¹Jennifer D. Newman ¹Christopher D. K. Herd
¹Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta, Canada

The Whitecourt meteorite impact crater, Alberta, Canada is a rare example of a well-preserved small impact structure, with which thousands of meteorite fragments are associated. As such, this crater represents a unique opportunity to investigate the effect of a low-energy impact event on an impacting iron bolide. Excellent documentation of meteorite fragment locations and characteristics has generated a detailed distribution map of both shrapnel and regmaglypted meteorite types. The meteorites’ distribution, and internal and external characteristics support a low-altitude breakup of the impactor which caused atmospherically ablated (regmaglypted) meteorites to fall close to the crater and avoid impact-related deformation. In contrast, shrapnel fragments sustained deformation at macro- and microscales resulting from the catastrophic disruption of the impactor. The impactor was significantly fragmented along pre-existing planes of weakness, including kamacite lamellae and inclusions, resulting in a bias toward low-mass ((<100 g) fragments. Meteorite mineralogy was investigated and the accessory minerals were found to be dominated by sulfides and phosphides with rare carlsbergite, consistent with other low-Ni IIIAB iron meteorites. Considerations of the total mass of meteoritic material recovered at the site relative to the probable fraction of the impactor that was preserved based on modeling suggests that the crater was formed by a higher velocity, lower mass impactor than previously inferred.

Reference
Newman JD, Herd CDK (2015) Mineralogy, petrology, and distribution of meteorites at the Whitecourt crater, Alberta, Canada. Meteoritics&Planetary Science (in Press)
Link to Article [DOI: 10.1111/maps.12422]

Published by arrangement with John Wiley&Sons

¹Masarik, J., ¹Beňo, J.
¹Department of Nuclear Physics and Biophysics, Comenius University, Bratislava, Slovakia

The shape of meteorites is one of the major factors influencing the production of cosmogenic nuclides. Numerical simulations using the Los Alamos Code System (LCS) particle production and transport codes were done to investigate particle fluxes and production rates of cosmogenic nuclides 10Be, 26Al, and 60Co in meteoroids of spherical, ellipsoidal, and cylindrical shapes. The calculations show that fluxes of nuclear active particles and also production rates of cosmogenic nuclides are sensitive to the shape of the irradiated parent body.

Reference
Masarik J, Beňo J (2015) Effects of meteoroid shape on cosmogenic nuclide production processes. Meteoritics & Planetary Science (in Press)
Link to Article [doi: 10.1111/maps.12423]

Published by arrangement with John Wiley&Sons