Size-frequency distributions and physical properties of chondrules from x-ray computed microtomography and digital data extraction

1,2Jon M. Friedrich,1Matthiew M. Chen,1Stephanie A. Giordano,1Olivia K. Matalka,1Juliette W. Strasser,1Kirstin A. Tamucci,3Mark L. Rivers,2,4,5Denton S. Ebel
Microscopy Research & Technique (in Press) Link to Article []
1Department of Chemistry, Fordham University, Bronx, New York, USA
2Department of Earth and Planetary Sciences, American Museum of Natural History, New York, New York, USA
3Center for Advanced Radiation Sources, University of Chicago, Argonne, Illinois, USA
4Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York, USA
5Graduate Center of the City University of New York, New York, New York, USA

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

Magmatic evolution of the host magma of plutonic rocks in the Procellarum KREEP Terrane

1Shigeko Togashi,1Akihiko Tomiya,2Noriko T.Kita,1,3Yuichi Morishita
Geochimica et Cosmochimica Acta (in Press) Link to Article []
1Geological Survey of Japan, AIST, Central 7, Higashi 1-1-1, Tsukuba 305-8567, Japan
2Department of Geoscience, University of Wisconsin, Madison 1215 W. Dayton Street Madison, WI 53706-1692, USA
3Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan
Copyright Elsevier

The origin of the KREEP (K, Rare Earth Element and P)-rich component of the Mg-suite rocks of the Procellarum KREEP Terrane (PKT), one of three major lunar crustal terranes, is unclear. In an attempt to determine its origin, we estimated the composition of host magmas of plutonic rocks, including Mg-suite rocks and evolved rocks, from the PKT (PKT-host magmas) by using secondary ion mass spectrometry analyses of plagioclase. Calculated partition coefficients for Sr, Ba and Ti between plagioclase and melts, taking into account the anorthite content of plagioclase, temperature and bulk rock major-element compositions, were applied to determine parental magma compositions. The PKT-host magmas contained 160–360 ppm Sr, 520–7600 ppm Ba and 1.1–7.0 wt.% TiO2; most of them had higher Ti and Ba concentrations than KREEP basalts and high-K KREEP. We used phase relations based on the Rhyolite-MELTS algorithm to explore the evolution of the PKT-host magmas and KREEP basalts from two bulk silicate moon (BSM) starting compositions, a BSM with chondritic ratios of refractory elements, and a crustal-component-enriched BSM with non-chondritic ratios of refractory elements. We propose a three-stage evolution model. Stage-1: polybaric multi-step fractionation from a BSM magma to form ferroan anorthosite (FAN) crust and an evolved magma as the first KREEP-rich component (M0). Stage-2: assimilation and fractional crystallization (AFC) of M0, early cumulate and FAN associated with deep mantle overturn and impact events to form the PKT-host magmas, Mg-suite rocks and an evolved magma as the second KREEP-rich component (K0). Stage-3: further AFC cycles of K0, Mg-suite rocks or FAN associated with shallow mantle overturn and impact events to form KREEP basalts. This three-stage model for a crustal-component-enriched BSM with non-chondritic ratios of refractory elements (e.g., a sub-chondritic Ti/Ba ratio) reproduced the compositions of both the host magmas of FAN and the PKT-host magmas that fractionated to form the Mg-suite rocks and KREEP basalts of the PKT region. In particular, the model reproduced the high Ti and Ba contents of the PKT-host magmas we estimated from plagioclase composition. Variations of TiO2 and Ba contents (and hence Ti/Ba ratios) of the magmas were critical controls on their evolution.

Oxygen and magnesium mass-independent isotopic fractionation induced by chemical reactions in plasma

1François Robert,2Marc Chaussidon,2Adriana Gonzalez-Cano,1Smail Mostefaoui
Proceeding sof the National Academy of Sciences of the United States of America (in Press) Link to Article []
1Institut Origine et Evolution, Muséum National d’Histoire Naturelle, Sorbonne Université, IMPMC-UMR 7590 CNRS, 75005 Paris, France;
2Université de Paris, Institut de Physique du Globe de Paris, CNRS, F-75005 Paris, France

Enrichment or depletion ranging from −40 to +100% in the major isotopes 16O and 24Mg were observed experimentally in solids condensed from carbonaceous plasma composed of CO2/MgCl2/Pentanol or N2O/Pentanol for O and MgCl2/Pentanol for Mg. In NanoSims imaging, isotope effects appear as micrometer-size hotspots embedded in a carbonaceous matrix showing no isotope fractionation. For Mg, these hotspots are localized in carbonaceous grains, which show positive and negative isotopic effects so that the whole grain has a standard isotope composition. For O, no specific structure was observed at hotspot locations. These results suggest that MIF (mass-independent fractionation) effects can be induced by chemical reactions taking place in plasma. The close agreement between the slopes of the linear correlations observed between δ25Mg versus δ26Mg and between δ17O versus δ18O and the slopes calculated using the empirical MIF factor η discovered in ozone [M. H. Thiemens, J. E. Heidenreich, III. Science 219, 1073–1075; C. Janssen, J. Guenther, K. Mauersberger, D. Krankowsky. Phys. Chem. Chem. Phys. 3, 4718–4721] attests to the ubiquity of this process. Although the chemical reactants used in the present experiments cannot be directly transposed to the protosolar nebula, a similar MIF mechanism is proposed for oxygen isotopes: at high temperature, at the surface of grains, a mass-independent isotope exchange could have taken place between condensing oxides and oxygen atoms originated form the dissociation of CO or H2O gas.

Nanoscale mineralogy and organic structure in Orgueil (CI) and EET 92042 (CR) carbonaceous chondrites studied with AFM-IR spectroscopy

1Van T. H. Phan,1Rolando Rebois,1Pierre Beck,1Eric Quirico,1Lydie Bonal,2Takaaki Noguchi
Meteoritics & Planetary Science (in Press) Link to Article []
1Institut de Planétologie et d’Astrophysique de Grenoble (IPAG), Université Grenoble Alpes/CNRS-INSU, UMR 5274, Grenoble, F-38041 France
2Division of Earth and Planetary Sciences, Graduate School of Science, Kyoto University, Kitashirakawaoiwake-cho, Sakyo-ku, Kyoto, 606-8502 Japan
Published by arrangement with John Wiley & Sons

Meteorite matrices from primitive chondrites are an interplay of ingredients at the sub-µm scale, which requires analytical techniques with the nanometer spatial resolution to decipher the composition of individual components in their petrographic context. Infrared spectroscopy is an effective method that enables the probing of vibrations at the molecule atomic scale of organic and inorganic compounds but is often limited to a few micrometers in spatial resolution. To efficiently distinguish spectral signatures of the different constituents, we apply here nano-infrared spectroscopy (AFM-IR), based on the combination of infrared and atomic force microscopy, having a spatial resolution beyond the diffraction limits. Our study aims to characterize two chosen meteorite samples to investigate primitive material in terms of bulk chemistry (the CI chondrite Orgueil) and organic composition (the CR chondrite EET 92042). We confirm that this technique allows unmixing the IR signatures of organics and minerals to assess the variability of organic structure within these samples. We report an investigation of the impact of the widely used chemical HF/HCl (hydrogen fluoride/hydrochloric acid) extraction on the nature of refractory organics (insoluble organic matter [IOM]) and provide insights on the mineralogy of meteorite matrices from these two samples by comparing to reference (extra)terrestrial materials. These findings are discussed with a perspective toward understanding the impact of post-accretional aqueous alteration and thermal metamorphism on the composition of chondrites. Last, we highlight that the heterogeneity of organic matter within meteoritic materials extends down to the nanoscale, and by comparison with IOMs, oxygenated chemical groups are not affected by acid extractions.

Constraints on the formation of carbonates and low-grade metamorphic phases in the Martian crust as a function of H2O-CO2 fluids

1,2Julia Semprich,2,3Justin Filiberto,2Allan H. Treiman,1Susanne P. Schwenzer
Meteoritics & Planetary Science (in Press) Link to Article []
1AstrobiologyOU, School of Environment, Earth and Ecosystem Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA UK
2Lunar and Planetary Institute, USRA, 3600 Bay Area Blvd, Houston, Texas, 77058 USA
3Astromaterials Research and Exploration Science (ARES) Division, XI3, NASA Johnson Space Center, Houston, Texas, 77058 USA
Published by arrangement with John Wiley & Sons

Low-grade metamorphic hydrous minerals and carbonates occur in various settings on Mars and in Martian meteorites. We present constraints on the stability of prehnite, zeolites, serpentine, and carbonates by modeling the influence of H2O-CO2 fluids during low-grade metamorphism in the Martian crust using compositions of a Martian basalt and an ultramafic cumulate. In basaltic compositions with 5 wt% fluid, our models predict prehnite in less oxidized, CO2-poor conditions (≤0.44 mol kg−1 CO2) on warmer geotherms of 20 °C km−1. At fluid-saturated conditions, epidote and laumontite are replaced by quartz, calcite, chlorite, and muscovite. In ultramafic compositions with 5 wt% fluid, antigorite (serpentine) is stable at CO2-poor conditions of ≤0.33 mol kg−1, while talc forms at 0.05–0.56 mol kg−1 CO2. At fluid-saturated conditions, antigorite is replaced by talc and chlorite, and at higher X(CO2) by magnesite and quartz. Our models therefore suggest that prehnite, zeolites, and serpentine have formed in a CO2-poor environment on Mars implying that fluids during their formation either did not contain high amounts of CO2 or had degassed CO2. Carbonates and potentially talc would have formed in the presence of a CO2-bearing fluid and therefore at different alteration stages than for prehnite, zeolites, and serpentine either in the same hydrothermal event during which the fluid composition changed gradually due to cooling and precipitation or by separate and successive alteration events with fluids of different compositions.

Characterization of novel lunar highland and mare simulants for ISRU research applications

1Maxim Isachenkov,1Svyatoslav Chugunov,2Zoe Landsman,1Iskander Akhatov,2Anna Metke,1Andrey Tikhonov,1Igor Shishkovsky
Icarus (in Press) Link to Article []
1Skolkovo Institute of Science and Technology, Center for Design, Manufacturing, and Materials, 30 Bolshoy boulevard, bld, 1121205 Moscow, Russian Federation

2CLASS Exolith Lab, Florida Space Institute, 12354 Research Parkway, Orlando, FL 32826, United States of America
Copyright Elsevier

Lunar regolith is the most critical material for the in-situ resource utilization in the crewed Moon exploration missions. This natural material can be utilized for the additive manufacturing of concrete or ceramic parts on the Moon’s surface to support permanent human presence on the surface of Earth’s natural satellite. Due to the scarcity of regolith on Earth, its simulants are used in lab research to prepare the technology for Moon missions. The present study is devoted to the characterization of lunar regolith simulant material, recently developed by the University of Central Florida, that is considered as a suitable material for regolith-focused additive manufacturing technologies. This paper describes the characterization of the LHS-1 and LMS-1 simulants using XRF, XRD, SEM, EDX, DTA, TGA, UV/Vis/NIR spectroscopy, and Laser diffractometry methods to provide data on their mineral, chemical, and fractional composition, as well as, on their morphology and optical properties. The results were compared to the data of the previously developed simulants and the original lunar samples delivered by Apollo and Luna missions. It was found that LHS-1 and LMS-1 simulants well mimic the primary properties of the original lunar regolith and can be potentially used for ISRU research tasks.

A machine learning toolkit for CRISM image analysis

1Emanuele Plebani,2Bethany L.Ehlmann,2,3Ellen K.Leask,4Valerie K.Fox,1M. Murat Dundar
Icarus (in Press) Link to Article []
1Computer and Information Sciences Department, Indiana University – Purdue University, Indianapolis, 46202, IN, USA
2Div. of Geological & Planetary Sciences, California Institute of Technology, Pasadena, 91125, CA, USA
3John Hopkins University Applied Physics Laboratory, Laurel, 20723, MD, USA
4Department of Earth and Environmental Sciences, University of Minnesota, Minneapolis, 55455, MN, USA
Copyright Elsevier

Hyperspectral images collected by remote sensing have played a significant role in the discovery of aqueous alteration minerals, which in turn have important implications for our understanding of the changing habitability on Mars. Traditional spectral analyses based on summary parameters have been helpful in converting hyperspectral cubes into readily visualizable three channel maps highlighting high-level mineral composition of the Martian terrain. These maps have been used as a starting point in the search for specific mineral phases in images. Although the amount of labor needed to verify the presence of a mineral phase in an image is quite limited for phases that emerge with high abundance, manual processing becomes laborious when the task involves determining the spatial extent of detected phases or identifying small outcrops of secondary phases that appear in only a few pixels within an image. Thanks to extensive use of remote sensing data and rover expeditions, significant domain knowledge has accumulated over the years about mineral composition of several regions of interest on Mars, which allow us to collect reliable labeled data required to train machine learning algorithms. In this study we demonstrate the utility of machine learning in two essential tasks for hyperspectral data analysis: nonlinear noise removal and mineral classification. We develop a simple yet effective hierarchical Bayesian model for estimating distributions of spectral patterns and extensively validate this model for mineral classification on several test images. Our results demonstrate that machine learning can be highly effective in exposing tiny outcrops of specific phases in orbital data that are not uncovered by traditional spectral analysis. We package implemented scripts, documentation illustrating use cases, and pixel-scale training data collected from dozens of well-characterized images into a new toolkit. We hope that this new toolkit will provide advanced and effective processing tools and improve community’s ability to map compositional units in remote sensing data quickly, accurately, and at scale.

Geophysical and cosmochemical evidence for a volatile-rich Mars

Earth and Planetary Science Letters 578, 117330 Link to Article []
1Institute of Geophysics, ETH Zürich, Zürich, Switzerland
2Physik Institut, University of Zürich, Zürich, Switzerland
3Institute of Geochemistry and Petrology, ETH Zürich, Zürich, Switzerland
4Royal Observatory of Belgium, Brussels, Belgium
Copyright Elsevier

Constraints on the composition of Mars principally derive from chemical analyses of a set of Martian meteorites that rely either on determinations of their refractory element abundances or isotopic compositions. Both approaches, however, lead to models of Mars that are unable to self-consistently explain major element chemistry and match its observed geophysical properties, unless ad hoc adjustments to key parameters, namely, bulk Fe/Si ratio, core composition, and/or core size are made. Here, we combine geophysical observations, including high-quality seismic data acquired with the InSight mission, with a cosmochemical model to constrain the composition of Mars. We find that the FeO content of Mars’ mantle is 13.7±0.4 wt%, corresponding to a Mg# of 0.81±0.01. Because of the lower FeO content of the mantle, compared with previous estimates, we obtain a higher mean core density of 6150±46 kg/m3 than predicted by recent seismic observations, yet our estimate for the core radius remains consistent around 1840±10 km, corresponding to a core mass fraction of 0.250±0.005. Relying on cosmochemical constraints, volatile element behaviour, and planetary building blocks that match geophysical and isotopic signatures of Martian meteorites, we find that the liquid core is made up of 88.4±3.9 wt% Fe-Ni-Co with light elements making up the rest. To match the mean core density constraint, we predict, based on experimentally-determined thermodynamic solution models, a light element abundance in the range of ≈9 wt% S, ⩾3 wt% C, ⩽2.5 wt% O, and ⩽0.5 wt% H, supporting the notion of a volatile-rich Mars. To accumulate sufficient amounts of these volatile elements, Mars must have formed before the nebular gas dispersed and/or, relative to Earth, accreted a higher proportion of planetesimals from the outer protoplanetary disk where volatiles condensed more readily.

A temporal shift of chondrule generation from the inner to outer Solar System inferred from oxygen isotopes and Al-Mg chronology of chondrules from primitive CM and CO chondrites

1Kohei Fukuda,1,2Travis J.Tenner,3Makoto Kimura,4Naotaka Tomioka,1Guillaume Siron,4Takayuki Ushikubo,1,5Noël Chaumard,1,6Andreas T.Hertwig,1Noriko T.Kita
Geochimica et Cosmochimica Acta (in Press) Link to Article []
1WiscSIMS, Department of Geoscience, University of Wisconsin-Madison, 1215 W. Dayton St., Madison, WI 53706, USA
2Chemistry Division, Nuclear and Radiochemistry, Los Alamos National Laboratory, MSJ514, Los Alamos, NM 87545, USA
3National Institute of Polar Research, Tokyo 190-8518, Japan
4Kochi Institute for Core Sample Research, JAMSTEC, Kochi 783-8502, Japan
5Fi Group, Direction scientifique, 14 terrasse Bellini, 92800, Puteaux, France
6Institute of Earth Sciences, Heidelberg University, Im Neuenheimer Feld 236, 69120 Heidelberg, Germany
Copyright Elsevier

Deciphering the spatial and temporal evolution of chondrules allows for a better understanding of how asteroidal seeds formed, migrated, and eventually accreted into parent asteroids. Here we report high precision Al-Mg ages and oxygen three-isotope ratios of fifteen FeO-poor chondrules from the least metamorphosed Mighei-like (CM) and Ornans-like (CO) carbonaceous chondrites, Asuka 12236 (CM2.9), Dominion Range 08006 (CO3.01), and Yamato-81020 (CO3.05). This is the first report of Al-Mg ages of chondrules from the CM chondrite group. All but one of the fifteen chondrules exhibit a restricted range of inferred initial 26Al/27Al ratios, and all ratios are ≤ 6.0 × 10−6, which is systematically lower than those of the majority of ordinary chondrite (OC) chondrules. These observations indicate that the majority of chondrules in the outer Solar System were produced ≥ 2.2 Ma after the formation of Ca-Al-rich inclusions (CAIs), which postdates OC chondrule formation in the inner Solar System (≤ 2.2 Ma after CAI formation). We propose that the discrete chondrule-forming events in different disk regions reflect a time difference in growth and orbital evolution of planetesimals within the first 4 Ma of the Solar System.

One chondrule from Asuka 12236 has an age of 1.9 Ma after CAI formation and is therefore significantly older than the other fourteen chondrules, meaning this chondrule formed contemporaneously with the majority of OC chondrules. This old chondrule also exhibits 16O-depleted oxygen isotope characteristics compared to the other chondrules, suggesting a distinct formation region, probably inside the disk region relative to where the majority of CM and CO chondrules formed. Our results indicate that this old chondrule has migrated from the inner to the outer part of the protoplanetary disk within ∼1 Ma and then accreted into the CM parent asteroid >3 Ma after CAI formation, although its formation exterior to the accretion region of the CM parent asteroid and subsequent inward migration cannot be ruled out completely.

Oxygen isotope variations in Mg-rich olivines from type I chondrules in carbonaceous chondrites

1,2Guy Libourel,2Kazuhide Nagashima,3Marc Portail,2Alexander N.Krot
Geochimica et Cosmochimica Acta (in Press) Link to Article []
1Université Côte d’Azur, OCA, CNRS, Laboratoire Lagrange, Boulevard de l’Observatoire, CS 34229, 06304 Nice Cedex 4, France
2Hawai‘i Institute of Geophysics and Planetology, School of Ocean, Earth Science and Technology, University of Hawai‘i at Mānoa, Honolulu, Hawai‘i 96821, USA
3CNRS-CRHEA (Centre de Recherches sur l’Hétéro-Epitaxie et ses Applications), Université Côte d’Azur, Sophia Antipolis, Rue Bernard Grégory, 06560 Valbonne, France
Copyright Elsevier

Using high-resolution cathodoluminescence (HR-CL) panchromatic imaging for the location of high-precision oxygen three-isotope analyses by secondary ion mass-spectrometry (SIMS), this study is aimed at characterizing the oxygen-isotope variations in Mg-rich olivines (≥ Fo99) of selected type I chondrules from the Yamato (Y) -81020 CO3.05 (Ornans-type) carbonaceous chondrite. Cathodoluminescence being extremely sensitive to faint changes in CL activator/quencher concentrations (Al, Cr, Mn, Fe) allows us to describe various overlooked cycles of growth and dissolution in Mg-rich olivines, which strongly suggest an intimate relationship with their gaseous environment during their formation. The present study confirms significant Δ17O variations of ten ‰ in Mg-rich olivines but does not support the relationship previously found between Mg# [MgO/(MgO+FeO)×100, mol%] and Δ17O among type I chondrules, nor the interpretation of redox changes that has been made of it. We instead show that Mg-rich olivines in Y-81020 chondrules exhibit a prominent 16O-enriched and 16O-depleted bimodal distribution, which is considered as the most primordial signature of type I chondrules from Y-81020 and very likely other carbonaceous chondrites. This signature is interpreted as a snapshot of the early stages of a mixing occurring between two clouds/environments in which chondrules formed and evolved by gas-melt interaction and mixed according to hydrodynamical instabilities imposed by the process responsible for the mixing. As far as this study allows, O-isotope variations of Mg-rich olivines seems to account for large scale dynamical instabilities while chemical variations highlighted by HR-CL (dissolution/growth) bear witness of smaller scale instabilities very likely occurring in the immediate vicinity of the chondrules. Without being able to decide on plausible astrophysical settings yet, we note however that processes like disruptive and vaporizing collisions between planetesimals offer a range of processes and physicochemical conditions, e.g., expansion, decompression, dynamical instabilities, that deserve to be explored in more detail, some of which resembling those highlighted in this study, e.g., gas-melt interaction, partial pressure fluctuations, heterogeneous materials, gas mixing.