Browsing by Author "Muszyński, Andrzej"
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Item Shock veins in the Sahara 02500 ordinary chondrite(Wydawnictwo Naukowe UAM, 2012-09-12T07:50:10Z) Owocki, Krzysztof; Muszyński, AndrzejA specimen of the Sahara 02500 ordinary chondrite contains shock-produced veins consisting of recrystallised fine- grained pyroxenes that include small droplets of Ni-rich metal. Non-melted olivines and pyroxenes show planar deformations filled by shock-melted and -polluted metal and troilite. Shock-melted feldspathic glass is present close to the shock veins. Geothermometric estimations indicate that the meteorite locally experienced moderate shock metamorphism with a minimum local peak temperature above 1400ºC, resulting in partial melting of Ca-poor pyroxene and full melting of feldspars, metal and sulphides. The mineral assemblage in the shock veins suggests a pressure during melt recrystallisation below 10 GPa.Item Small impact cratering processes produce distinctive charcoal assemblages(2022-11) Losiak, Anna; Belcher, C. M.; Plado, J.; Jõeleht, A.; Herd, C. D. K.; Kofman, R. S.; Szokaluk, Monika; Szczuciński, Witold; Muszyński, Andrzej; Wild, E. M.; Baker, S. J.The frequency of crater-producing asteroid impacts on Earth is not known. Of the predicted Holocene asteroid impact craters of <200 m diameter, only ~30% have been located. Until now there has been no way to distinguish them from “normal” terrestrial structures unless pieces of iron meteorites were found nearby. We show that the reflective properties of charcoal found in the proximal ejecta of small impact craters are distinct from those produced by wildfires. Impact-produced charcoals and wildfire charcoals must derive from different heating regimes. We suggest that charcoal with specific reflective properties may help to recognize the meteoritic origin of small craters.