^1,2M. Kimura,^3,4N. Sugiura,^1,5A. Yamaguchi,³K. Ichimura
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13474]
¹National Institute of Polar Research, Tokyo, 190‐8518 Japan
²Ibaraki University, Mito, 310‐8512 Japan
³University of Tokyo, Tokyo, 113‐0033 Japan
⁴Planetary Exploration Research Center, Chiba Institute of Technology, Chiba, 275‐0016 Japan
⁵Department of Polar Science, School of Multidisciplinary Science, SOKENDAI, The Graduate University for Advanced Studies, Tokyo, 190‐8518 Japan
Published by arrangement with John Wiley & Sons

All mesosiderites previously reported were subjected to thermal metamorphism and/or partial melting on the parent body. Therefore, their primordial features have been mostly lost. Here, we report detailed petrological and mineralogical features on a mesosiderite, Northwest Africa (NWA) 1878. This meteorite comprises silicate lithology and aggregates of small spheroidal Fe‐Ni metal grains. Silicate lithology typically shows igneous texture without recrystallization features, and mainly consists of low‐Ca pyroxene and plagioclase. Pyroxenes often show normal zoning. Exsolution lamella of augite is rarely noticed and very thin in width, compared with other mesosiderites. A few magnesian olivine grains are encountered without typical corona texture around them. They are not equilibrated with pyroxene on a large scale. Plagioclase shows a wide compositional range. These results show that NWA 1878 hardly experienced thermal metamorphism, distinguished from mesosiderites of subgroups 1–4. Therefore, we propose that this is classified as subgroup 0 mesosiderite. Nevertheless, NWA 1878 was locally subjected to secondary reactions, such as weak reduction of pyroxene and Fe‐Mg diffusion between olivine and pyroxene, on the parent body.

¹M.E.I.Riebe,¹D.I.Foustoukos,¹C.M.O’D.Alexander,¹A.Steele,¹G.D.Cody,¹B.O.Mysen,¹L.R.Nittler
Earth and Planetary Science Letters 540, 116266 Link to Article [https://doi.org/10.1016/j.epsl.2020.116266]
¹Earth and Planets Laboratory, Carnegie Institution of Washington, 5241 Broad Branch Road, Washington, DC 20015, USA
Copyright Elsevier

Interplanetary dust particles (IDPs) and micrometeorites (MMs) were likely major sources of extraterrestrial organics at the surface of the early Earth. However, these particles experience heating to >500 °C for up to several seconds during atmospheric entry. In this study, we aim to understand the effects of atmospheric entry heating on the dominant organic component in IDPs and MMs by conducting flash heating experiments (4 s to 400 °C, 600 °C, 800 °C, and 1000 °C) on insoluble organic matter (IOM) extracted from the meteorite Cold Bokkeveld (CM2). For each of the experimental charges, the bulk isotopic compositions of H, N, and C were analyzed by IRMS, the H isotopic heterogeneities (occurrence of deuterium hotspots) of the samples were measured by NanoSIMS, and the functional group chemistry and ordering of the IOM was evaluated by using FTIR and Raman spectroscopy, respectively. Organic matter in particles heated to ≥600 °C during atmospheric entry experienced significant alteration. Loss of isotopically heavy, labile H and N groups results in decreases in bulk δD, N, H/C and, upon heating ≥800 °C, in N/C. The H isotopic heterogeneity was not greatly affected by flash heating to ≤600 °C, although the hotspots tended to be less isotopically anomalous in the 600 °C sample than in the 400 °C sample. However, the hotspots all but disappeared in the 800 °C sample. Loss of C=O groups occurred at 800 °C. Based on the Raman G-band characteristics, the heating resulted in increased ordering of the polyaromatic component of the IOM.

The data presented in this study show that all aspects of the composition of organic matter in IDPs and MMs are affected by atmospheric entry heating. Modelling and temperature estimates from stepwise release of He has shown that most IDPs and MMs are heated to >500 °C (Love and Brownlee, 1991; Nier and Schlutter, 1993; Joswiak et al., 2007), hence, atmospheric entry heating is expected to have altered the organic matter in most such particles.

¹O. Unsalan,²A. Bayatlı,^3,4P. Jenniskens
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13469]
¹Department of Physics, Faculty of Science, Ege University, 35100 Bornova, Izmir, Turkey
²History Department, Faculty of Letters, Trakya University, 22030 Edirne, Turkey
³SETI Institute, 189 Bernardo Ave, Mountain View, California, 94043, USA
¹NASA Ames Research Center, Moffett Field, California, 94035 USA
Published by arrangement with John Wiley & Sons

Our planet experiences falls of meteorites with different airburst and ground impact risk. Some of these meteors can survive after the atmospheric passage and fall into the ground. Although there are claims that people were hit and killed by meteorites in history, the historical records do not prove this fact so far. This issue might be due to the fact that either the manuscript was written in a language other than English or there is not enough interest in historical records. To the best of our knowledge, we show the first proof of an event ever that a meteorite hit and killed a man and left paralyzed another on August 22, 1888 in Sulaymaniyah, Iraq, based on three manuscripts written in Ottoman Turkish that were extracted from the General Directorate of State Archives of the Presidency of the Republic of Turkey. This event was also reported to Abdul Hamid II (34th sultan of the Ottoman Empire) by the governor of Sulaymaniyah. These findings suggest other historical records may still exist that describe other events that caused death and injuries by meteorites.

¹Jérôme Aléon,²Alice Aléon-Toppani,³Bernard Platevoet,³Jacques-Marie Bardintzeff,⁴Kevin D. McKeegan, ⁵François Brisset
Proceedings of the National Academy of Sciences of the United States of Americs (PNAS) (in Press) Link to Article [DOI:
https://doi.org/10.1073/pnas.1919550117]
¹Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, UMR 7590, Sorbonne Université, Museum National d’Histoire Naturelle, CNRS, Université Pierre et Marie Curie, Institut de Recherche pour le Développement, 75005 Paris, France;
²Université Paris-Saclay, CNRS, Institut d’Astrophysique Spatiale, 91405 Orsay, France;
³Université Paris-Saclay, Sciences de la Terre, Volcanologie-Planétologie, UMR CNRS 8148 Geosciences Paris Sud, F-91405 Orsay, France;
⁴Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, CA 90095-1567;
⁵Université Paris-Saclay, CNRS, Institut de Chimie Moléculaire et des Matériaux d’Orsay, 91405 Orsay Cedex, France

Recent isotopic and paleomagnetic data point to a possible connection between carbonaceous chondrites and differentiated planetary materials, suggesting the existence, perhaps ephemeral, of transitional objects with a layered structure whereby a metal-rich core is enclosed by a silicate mantle, which is itself overlain by a crust containing an outermost layer of primitive solar nebula materials. This idea has not received broad support, mostly because of a lack of samples in the meteoritic record that document incipient melting at the onset of planetary differentiation. Here, we report the discovery and the petrologic–isotopic characterization of UH154-11, a ferroan trachybasalt fragment enclosed in a Renazzo-type carbonaceous chondrite (CR). Its chemical and oxygen isotopic compositions are consistent with very-low-degree partial melting of a Vigarano-type carbonaceous chondrite (CV) from the oxidized subgroup at a depth where fluid-assisted metamorphism enhanced the Na content. Its microdoleritic texture indicates crystallization at an increasing cooling rate, such as would occur during magma ascent through a chondritic crust. This represents direct evidence of magmatic activity in a carbonaceous asteroid on the verge of differentiating and demonstrates that some primitive outer Solar System objects related to icy asteroids and comets underwent a phase of magmatic activity early in the Solar System. With its peculiar petrology, UH154-11 can be considered the long-sought first melt produced during partial differentiation of a carbonaceous chondritic planetary body, bridging a previously persistent gap in differentiation processes from icy cometary bodies to fully melted iron meteorites with isotopic affinities to carbonaceous chondrites.

¹Max Collinet,¹Timothy L. Grove
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13471]
¹Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, 02139 Massachusetts, USA
Published by arrangement with John Wiley & Sons

Ureilites are carbon‐rich ultramafic achondrites that have been heated above the silicate solidus, do not contain plagioclase, and represent the melting residues of an unknown planetesimal (i.e., the ureilite parent body, UPB). Melting residues identical to pigeonite‐olivine ureilites (representing 80% of ureilites) have been produced in batch melting experiments of chondritic materials not depleted in alkali elements relative to the Sun’s photosphere (e.g., CI, H, LL chondrites), but only in a relatively narrow range of temperature (1120 ºC–1180 ºC). However, many ureilites are thought to have formed at higher temperature (1200 ºC–1280 ºC). New experiments, described in this study, show that pigeonite can persist at higher temperature (up to 1280 ºC) when CI and LL chondrites are melted incrementally and while partial melts are progressively extracted. The melt productivity decreases dramatically after the exhaustion of plagioclase with only 5–9 wt% melt being generated between 1120 ºC and 1280 ºC. The relative proportion of pyroxene and olivine in experiments is compared to 12 ureilites, analyzed for this study, together with ureilites described in the literature to constrain the initial Mg/Si ratio of the UPB (0.98–1.05). Experiments are also used to develop a new thermometer based on the partitioning of Cr between olivine and low‐Ca pyroxene that is applicable to all ureilites. The equilibration temperature of ureilites increases with decreasing Al₂O₃ and Wo contents of pyroxene and decreasing bulk REE concentrations. The UPB melted incrementally, at different fO₂, and did not cool significantly (0 ºC–30 ºC) prior to its disruption. It remained isotopically heterogenous, but the initial concentration of major elements (SiO₂, MgO, CaO, Al₂O₃, alkali elements) was similar in the different mantle reservoirs.

¹Connor D.Hilton, ¹Richard J.Walker
Earth and Planetary Science Letters 540, 116248 Link to Article [https://doi.org/10.1016/j.epsl.2020.116248]
¹Department of Geology, University of Maryland, College Park, MD 20742, USA
Copyright Elsevier

The origin of the IAB main group (MG) iron meteorites is explored through consideration of 182W isotopic compositions, thermal modeling of 26Al decay, and mass independent (nucleosynthetic) Mo isotopic compositions of planetesimals formed in the noncarbonaceous (NC) protosolar isotopic reservoir. A refined 182W model age for the meteorites Campo del Cielo, Canyon Diablo, and Nantan suggests that the IAB-MG parent body underwent some form of metal-silicate segregation as early as 5.3 ± 0.4 Myr after calcium-aluminum rich inclusion (CAI) formation or as late as 13.8 ± 1.4 Myr after CAI formation. If melting of the IAB-MG occurred prior to 7 Myr after CAI formation, it was likely driven by 26Al decay for a parent body radius >40 km. Otherwise, additional heat from impact is required for melting metal this late in Solar System history. If melting was partially or wholly the result of internal heating, a thermal model of 26Al decay heat production constrains the accretion age of the IAB-MG parent body to ∼1.7 ± 0.4 Myr after CAI formation. If melting was, instead, dominantly caused by impact heating, thermal modeling suggests the parent body accreted more than 2 Myr after CAI formation. Comparison of Mo mass independent isotopic compositions of the IAB-MG to other NC bodies with constrained accretion ages suggests that the Mo isotopic composition of the NC reservoir changed with time, and that the IAB-MG parent body accreted between 2 to 3 Myr after CAI formation, thus requiring an origin by impact. The relationship between nucleosynthetic Mo isotopic compositions and accretion ages of planetesimals from the NC reservoir suggests that isotopic heterogeneity developed from either addition of s-process material to, or removal of coupled r-/p-process material from the NC reservoir.

^1,2Janne Blichert-Toft,³Christa Göpel,³Marc Chaussidon,^1,2F.Albarède
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2020.04.006]
¹Laboratoire de Géologie de Lyon, École Normale Supérieure de Lyon, CNRS UMR 5276, Université de Lyon, 46 Allée d’Italie, 69007 Lyon, France
²Department of Earth, Environmental and Planetary Sciences, Rice University, 6100 Main Street, Houston, TX 77005, USA
³Université de Paris, Institut de Physique du Globe de Paris, CNRS, 1 Rue Jussieu, 75005 Paris, France
Copyright Elsevier

Lead isotope compositions were measured on both single and combined chondrules from the CV3 carbonaceous chondrite Allende with the goal of determining the range of Th/U implied by the radiogenic 208Pb*/206Pb* values. All samples were aggressively acid step-leached to separate radiogenic from primordial lead. It is found that apparent Th/U varies both between individual chondrules and between the different leaching fractions of each chondrule or group of chondrules. Specifically, the apparent Th/U ratio deviates from the planetary value (3.876), varying spectacularly from 0.65 to 14.6. Variations between leachates and residues disclose the existence of internal heterogeneities, while inter-chondrule variations reveal the presence of external heterogeneities. Three main explanations for the observed Th-U fractionation that are not mutually exclusive prevail: (1) uranium species, notably UO and UO₂, coexisted in the nebular gas at high temperature, whereas Th existed exclusively as ThO₂; (2) chondrules interacted with an exotic oxidized vapor; and (3) chondrules represent melt of dust of different origins, a hypothesis dictated by the evidence of internal heterogeneity. The extent to which the measured apparent Th/U variability is due to each of these particular processes is difficult to assess, but the existence of substantial Th/U heterogeneity, especially within, but also among, single (or pooled) chondrules from the same chondrite calls for caution when Pb-Pb linear arrays, or mixing lines, are assigned isochronous significance.

^1,2James Wampler,³Mark Thiemens,³Shaobo Cheng,³Yimei Zhu,^1,2Ivan K. Schuller
Proceedings of the National Academy of Sciences of the United States of America (PNAS) (in Press) Link to Article [https://doi.org/10.1073/pnas.1918056117]
¹Department of Physics, University of California San Diego, La Jolla, CA 92093;
²Center for Advanced Nanoscience, University of California San Diego, La Jolla, CA 92093;
³Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA 92093;
⁴Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, NY 11973

Meteorites can contain a wide range of material phases due to the extreme environments found in space and are ideal candidates to search for natural superconductivity. However, meteorites are chemically inhomogeneous, and superconducting phases in them could potentially be minute, rendering detection of these phases difficult. To alleviate this difficulty, we have studied meteorite samples with the ultrasensitive magnetic field modulated microwave spectroscopy (MFMMS) technique [J. G. Ramírez, A. C. Basaran, J. de la Venta, J. Pereiro, I. K. Schuller, Rep. Prog. Phys. 77, 093902 (2014)]. Here, we report the identification of superconducting phases in two meteorites, Mundrabilla, a group IAB iron meteorite [R. Wilson, A. Cooney, Nature 213, 274–275 (1967)] and GRA 95205, a ureilite [J. N. Grossman, Meteorit. Planet. Sci. 33, A221–A239 (1998)]. MFMMS measurements detected superconducting transitions in samples from each, above 5 K. By subdividing and remeasuring individual samples, grains containing the largest superconducting fraction were isolated. The superconducting grains were then characterized with a series of complementary techniques, including vibrating-sample magnetometry (VSM), energy-dispersive X-ray spectroscopy (EDX), and numerical methods. These measurements and analysis identified the likely phases as alloys of lead, indium, and tin.

¹Jack Wisdom
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13463]
¹Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139 USA
Published by arrangement with John Wiley & Sons

In Wisdom (2017), I presented new simulations of meteorite transport from the chaotic zones associated with major resonances in the asteroid belt: the ν6 secular resonance, the 3:1 mean motion resonance with Jupiter, and the 5:2 mean motion resonance with Jupiter. I found that the observed afternoon excess (the fact that approximately twice as many meteorites fall in the afternoon as in the morning) of the ordinary chondrites is consistent with chaotic transport from the 3:1 resonance, contradicting prior reports. Here I report an additional study of the transport of meteorites from ν6 secular resonance and the 3:1 mean motion resonance. I use an improved integration algorithm, and study the evolution of more particles. I confirm that the afternoon excess of the ordinary chondrites is consistent with transport from the 3:1 resonance.

¹Lei Song,¹Jiao Xu,² Hong Tang,¹ Jiquan Liu,²Jianzhong Liu,²Xiongyao Li,¹Shuqian Fan
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2020.113810]
¹Chongqing Key Laboratory of Additive Manufacturing Technology and System, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, No.266 Fangzheng Avenue, Beibei District, Chongqing 400714, PR China
²Center for Lunar & Planetary Sciences, Institute of Geochemistry, Chinese Academy of Sciences, 99 Lincheng West Road, Guiyang 550081, PR China
Copyright Elsevier

Lunar regolith in-situ utilization receives increasing attentions due to development of lunar exploration research. The complex composition of lunar regolith leads to its complicated phase reaction and composition evolution at high temperature, whereas few studies focus on the alteration of physicochemical properties for simulated lunar regolith at high temperature. This paper focuses on physicochemical variation characteristics and magnetic transformation for high-Ti type basalt lunar regolith simulant CLRS-2 during vacuum sintering process. Importantly, the effect of heat-treatment on magnetic properties of CLRS-2 and the magnetic properties difference between high-Ti and low-Ti type basalt lunar regolith simulant have been investigated. The results would help us understand how the micro-morphology and chemical composition of ilmenite change in lunar regolith during sintering process. What can be inferred is that the ions substitution between ilmenite and other minerals or amorphous phase would occur during sintering process of lunar regolith at high temperature in vacuum, which would lead to the evaporation of Fe-containing components. Besides, the results of micro-hardness indicate that the ilmenite content difference between CLRS-1 and CLRS-2 have no influence on the micro-hardness of the sintered samples, while the density of samples and the sintering condition such as temperature have a greater influence.