Elemental composition and physical characteristics of the massive meteorite of the Saudi empty quarter

1,2AlSalhi M.S.,2Masilamani V.,3Alarifi N.,1,2Aslam Farooq W.,1,2Atif M.,1Ramay S.,1Saeed Althobaiti H.,4Anwar S.,3Elkhedr I.,3Abuamarah B.A.
Journal of King Saud University 33, 101341 Link to Article [DOI
10.1016/j.jksus.2021.101341]
1Physics and Astronomy Department, College of Science, King Saud University, Riyadh, Saudi Arabia
2Research Chair for Laser Diagnosis of Cancer, King Saud University, Riyadh, Saudi Arabia
3Department of Geology and Geophysics, College of Science King Saud University, Riyadh, Saudi Arabia
4Industrial Engineering Department, College of Engineering, King Saud University, P.O. Box 800, Riyadh, 11421, Saudi Arabia

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Continuous microfluidic solvent extraction of cobalt from mimicked and real asteroid leaching solutions

1,2Wouters M.,1Rahman S.,3Myamoto H.,1,4Tran N.N.,1,5Hessel V.
Separation and Purification Technology 260, 118238 Link to Article [DOI
10.1016/j.seppur.2020.118238]
1School of Chemical Engineering and Advanced Materials, University of Adelaide, Australia
2Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Netherlands
3Department of Systems Innovation, The University of Tokyo, Japan
4Department of Chemical Engineering, Can Tho University, Viet Nam
5School of Engineering, University of Warwick, United Kingdom

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Polycyclic aromatic hydrocarbons in the Mukundpura (CM2) Chondrite

1Kalpana M.S.,1Babu E.V.S.S.K.,2Mani D.,3Tripathi R.P.,4Bhandari N.
Planetary and Space Science 198, 105177 Link to Article [DOI
10.1016/j.pss.2021.105177]
1National Geophysical Research Institute (Council of Scientific and Industrial Research), Hyderabad, 500007, India
2Centre for Earth, Ocean and Atmospheric Sciences (CEOAS), University of Hyderabad, Gachibowli, Hyderabad, 500046, India
378, BGKT Extension, Jodhpur, 342005, India
4Science and Spirituality Research Institute, Navrangpura, Ahmedabad, 380009, India

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Asteroid break-ups and meteorite delivery to Earth the past 500 million years

1Fredrik Terfelt,1,2Birger Schmitz
Proceedings of the National Academy of Sciences of teh United States of America 118, e2020977118 Link to Article [https://doi.org/10.1073/pnas.2020977118]
1Astrogeobiology Laboratory, Department of Physics, Lund University, 221 00 Lund, Sweden;
2Robert A. Pritzker Center for Meteoritics and Polar Studies, Negaunee Integrative Research Center, Field Museum of Natural History, Chicago, IL 60605

The meteoritic material falling on Earth is believed to derive from large break-up or cratering events in the asteroid belt. The flux of extraterrestrial material would then vary in accordance with the timing of such asteroid family-forming events. In order to validate this, we investigated marine sediments representing 15 time-windows in the Phanerozoic for content of micrometeoritic relict chrome-spinel grains (>32 μm). We compare these data with the timing of the 15 largest break-up events involving chrome-spinel–bearing asteroids (S- and V-types). Unexpectedly, our Phanerozoic time windows show a stable flux dominated by ordinary chondrites similar to today’s flux. Only in the mid-Ordovician, in connection with the break-up of the L-chondrite parent body, do we observe an anomalous micrometeorite regime with a two to three orders-of-magnitude increase in the flux of L-chondritic chrome-spinel grains to Earth. This corresponds to a one order-of-magnitude excess in the number of impact craters in the mid-Ordovician following the L-chondrite break-up, the only resolvable peak in Phanerozoic cratering rates indicative of an asteroid shower. We argue that meteorites and small (<1-km-sized) asteroids impacting Earth mainly sample a very small region of orbital space in the asteroid belt. This selectiveness has been remarkably stable over the past 500 Ma.

Evidence for the protection of N-heterocycles from gamma radiation by Mars analogue minerals

1,2Gözen Ertem,3Daniel P.Glavin,4Robert P.Volpe,5Christopher P.McKay
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2021.114540]
1SETI Institute, Carl Sagan Center, Mountain View, CA 94043, USA
2Department of Atmospheric and Oceanic Science, University of Maryland, College Park, MD 20742, USA
3NASA Goddard Space Flight Center, Solar System Exploration Division, Greenbelt, MD, USA
4Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
5Space Science Division, NASA Ames Research Center, Moffett Field, CA 94035, USA
Copyright Elsevier

Organic compounds have been delivered to the surface of Mars via meteorites, comets and interplanetary dust particles for billions of years. Determining the effects of high energy radiation and galactic cosmic radiation (GCR) on these organic compounds is critical for understanding the potential for the preservation of organic molecules associated with past or present life, and where to look for possible chemical bio- signatures during future Mars missions. Understanding how these effects are attenuated by the mineral matrix and the depth at which they are buried have been challenging to determine in situ on Mars. There have been very few experimental studies on the survival of organic compounds under radiation from a gamma source under realistic conditions, and their interpretation until now has been difficult due to the lack of data for actual radiation levels on Mars. Using the in-situ data obtained by the MSL/RAD instrument to anchor the dose calculations, here we show that the N-heterocycles purine and uracil, crucial components of biochemical processes in extant living systems, mixed with calcite, anhydrite, and kaolinite as Mars analogue minerals can survive the effects of radiation with a dose corresponding to ~500,000 years on Martian surface. The extent of survival varied not only with the nature of the organic compound, but its depth from the surface. These results provide new experimental data for the degree of protection offered by the regolith, in conjunction with minerals, for organic compounds that may be present on Mars.

The trace element composition of chondrule constituents: Implications for sample return methodologies and the chondrule silicate reservoir

1Tak Kunihiro,1Tsutomu Ota,1Masahiro Yamanaka,1Christian Potiszil,1Eizo Nakamura
Meteoritics & Planatary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13665]
1The Pheasant Memorial Laboratory, Institute for Planetary Materials, Okayama University, Yamada 827, Misasa, Tottori, 682-0193 Japan
Published by arrangemment with John Wiley & Sons

Sample return missions represent great opportunities to study terrestrially uncontaminated solar system materials. However, the size of returned samples will be limited, and thus, it is necessary to understand the most appropriate techniques to apply. Accordingly, the sensitivity of laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) and secondary ion mass spectrometry (SIMS) was compared through the analyses of trace elements in reference materials and the Allende CV3 chondrite. While the SIMS method was found to be more sensitive than the laser method toward all elements of interest, the LA-ICPMS appears to be more suitable in terms of precision for certain elements. Using both analytical techniques, we measured chemical composition of an Allende chondrule and its igneous rim. These data were used to understand the nature of the reservoir that interacted with the host chondrule during formation of its igneous rim. We find that the igneous rim is enriched in silica, alkalis, and rare earth elements compared to the host chondrule. We suggest that the igneous rim could be explained by melting of a mixture of the chondrule-like and REE-enriched CAI-like precursors that accreted on the surface of the host chondrule followed by gas-melt interaction with a silica- and alkali-rich gas. Alternatively, these observations could be interpreted as a result of interaction between the chondrule and the melt resulting from partial melting of a pre-existing planetesimal in the early stages of its differentiation.

In-situ U-Pb dating of Ries Crater lacustrine carbonates (Miocene, South-West Germany): Implications for continental carbonate chronostratigraphy

1,2,3,4Damaris Montano,1,5Marta Gasparrini,2,3Axel Gerdes,5Giovanna Della Porta,2,3Richard Albert
Earth and Planetary Science Letters 568, 117011 Link to Article [https://doi.org/10.1016/j.epsl.2021.117011]
1IFP Energies nouvelles, 1-4 avenue de Bois-Préau, 92852, Rueil-Malmaison, France
2Institut für Geowissenschaften, Goethe University Frankfurt, Altenhöferallee 1, 60438 Frankfurt am Main, Germany
3Frankfurt Isotope and Element Research Center (FIERCE), Goethe University Frankfurt, Frankfurt am Main, Germany
4Sorbonne Université; ED 398 – GRNE, 4, place Jussieu, 75252 Paris, France
5Università degli Studi di Milano; Dipartimento di Scienze della Terra “Ardito Desio”, via Mangiagalli 34, 20133 Milan, Italy
Copyright Elsevier

The Nördlinger Ries Crater lacustrine basin (South-West Germany), formed by a meteorite impact in the Miocene (Langhian; ∼14.9 Ma), offers a well-established geological framework to understand the strengths and limitations of U-Pb LA-ICPMS (in situ Laser Ablation-Inductively Coupled Plasma Mass Spectrometry) geochronology as chronostratigraphic tool for lacustrine (and more broadly continental) carbonates. The post-impact deposits include siliciclastic basinal facies at the lake centre and carbonate facies at the lake margins, coevally deposited in a time window of >1.2 and <2 Ma. Depositional and diagenetic carbonate phases (micrites and calcite cements) were investigated from three marginal carbonate facies (Hainsfarth bioherm, Adlersberg bioherm and Wallerstein mound). Petrography combined with C and O stable isotope analyses indicate that most depositional and early diagenetic carbonates preserved pristine geochemical compositions and thus the U-Pb system should reflect the timing of original precipitation. In total, 22 U-Pb ages were obtained on 10 different carbonate phases from five samples. The reproducibility and accuracy of the U-Pb (LA-ICPMS) method were estimated to be down to 1.5% based on repeated analyses of a secondary standard (speleothem calcite ASH-15d) and propagated to the obtained ages. Micrites from the Hainsfarth, Adlersberg and Wallerstein facies yielded ages of 13.90 ± 0.25, 14.14 ± 0.20 and 14.33 ± 0.27 Ma, respectively, which overlap within uncertainties, and are consistent with the weighted average age of 14.30 ± 0.20 Ma obtained from all the preserved depositional and early diagenetic phases. Data indicate that sedimentation started shortly after the impact and persisted for >1.2 and <2 Ma, in agreement with previous constraints from literature, therefore validating the accuracy of the applied method. Later calcite cements were dated at 13.2 ± 1.1 (), 10.2 ± 2.7 and 9.51 ± 0.77 Ma, implying multiple post-depositional fluid events. This study demonstrates the great potential of the U-Pb method for chronostratigraphy in continental systems, where correlations between time-equivalent lateral facies are often out of reach. In Miocene deposits the method yields a time resolution within the 3rd order depositional sequences (0.5–5 Ma).

Recovery of meteorites using an autonomous drone and machine learning

1Robert I. Citron,2,3Peter Jenniskens,4Christopher Watkins,5Sravanthi Sinha,6Amar Shah,7Chedy Raissi,8Hadrien Devillepoix,2Jim Albers
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13663]
1Department of Earth and Planetary Sciences, University of California, Davis, Davis, California, 95616 USA
2SETI Institute, Mountain View, California, 94043 USA
3NASA Ames Research Center, Moffett Field, California, 94035 USA
4Scientific Computing, Commonwealth Scientific and Industrial Research Organisation, Clayton, Victoria, 3181 Australia
5Holberton School of Software Engineering, San Francisco, California, 94111 USA
6Department of Engineering, Computational and Biological Learning, Cambridge University, Cambridge, CB2 1PZ UK
7Institut National de Recherche en Informatique et en Automatique, Villers-lès-Nancy, 54506 France
8Space Science & Technology Centre, School of Earth and Planetary Sciences, Curtin University, GPO Box U1987, Perth, Western Australia, 6845 Australia
Published by arrangement with John Wiley & Sons

The recovery of freshly fallen meteorites from tracked and triangulated meteors is critical to determining their source asteroid families. Even though our ability to locate meteorite falls continues to improve, the recovery of meteorites remains a challenge due to large search areas with terrain and vegetation obscuration. To improve the efficiency of meteorite recovery, we have tested the hypothesis that meteorites can be located using machine learning techniques and an autonomous drone. To locate meteorites autonomously, a quadcopter drone first conducts a grid survey acquiring top-down images of the strewn field from a low altitude. The drone-acquired images are then analyzed using a machine learning classifier to identify meteorite candidates for follow-up examination. Here, we describe a proof-of-concept meteorite classifier that deploys off-line a combination of different convolution neural networks to recognize meteorites from images taken by drones in the field. The system was implemented in a conceptual drone setup and tested in the suspected strewn field of a recent meteorite fall near Walker Lake, Nevada.

An evolutionary condensation sequence revealed by mineralogically-distinct nodules in fine-grained, spinel-rich inclusions from CV3 chondrites: Implications for the genetic links between different types of non-igneous refractory inclusions

1Shaofan Che,1Adrian J.Brearley
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2021.05.055]
1Department of Earth and Planetary Sciences, MSC03-2040, University of New Mexico, Albuquerque, NM 87131-0001, USA
Copyright Elsevier

Fine-grained, spinel-rich inclusions (FGIs) are abundant in CV3 chondrites and exhibit textures and compositions that are consistent with a condensation origin. We have conducted a systematic investigation of FGIs from two reduced CV3 chondrites, Leoville and Efremovka, which has revealed a number of microscale variations in the primary mineralogies and textures of nodules, and provided further insights into the origins of FGIs. Nodules in individual FGIs vary in size and exhibit variations in their mineralogical zonation, resulting in significant heterogeneity within each FGI. In individual FGIs, nodules with a small size (typically <10 μm) commonly form clusters, whereas larger nodules (often >20 μm) are either embedded in the mass of small nodules or occur as shells surrounding clusters of small nodules. The size difference is associated with a difference in mineralogy: small nodules typically contain single or a few spinel/melilite grains as cores, while the spinel/melilite cores of large nodules are polycrystalline and more compact. Transmission Electron Microscope observations show that the nodules have complex microstructures, including the presence of fine-grained spinel, the close association of fine-grained Al-Ti-diopside with spinel, and a crystallographic orientation relationship between adjacent clinoenstatite and diopside grains.

Our microstructural observations indicate that disequilibrium condensation played an important role in the formation of FGIs, consistent with some previous studies. Specifically, the presence of spinel-cored and melilite-dominant nodules, as well as the different occurrences of spinel (in the cores and on the periphery), suggest that formation of these nodules occurred under disequilibrium conditions, which may be caused by physical isolation of condensates.

Nodules in FGIs show textural and compositional similarities with other types of non-igneous CAIs: hibonite-spinel inclusions and fluffy Type A CAIs. We suggest that mineralogically-distinct nodules are micrometer-sized counterparts of different types of non-igneous CAIs and record an evolutionary condensation sequence in the solar nebula. It is likely that different nodules in individual FGIs formed in the same gaseous reservoir, but at different times. The mechanism of physical isolation of condensates probably controlled the accretion behavior of nodules with different mineralogies and sizes, resulting in the observed distribution patterns of nodules. On the other hand, some mineralogically-zoned FGIs, with a Mg-rich core and a Ca-rich mantle, can be better explained by condensation, followed by transport of the inclusions to a different region of the protoplanetary disk.

Tracing the origin and core formation of the enstatite achondrite parent bodies using Cr isotopes

1,3Ke Zhu(朱柯),1Frédéric Moynier,2Martin Schiller,3Harry Becker,4Jean-Alix Barrat,1,2Martin Bizzarro
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2021.05.053]
1Université de Paris, Institut de Physique du Globe de Paris, CNRS, 75005, Paris France
2Centre for Star and Planet Formation, Globe Institute, University of Copenhagen, Øster Voldgade 5–7, Copenhagen DK-1350, Denmark
3Freie Universität Berlin, Institut für Geologische Wissenschaften, Malteserstr. 74-100, 12249 Berlin, Germany
4Univ. Brest, CNRS, UMR 6539 (Laboratoire des Sciences de l’Environnement Marin), LIA BeBEST, Institut Universitaire Européen de la Mer (IUEM), Place Nicolas Copernic, 29280 Plouzané, France
Copyright Elsevier

Enstatite achondrites (including aubrites) are the only differentiated meteorites that have similar isotope compositions to the Earth-Moon system for most of the elements. However, the origin and differentiation of enstatite achondrites and their parent bodies remain poorly understood. Here, we report high-precision mass-independent and mass-dependent Cr isotope data for 10 enstatite achondrites, including eight aubrites, Itqiy and one enstatite-rich clast in Almahatta Sitta, to further constrain the origin and evolution of their parent bodies. The ε54Cr (per 10,000 deviation of the mass bias corrected 54Cr/52Cr ratio from a terrestrial standard) systematics define three groups: main-group aubrites with ε54Cr = 0.06 ± 0.12 (2SD, N =7) that is similar to the enstatite chondrites and the Earth-Moon system, Shallowater aubrite with ε54Cr = -0.12 ± 0.04 and Itqiy-type meteorites with ε54Cr = -0.26 ± 0.03 (2SD, N =2). This shows that there were at least three enstatite achondrite parent bodies in the Solar System. This is confirmed by their distinguished mass-dependent Cr isotope compositions (δ53Cr values): 0.24 ± 0.03 ‰, 0.10 ± 0.03 ‰ and -0.03± 0.03 ‰ for main-group, Shallowater and Itqiy parent bodies, respectively. Aubrites are isotopically heavier than chondrites (δ53Cr =-0.12 ± 0.04 ‰), which likely results from the formation of an isotopically light sulfur-rich core. We also obtained the abundance of the radiogenic 53Cr (produced by the radioactive decay of 53Mn, T1/2= 3.7 million years). The radiogenic ε53Cr excesses correlate with the 55Mn/52Cr ratios for aubrites (except Shallowater and Bustee) and also the Cr stable isotope compositions (δ53Cr values). We show that these correlations represent mixing lines that also hold chronological significance since they are controlled by the crystallization of sulfides and silicates, which mostly reflect the main-group aubrite parent body differentiation at 4562.5 ± 1.1 Ma (i.e., 4.8 ± 1.1 Ma after Solar System formation). Furthermore, the intercept of these lines with the ordinate axis which represent the initial ε53Cr value of main-group aubrites (0.50 ± 0.16, 2σ) is much higher than the average ε53Cr value of enstatite chondrites (0.15 ± 0.10, 2SD), suggesting an early sulfur-rich core formation that effectively increased the Mn/Cr ratio of the silicate fraction of the main-group aubrite parent body.