Annama H chondrite-Mineralogy, physical properties, cosmic ray exposure, and parent body history

The fall of the Annama meteorite occurred early morning (local time) on April 19, 2014 on the Kola Peninsula (Russia). Based on mineralogy and physical properties, Annama is a typical H chondrite. It has a high Ar-Ar age of 4.4 Ga. Its cosmic ray exposure history is atypical as it is not part of the large group of H chondrites with a prominent 7-8 Ma peak in the exposure age histograms. Instead, its exposure age is within uncertainty of a smaller peak at 30 +/- 4 Ma. The results from short-lived radionuclides are compatible with an atmospheric pre-entry radius of 30-40 cm. However, based on noble gas and cosmogenic radionuclide data, Annama must have been part of a larger body (radius >65 cm) for a large part of its cosmic ray exposure history. The Be-10 concentration indicates a recent (3-5 Ma) breakup which may be responsible for the Annama parent body size reduction to 30-35 cm pre-entry radius.Peer reviewe

The Sariçiçek Howardite Fall in Turkey: Source Crater of HED Meteorites on Vesta and İmpact Risk of Vestoids

The Sariçiçek howardite meteorite shower consisting of 343 documented stones occurred on 2 September 2015 in Turkey and is the first documented howardite fall. Cosmogenic isotopes show that Sariçiçek experienced a complex cosmic ray exposure history, exposed during ~12–14 Ma in a regolith near the surface of a parent asteroid, and that an ~1 m sized meteoroid was launched by an impact 22 ± 2 Ma ago to Earth (as did one third of all HED meteorites). SIMS dating of zircon and baddeleyite yielded 4550.4 ± 2.5 Ma and 4553 ± 8.8 Ma crystallization ages for the basaltic magma clasts. The apatite U-Pb age of 4525 ± 17 Ma, K-Ar age of ~3.9 Ga, and the U,Th-He ages of 1.8 ± 0.7 and 2.6 ± 0.3 Ga are interpreted to represent thermal metamorphic and impact-related resetting ages, respectively. Petrographic, geochemical and O-, Cr- and Tiisotopic studies confirm that Sariçiçek belongs to the normal clan of HED meteorites. Petrographic observations and analysis of organic material indicate a small portion of carbonaceous chondrite material in the Sariçiçek regolith and organic contamination of the meteorite after a few days on soil. Video observations of the fall show an atmospheric entry at 17.3 ± 0.8 kms-1 from NW, fragmentations at 37, 33, 31 and 27 km altitude, and provide a pre-atmospheric orbit that is the first dynamical link between the normal HED meteorite clan and the inner Main Belt. Spectral data indicate the similarity of Sariçiçek with the Vesta asteroid family (V-class) spectra, a group of asteroids stretching to delivery resonances, which includes (4) Vesta. Dynamical modeling of meteoroid delivery to Earth shows that the complete disruption of a ~1 km sized Vesta family asteroid or a ~10 km sized impact crater on Vesta is required to provide sufficient meteoroids ≤4 m in size to account for the influx of meteorites from this HED clan. The 16.7 km diameter Antonia impact crater on Vesta was formed on terrain of the same age as given by the 4He retention age of Sariçiçek. Lunar scaling for crater production to crater counts of its ejecta blanket show it was formed ~22 Ma ago

Advances in Analysis of the Fe-Ni-Co Alloy and Iron-Bearing Minerals in Meteorites by Mössbauer Spectroscopy with a High Velocity Resolution

Meteorites are the space messengers bringing us the unique information about the Solar System formation and evolution as well as about the effects of various extreme space conditions on meteorites and their parent bodies. The main iron-bearing compounds in meteorites are Fe-Ni-Co alloy, olivine (Fe, Mg)2SiO4, orthopyroxene (Fe, Mg)SiO3, clinopyroxene (Ca, Fe, Mg)SiO3, troilite FeS, chromite FeCr2O4, hercynite FeAl2O4, ilmenite FeTiO3, daubréelite FeCr2S4, schreibersite (Fe, Ni)3P and some other compounds. Therefore, 57Fe Mössbauer spectroscopy was successfully applied for the analyses of various meteorites for about 60 years of experience. The development of Mössbauer spectrometers with a high velocity resolution, i.e., with a high discretization of the velocity reference signal up to 212, provides much better adjustment to resonance and significantly increases the spectra quality and analytical possibilities of Mössbauer spectroscopy. In fact, this permits us to decompose the complex Mössbauer spectra of meteorites using the larger number of spectral components related to reliable compounds in comparison with the results obtained using conventional Mössbauer spectrometers with discretization of the velocity reference signal up to 29. In the present review we consider the results and advances of various meteorites analyses by means of Mössbauer spectroscopy with a high velocity resolution

Comparison of the Fe-57 hyperfine interactions in silicate phases in Saricicek howardite and some ordinary chondrites

International Conference on Hyperfine Interactions and their Applications (HYPERFINE) -- FEB 10-15, 2019 -- INDIAWOS: 000467083400005Silicate crystals have different thermal history in non-differentiated and differentiated meteorites. This leads to some differences in the Fe2+ and Mg2+ distribution between the M1 and M2 sites in olivine, orthopyroxene and clinopyroxene crystals in stony meteorites resulting in small variations in the Fe local microenvironment. For this reason, a comparison of Mossbauer hyperfine parameters for the Fe-57 in the M1 and M2 sites in orthopyroxene and Ca-rich clinopyroxene for non-differentiated NWA 6286 LL6, NWA 7857 LL6 and Tsarev L5 ordinary chondrites and differentiated Saricicek howardite was carried out. The results obtained demonstrated small variations in quadrupole splitting and isomer shift for the studied non-differentiated and differentiated stony meteorites.Ministry of Science and Higher Education of the Russian Federation [3.1959.2017/4.6]; Act 211 Government of the Russian Federation [02.A03.21.0006]; Scientific and Technological Research Council of TurkeyTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [MFAG/113F035]The authors wish to thank G.A. Yakovlev and Dr. M.S. Karabanalov for the help with scanning electron microscopy with energy dispersive spectroscopy. This work was supported by the Ministry of Science and Higher Education of the Russian Federation (the Project No 3.1959.2017/4.6) and Act 211 Government of the Russian Federation, contract No 02.A03.21.0006. O.U. acknowledges the Scientific and Technological Research Council of Turkey (the Project number: MFAG/113F035)

Spinels in Meteorites: Observation Using Mössbauer Spectroscopy

In this mini-review, we consider the results of various meteorite studies using Mössbauer spectroscopy with a high velocity resolution in order to reveal the minor spectral components related to spinels such as chromite, hercynite, magnesiochromite, magnesioferrite and daubréelite in bulk meteorite matter or in some extracted phases. Spinels observation in the Mössbauer spectra is supported by characterization of the studied samples by means of optical and scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction and magnetization measurements. Mössbauer parameters obtained for extraterrestrial spinels are compared with those obtained for terrestrial analogs published in the literature

Study of Dronino Iron Meteorite Weathering in Clay Sand Using Mössbauer Spectroscopy

Weathering products of two fragments of Dronino iron ungrouped meteorite found in the wet and drier clay sand were studied using X-ray diffraction and Mössbauer spectroscopy with a high velocity resolution. The products of metal oxidation in the internal and external surface layers were different for both fragments. The weathering products in fragment found in the wet clay sand contain magnetite (Fe₃O₄), maghemite (γ-Fe₂O₃), goethite (α-FeOOH) and probably ferrihydrite (5Fe₂O₃∙9H2O) while those in fragment found in drier clay sand contained ferric hydrous oxides (FeOOH) and siderite (FeCO3) mainly. Concretions found near the first fragment contain ferric hydrous oxides (FeOOH) mainly. <br><a rel="license" href="http://creativecommons.org/licenses/by/4.0/"><img alt="Creative Commons License" style="border-width:0" src="https://i.creativecommons.org/l/by/4.0/80x15.png" /></a> This work is licensed under a <a rel="license" href="http://creativecommons.org/licenses/by/4.0/">Creative Commons Attribution 4.0 International License</a>