fragment, using high-resolution techniques including focused ion beam-transmission electron microscopy and electron energy loss spectroscopy. Results show that the carbon is largely uniform and has a nanocrystalline grain size. The Gardnos carbon has a graphitic structure but with a large c/a ratio indicating disorder. The disorder could be a result of rapid heating to high temperatures during impact, followed by rapid cooling, with not enough time to crystallize into highly ordered graphite. However, temperature distribution during impact is extremely heterogenous, and the disordered Gardnos carbon could also represent material that avoided extreme temperatures, and thus, it was preserved.