^1,2,3Steven J. Jaret,⁴William R. Hyde,⁵Leah Shteynman
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14354]
¹Department Physical Sciences, Kingsborough College CUNY, Brooklyn, New York, USA
²Department Earth and Environmental Sciences, CUNY Graduate Center, New York, New York, USA
³Department Earth and Planetary Sciences, American Museum of Natural History, New York, New York, USA
⁴Department of Geology, Lund University, Lund, Sweden
⁵School of Earth and Space Exploration, Arizona State University, Tempe, Arizona, USA
Published by arrangement with John Wiley & Sons

New mapping and laboratory studies of the impactites at the Gardnos impact structure (Norway) show a variety of impact-deformed rocks. Our mapping and petrographic analyses have subdivided these breccias into three distinct categories: (a) melt-bearing sueivitic breccias, melt-bearing polymict breccias; (b) melt-free, polymict lithic impact breccias; and (c) monomict lithic impact breccias. This illustrates the dynamic nature of crater floor processes where mixing occurs in multiple ways. Feldspar grains exhibit evidence of intense shear, micro-faults, and alternate twin deformation in feldspar. We also observe the development of additional, amphibole-like planar elements (or cleavage) in biotite. Melt-bearing breccias contain carbon concentrations up to an order of magnitude higher than the target rocks. Unusual textures of carbon petrographically associated with shock and post-shock features in feldspars suggest significant postimpact hydrothermal mobilization of carbon within these rocks. Gardnos, therefore, represents an important terrestrial analog for understanding a suite of impact- and postimpact geologic processes.