Formation and shock impact history of the Csatalja ordinary chondrite

1,2Ildiko Gyollai,2,3Ákos Kereszturi,4,5Elias Chatzitheodoridis,6Zsolt Kereszty,1,2Máté Szabó,2,7Csilla Király,2,7Zoltan Szalai
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13931]
1Institute for Geological and Geochemical Research, Research Centre for Astronomy and Earth Sciences, Eötvös Loránd Research Network, Budaorsi ut 45, H-1112 Budapest, Hungary
2CSFK, MTA Centre of Excellence, Konkoly Thege Miklós út 15-17, H-1121 Budapest, Hungary
3Konkoly Thege Miklos Astronomical Institute, Research Centre for Astronomy and Earth Sciences, Eötvös Loránd Research Network, Konkoly Thege Miklós út 15-17, H-1121 Budapest, Hungary
4Department of Geological Sciences, School of Mining and Metallurgical Engineering, National Technical University of Athens 9, Heroon Polytechneiou str., GR-15780 Zografou, Athens, Greece
5Network of Researchers on the Chemical Evolution of Life (NoRCEL), LS2 9JT Leeds, UK
6Private Collector at IMCA (IMCA#6251) and Meteoritical Society, H-9010 Győr, Hungary
7Geographical Research Institute, Research Centre for Astronomy and Earth Sciences, Eötvös Loránd Research Network, Budaorsi ut 45, H-1112 Budapest, Hungary
Published by arrangement with John Wiley & Sons

The analysis of the Csatalja H4 chondrite (which was found in August 2012) suggests shock-related textures and spatial inhomogeneities, indicating a complex geological history. In the most heavily fractured and sheared units, small opaque grains and older fractures have locally enhanced the shock effect, producing melt. While the impact textures were evident in most units of the meteorite, mechanical shearing is apparent in only two units, suggesting that these units might have been present at somewhat different locations inside the parent body. Shearing also occurred at the border of the so-called xenolith unit, confirming its mechanical mixing with the other units. Besides fragmentation and melting, chemical changes due to impact have also been identified, producing compositional homogenization of olivines in 30% of the investigated area of the sample’s thin section (23 mm2), and moderate accumulation of Fe, Ca, and Na in the strongly shocked zones, initiating crystallization of feldspar in veins with a specific spatial distribution (feldspar glass with metal–sulfide globules). Analyzing the high P–T minerals, the peak shock pressure and temperature values differed substantially in the various units, ranging between 2 and 17 GPa, 100 and >1200 °C. The xenolith unit crystallized more slowly after the impact event and does not show shock impact alterations, suggesting that it was formed in a deeper region of the parent body. This was later shifted to its current surroundings and was lithified (fixed) to the rest of the sample. This “randomly selected” Csatalja sample provides information on the range of the formation temperatures, pressures, and processes that contributed to the heterogeneity of meteorites at the mm spatial scale, in general. The identified heterogeneity is a result not purely of the shock effects but also of the different pre-shock structural characteristics. The shock also mixed fragments mechanically that have been formed at different environments, with at least several dozens or even 100 m depth in the parent body.

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