A Raman Spectroscopic Study of Carbon Phases in Impact Melt Rocks and Breccias from the Gardnos Impact Structure, Norway

Introduction: The Gardnos impact structure [1] is located in southern Norway (60°40 ́N; 9°00 ́E), approximately 125 km northwest of Oslo, Norway. The structure, originally about 5 km in diameter, has been deeply eroded. It lacks any distinctive circular form and is now represented by outcrops of impactproduced breccias, both lithic and melt-bearing. Its impact origin has been convincingly established from three lines of evidence [1]: (1) the presence of meltbearing breccias containing granitic rock fragments with definite Planar Deformation Features (PDFs) in quartz and feldspar; (2) the demonstration, using chemical mixing models, that the breccia compositions could be produced by mixing the exposed target rocks; (3) an extraterrestrial signature from the projectile in the breccias, established using osmium-isotope analyses.