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Z Wiki.Meteoritica.pl

Wersja z 16:08, 7 paź 2025

Bischoff Addi, Patzek Markus Barrat, Jean-Alix, Bartel Stig, Berndt Jasper, Busemann Henner, Rocco Tommaso Di, Ek Mattias, Fehr Manuela A., Heinlein Dieter, Krietsch Daniela, Lehnert Björn, Maden Colin, Marchhart Oscar, Martschini Martin, Merchel Silke, Pack Andreas, Patzer Andrea, Pichotta Marie, Reitze Maximilian P., Schmitt-Kopplin Philippe, Schönbächler Maria, Thannheiser Leon, Weber Iris, Wieser Alexander, Wimmer Karl, (2025), he fall of the Haag (LL4-6) chondrite breccia—Just 8 years after the nearby fall Stubenberg (LL6), Meteoritics & Planetary Science, open access, 2025, ss. 27 (abstrakt). Plik doi.

Abstract: On October 24, 2024, an impressive fireball was visible over Austria. After the possible strewn field was calculated, the first sample of the Haag meteorite, with a mass of 8.76 g, was discovered on November 2, 2024, 8 days after the fireball event. Four more samples were found afterward putting the total sample mass at about 151 g. Short-lived radionuclides were measured shortly after recovery on a small sample, which was also used for almost all analyses presented here. Results confirm that the Haag meteorite derived from the bolide fireball event. Haag is a severely fragmented ordinary chondrite breccia and consists of typical equilibrated and recrystallized lithologies (LL4-6) as well as impact-related lithic clasts, such as dark, fine-grained impact breccias. Most fragments are highly recrystallized (type 6), but some show a well-preserved chondritic texture, which is of petrologic type 4 since the olivines are equilibrated. The olivines in the bulk rock have Fa contents of 29.5±0.5 mol%, whereas the low-Ca pyroxenes have compositions of Fs_23.9±1.4Wo_1.6±0.7 with slightly variable Fs contents up to 28 mol%. However, the occurrence of type 3 fragments in other parts of the rock cannot completely be ruled out. Many clasts are moderately shocked (S4; C-S4). Using the fragment with the lowest degree of shock to determine the bulk rock's shock degree, Haag has an overall shock degree of S2 (C-S2). The LL chondrite classification is also supported by O isotope data, the results of bulk chemical analysis, and the physical properties of density and magnetic susceptibility. The nucleosynthetic Ti and Cr isotope data confirm that Haag is an ordinary chondrite, related to the noncarbonaceous (NC) meteorites. Haag does not contain detectable amounts of solar wind-implanted noble gases, and we rule out any substantial exposure at the direct surface of the parent body. Based on noble gases, Haag has an exposure age of 21–24 Ma and a pre-atmospheric meteoroid radius of 20–85 cm with a sample depth between 4 and 5 cm below the meteoroid surface, consistent with constraints from cosmogenic radionuclides. The soluble organic compositions of Haag are consistent with the profiles of the Stubenberg (LL6) breccia and show characteristics consistent with the complex shock, brecciation, and lithification history of the breccia. Haag and Stubenberg fell near each other (110 km away) within just 8 years. Since only 8.5% (about 110) of meteorite falls worldwide are LL chondrites, it is remarkable that two LL chondrites fell near each other in such a short time.

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