Characterization of iron meteorites by scanning electron microscopy, X-ray diffraction, magnetization measurements, and Mössbauer spectroscopy: Gibeon IVA

Meteoritics & Planetary Science (in Press) Link to Article [doi: 10.1111/maps.13984]
1Institute of Physics and Technology, Ural Federal University, Ekaterinburg, Russian Federation
2Department of Materials Physics, Eotvos Lorand University, Budapest, Hungary
3Racah Institute of Physics, The Hebrew University, Jerusalem, Israel
4Laboratory of Nuclear Chemistry, Institute of Chemistry, Eotvos Lorand University, Budapest, Hungary
Published by arrangement with John Wiley & Sons

Gibeon IVA iron meteorite fragment was characterized using optical microscopy,scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), X-raydiffraction (XRD), magnetization measurements, and M€ossbauer spectroscopy. Opticalmicroscopy and SEM made on the polished section of the meteorite, show the presence ofa-Fe(Ni, Co) andc-Fe(Ni, Co) phases and plessite structures. There are no troilite inclusionsobserved in the studied section. EDS studies indicate some variations in the Ni concentrations:(i) within thea-Fe(Ni, Co) phase in the range~5.00.1–~7.50.1 at% and (ii) within thec-Fe(Ni, Co) phase in the range~26.00.2–~36.10.2 at%. The latter Ni concentrationrange indicates the presence of small amount of the paramagneticc-phase in addition to theferromagneticc-phase. EDS also shows that Ni content in two plessite structures is varying inthe range~16–37 at%, which can indicate the presence of only thea2-Fe(Ni, Co) andc-Fe(Ni,Co) phases in the duplex plessite structure. This may be a result of thec-phase decompositionwith the incomplete martensitic transformation:c?a2+cdue to a faster cooling rate. XRDindicates the presence of~1.3 wt% of thec-Fe(Ni, Co) phase in Gibeon VIA. The saturationmagnetization moment of 185(2) emu g1obtained also confirms the presence of phases withlow and high Ni concentrations. The most appropriate fit of the Gibeon IVA M€ossbauerspectrum demonstrates the presence of five magnetic sextets and one paramagnetic singlet whichare assigned to the ferromagnetica2-Fe(Ni, Co),a-Fe(Ni, Co),c-Fe(Ni, Co), and paramagneticc-Fe(Ni, Co) phases. The relative average Fe contents in these phases are: 13.4% in thea2-Fe(Ni, Co) phase, 78.3% in thea-Fe(Ni, Co) phase, and 8.3% in the ferromagnetic andparamagneticc-Fe(Ni, Co) phases.

The Winchcombe fireball—That lucky survivor

1,2,3,4Sarah McMullan et al. (>10)
Meteoritics & Planetary Science (in Press) Open Access Link to Article []
1Impact and Astromaterials Research Centre, Department of Earth Science and Engineering, Imperial College London, SW7 2BP London, UK
2UK Fireball Network (UKFN), UK
3UK Fireball Alliance (UKFAll), UK
4Global Fireball Observatory (GFO), Australia
Published by arrangement with John Wiley & Sons

On February 28, 2021, a fireball dropped ∼0.6 kg of recovered CM2 carbonaceous chondrite meteorites in South-West England near the town of Winchcombe. We reconstruct the fireball’s atmospheric trajectory, light curve, fragmentation behavior, and pre-atmospheric orbit from optical records contributed by five networks. The progenitor meteoroid was three orders of magnitude less massive (∼13 kg) than any previously observed carbonaceous fall. The Winchcombe meteorite survived entry because it was exposed to a very low peak atmospheric dynamic pressure (∼0.6 MPa) due to a fortuitous combination of entry parameters, notably low velocity (13.9 km s−1). A near-catastrophic fragmentation at ∼0.07 MPa points to the body’s fragility. Low entry speeds which cause low peak dynamic pressures are likely necessary conditions for a small carbonaceous meteoroid to survive atmospheric entry, strongly constraining the radiant direction to the general antapex direction. Orbital integrations show that the meteoroid was injected into the near-Earth region ∼0.08 Myr ago and it never had a perihelion distance smaller than ∼0.7 AU, while other CM2 meteorites with known orbits approached the Sun closer (∼0.5 AU) and were heated to at least 100 K higher temperatures.

Chromium isotopes identify the extraterrestrial component in impactites from Dhala impact structure, India

1,2Aryavart ANAND,3Anuj Kumar SINGH,1Klaus MEZGER,3.4Jayanta Kumar PATI
Meteoritics & Planetary Science (in Press) Open Access Link to Article [doi: 10.1111/maps.139821Ó2023]
1Institut für Geologie, Universität Bern, Bern, Switzerland
2Max-Planck-Institut für Sonnensystemforschung, Göttingen, Germany
3Department of Earth and Planetary Sciences, Nehru Science Centre, University of Allahabad, Prayagraj, India
4National Centre of Experimental Mineralogy and Petrology, University of Allahabad, Prayagraj, India
Published by arrangement with John Wiley & Sons

The Dhala structure in north-central India is a confirmed complex impactstructure of Paleoproterozoic age. The presence of an extraterrestrial component inimpactites from the Dhala structure was recognized by geochemical analyses of highlysiderophile elements and Os isotopic compositions; however, the impactor type hasremained unidentified. This study uses Cr isotope systematics to identify the type ofprojectile involved in the formation of the Dhala structure. Unlike the composition ofsiderophile elements (e.g., Ni, Cr, Co, and platinum group elements) and their inter-elementratios that may get compromised due to the extreme energy generated during an impact, Crisotopes retain the distinct composition of the impactor. The distincte54Cr value of0.310.09 for a Dhala impact melt breccia sample (D6-57) indicates inheritance from animpactor originating within the non-carbonaceous reservoir, that is, the inner Solar System.Based on the Ni/Cr ratio, Os abundance, and Cr isotopic composition of the samples, theimpactor is constrained to be of ureilite type. Binary mixing calculations also indicatecontamination of the target rock by 0.1–0.3 wt% of material from a ureilite-like impactor.Together with the previously identified impactors that formed El’gygytgyn, Zhamanshin,and Lonar impact structures, the Cr isotopic compositions of the Dhala impactites arguefor a much more diverse source of the objects that collided with the Earth over itsgeological history than has been supposed previously.

Evidence for a carbon-rich Mercury from the distribution of low-reflectance material (LRM) associated with large impact basins

1Laura H. Lark,1James W. Head,1Christian Huber
Icarus (in Press) Link to Article []
1Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI, USA
Copyright Elsevier

Low-reflectance material (LRM) on the surface of Mercury is thought to be darkened by 2-7 wt.% carbon, making Mercury’s surface the most carbon-rich among the terrestrial planets, but the origin of this carbon is debated. We observe exposures of LRM within large impact basins, which naturally sample Mercury’s outer layers, to produce the first observationally constrained estimate of the absolute quantity of carbon present in Mercury’s shallow interior. We observe LRM and other spectrally distinct material associated with craters within large basins and use scaling laws to relate these observations to the stratigraphy and composition of the subsurface. We find that many large basins across Mercury’s surface have thick layers of LRM in their subsurface. Based on inferences regarding the thickness of these layers, we estimate the absolute quantity of carbon present in Mercury’s crust and upper mantle to be at least
kg, which permits evaluation of hypotheses as to its origin. This quantity rules out the hypothesis that carbon near Mercury’s surface was delivered during late accretion of carbon-rich material, with implications for the delivery of carbon and volatiles to the terrestrial planets. It is also only marginally compatible with a magma ocean origin. Therefore, if Mercury’s core and mantle equilibrated with respect to carbon, we infer that Mercury was probably carbon-saturated early in its evolution and that carbon is an abundant light element in its core, with important implications for Mercury’s thermal and geological evolution.

Laboratory synthesis, spectroscopic characteristics, and conversion relationships of five calcium sulfate double salts relevant to Mars

1Enming Ju,1Erbin Shi,1Yanqing Xin,1Haijun Cao,1Changqing Liu,1Ping Liu,1Jian Chen,1Xiaohui Fu,1Zongcheng Ling
Icarus (in Press) Link to Article []
1Shandong Provincial Key Laboratory of Optical Astronomy & Solar-Terrestrial Environment, School of Space and Physics, Institute of Space Sciences, Shandong University, Weihai 264209, China
Copyright Elsevier

Calcium sulfate veins have been found in Gale crater and Endeavour crater as indicators of Martian fluid events. The presence of mixed-cation sulfates has been suggested because a wide variety of sulfates containing different cation elements have been detected in in-situ exploration targets (e.g., soils, drilled materials, calcium sulfate veins, and sandstones). In order to establish a spectroscopic library of mixed-cation sulfates, five calcium sulfate double salts (CSDS) were successfully synthesized using high-temperature solid phase reaction and aqueous solution precipitation methods. The phase and homogeneity of these samples were confirmed by X-ray diffraction (XRD). Raman, mid-infrared (MIR), visible and near-infrared (VNIR), and Laser-induced breakdown spectrometry (LIBS) spectra were also collected to study vibrational features and elemental emission properties. All these spectral data are valuable for the mixed-cation sulfate detections by those payloads with similar spectroscopic technologies empolyed on Mars. We also studied the interrelationships among five CSDS, providing constraints for their origins in sedimentary (e.g., calcium sulfate veins) and volcanic environments on Mars.

High alumina basalts identification and their feature analysis in Mare Fecunditatis

1Ming Ma,1Jingran Chen,2Clive R. Neal,3,4Shengbo Chen,1Bingze Li,1Chenghao Han,1Peng Tian
Icarus (in Press) Link to Article []
1School of Surveying and Exploration Engineering, Jilin Jianzhu University, Changchun, China
2Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, IN 46556, USA
3School of Geo-Exploration Science and Techniques, Jilin University, Changchun, China
4Center for Excellence in Comparative Planetology, Chinese Academy of Sciences, Hefei, China
Copyright Elsevier

High alumina (HA) mare basalts play unique roles in understanding the heterogeneity of lunar mantle. Their presence was confirmed by the Apollo and Luna samples, and their remote sensing identification was implemented using HA sample FeO, TiO2 and Th concentration constraints. This study selected the surfaces with ~0.5% rock abundance as windows into HA basalts identification. The lithology of these rock pixels was first classified based on thorium maps from the Lunar Prospector and major element oxide products from Diviner data onboard the Lunar Reconnaissance Orbiter (LRO). Then, the LRO Diviner Al2O3 (~11 wt%) concentration constraint was applied in the mare basalt rock pixels across the Moon. The mare-highland mixtures were distinguished from HA basalt rocks based on the positive linear relationships between Al2O3 and Mg# in the adjacent pixels for four impact vector directions away from each candidate HA pixel. These HA basalts rock pixels identified by this study indicate that HA basalts are concentrated locally in South Pole-Aitken (SPA) basin, Schiller-Schickard region and 13 maria such as southern and northern Oceanus Procellarum, central Humorum, Tranquillitatis, Fecunditatis and Serenitatis, northern Imbrium and southern Nubium, but are seldom found in Mare Moscoviense and Orientale regions on the farside. Detailed investigations in Mare Fecunditatis found that fifteen HA basalt units or patches could be confidently identified. These HA basalts have the total area and volume of <77,658 km2 and < 54,301 km3, and the maximum depth and thickness of 1147 m and 1062 m respectively. In addition, analyses of the HA rocks indicated that the HA basalts are discontinuous and have variable thicknesses.

Autonomous Laser-Induced Breakdown Spectroscopy System for Chemical and Mineralogical Designation of Interplanetary Materials

1Stavrinos, George,1Chatzitheodoridis, Elias,1Sykioti, Olga
Studies in Computational Intelligence 1051, 177-225 Link to Article [DOI 10.1007/978-3-031-09062-2_6]
1National Observatory of Athens and National Technical University of Athens, Athens, Greece

We currently do not have a copyright agreement with this publisher and cannot display the abstract here

Nucleation experiments on a titanium-carbon system imply nonclassical formation of presolar grains

1Kimura, Yuki,2Tanaka, Kyoko K.,3,4Inatomi, Yuko,5Aktas, Coskun,5Blum, Jürgen
Science Advances 9, eadd8295 Open Access Link to Article [DOI 10.1126/sciadv.add8295]
1Institute of Low Temperature Science, Hokkaido University, Kita-19, Nishi-8, Kitaku, Sapporo, 060-0819, Japan
2Astronomical Institute, Tohoku University, 6-3 Aoba, Aoba-ku, Sendai, 985-8578, Japan
3Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo-ku, Kanagawa, Sagamihara, 252-5210, Japan
4School of Physical Sciences, SOKENDAI (Graduate University for Advanced Studies), 3-1-1 Yoshinodai, Chuo-ku, Kanagawa, Sagamihara, 252-5210, Japan
5Institut für Geophysik und Extraterrestrische Physik, Technische Universität Braunschweig, Mendelssohnstr. 3, Braunschweig, D-38106, Germany

We currently do not have a copyright agreement with this publisher and cannot display the abstract here

Thermal and shock history of Almahata Sitta meteorite inferred from structure refinement of pyroxene and Mössbauer spectroscopy of Fe-Ni metal

Meteoritics & Planetary Science (in Press) Link to Article [doi: 10.1111/maps.13988]
1Department of Applied Physics and Astronomy, University of Sharjah, Sharjah, United Arab Emirates
2Department of Physics, Sultan Qaboos University, Muscat, Oman
3College of Arts, Sciences and Information Technology, University of Khorfakkan, Khorfakkan, United Arab Emirates
4Department of Physics, University of Khartoum, Khartoum, Sudan
5Department of Earth Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
Published by arrangement with John Wiley and Sons

The crystal structures of orthopyroxene (En86.3Fs8.6Wo5.1, space group Pbca) and pigeonite (En81.7Fs8.8Wo9.5, space group P21/c) from the Almahata Sitta ureilite (fragment#051) have been refined to R1 indices of 3.10% and 2.53%, respectively, using single-crystal X-ray diffraction data. The unit formulas were calculated from electron microprobe analysis, and the occupancies at the M1 and M2 sites were refined for both pyroxenes from the single-crystal diffraction data. The results indicate a rather disordered intracrystalline Fe2+-Mg cation distribution over the M1 and M2 sites, with a closure temperature of 726(±55)°C for orthopyroxene and 704(±110)°C for pigeonite, suggesting fast cooling of these pyroxenes. The Mössbauer spectrum of the Fe-Ni metal particles of Almahata Sitta ureilite (fragment#051) is dominated by two overlapping magnetic sextets that are assigned to Fe atoms in Si-bearing kamacite, and arise from two different nearest-neighbor configurations of Fe* (=Fe+Ni) and Si atoms in the bcc structure of kamacite; (8F*, 0Si) and (7Fe*, 1Si). In addition, the spectrum shows weak absorption peaks that are attributed to the presence of small amounts of cohenite [(Fe,Ni)3C], schreibersite [(Fe,Ni)3P], and an Fe-oxide/hydroxide phase. The fast cooling of pyroxene to the closure temperature (after equilibration at ~1200°C) and the incorporation of Si in kamacite can be interpreted as due to a shock event that took place on the meteorite parent body, consistent with the proposed formation history of ureilites parent body where a fast cooling has occurred at a later stage of its formation.

Calcium isotope constraints on the origin of eucrites and diogenites: The role of magma ocean and magmatism

1,2Yongli Xue,2,3,4Jinting Kang,5,4Shiyong Liao,6Runlian Pang,2,3,4Huimin Yu,2,3,4Zifu Zhao,7Zhaofeng Zhang,8Bingkui Miao,5,3,4 Weibiao Hsu,2,3,4Fang Huang 
Earth and Planetary Science Letters 613, 118171 Link to Article []
1Key Laboratory of Gemological Design and Testing, School of Jewelry and Art Design, Wuzhou University, Wuzhou, 543002, China
2CAS Key Laboratory of Crust-Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China
3Deep Space Exploration Laboratory, University of Science and Technology of China, Hefei 230026, China
4CAS Center for Excellence in Comparative Planetology, USTC, Hefei 230026, Anhui, China
5Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210023, China
6State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China
7Research Center for Planetary Science, Chengdu University of Technology, Chengdu, 610059, China
8Institution of Meteorites and Planetary Materials Research, Key Laboratory of Planetary Geological Evolution, Guilin University of Technology, Guilin 541006, China
Copyright Elsevier

Howardite-Eucrite-Diogenite (HED) meteorites represent a large suit of crustal and sub-crustal rocks from the Vesta. This work presents systematic examination of the Ca isotope data on multiple varieties of HED meteorites for a better understanding of the magmatic evolution of the Vesta. Falls and finds possess similar Ca isotope compositions, and no correlation is observed between �44/40Ca and (Sr/Eu*)n, indicating that terrestrial weathering effect on Ca isotopes is insubstantial. According to the data in literature, the inner solar system may have a homogeneous �44/40Ca and the average of inner solar system bodies (0.97±0.03‰) can approximate the composition of bulk silicate Vesta (BSV). Basaltic eucrites define a cluster in �44/40Ca (0.95±0.07‰, 2SD, N=15) that is higher than the terrestrial mid-ocean ridge basalts (∼0.85‰). Combined with partial melting and magma ocean differentiation modeling, the Ca isotope signatures suggest that eucrites represent the residual melts evolved from a magma ocean formed by primordial Vesta’s moderate-to-high degree melting (20-100%). Diogenites have distinguishingly higher �44/40Ca (1.18±0.15‰, 2SD, N=7) than the basaltic eucrites, which displays a negative correlation with the 1000×Lu/Ti ratio and a positive correlation with 1/Ca. However, magma ocean crystallization can only explain diogenites with �44/40Ca higher than 1.17‰, suggesting that diogenites have complicated petrogenesis and are not necessarily cogenetic with eucrites. Diogenites with �44/40Ca<1.17‰ may result from magma-ocean-cumulate partial melts intruding the eucritic crust. Mixing models suggest that the eucritic component in these diogenites may be less than 10%. Two howardites have lower �44/40Ca of 0.80±0.04‰ and 0.86±0.05‰ than eucrites and diogenites. This signature may reflect the addition of carbonaceous chondritic materials due to impact brecciation.