Laboratory IR spectroscopy of soils from Apollo 14, 15, and 16: Spectral parameters and maturity

Planetary and Space Science (in Press) Link to Article []
1Institut für Planetologie, Wilhelm-Klemm-Strasse 10, 48149, Münster, UK
2Department of Earth and Environmental Sciences, School of Natural Sciences, The University of Manchester, Manchester, M13 9PL, UK

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Milankovitch cycles in banded iron formations constrain the Earth–Moon system 2.46 billion years ago

1,2Margriet L. Lantink,3,4Joshua H. F. L. Davies,3Maria Ovtcharova,1Frederik J. Hilgen
PNAS 119, e2117146119 Link to Article []
1Department of Earth Sciences, Utrecht University, Utrecht, 3584 CB The Netherlands
2Department of Geoscience, University of Wisconsin–Madison, Madison, WI 53706.
3Department of Earth Sciences, University of Geneva, CH-1205 Geneva, Switzerland
4Département des sciences de la Terre et de l’atmosphère/Geotop, Université du Québec à Montréal, Montréal, QC H2X 3Y7, Canada

The long-term history of the Earth–Moon system as reconstructed from the geological record remains unclear when based on fossil growth bands and tidal laminations. A possibly more robust method is provided by the sedimentary record of Milankovitch cycles (climatic precession, obliquity, and orbital eccentricity), whose relative ratios in periodicity change over time as a function of a decreasing Earth spin rate and increasing lunar distance. However, for the critical older portion of Earth’s history where information on Earth–Moon dynamics is sparse, suitable sedimentary successions in which these cycles are recorded remain largely unknown, leaving this method unexplored. Here we present results of cyclostratigraphic analysis and high-precision U–Pb zircon dating of the lower Paleoproterozoic Joffre Member of the Brockman Iron Formation, NW Australia, providing evidence for Milankovitch forcing of regular lithological alternations related to Earth’s climatic precession and orbital eccentricity cycles. Combining visual and statistical tools to determine their hierarchical relation, we estimate an astronomical precession frequency of 108.6 ± 8.5 arcsec/y, corresponding to an Earth–Moon distance of 321,800 ± 6,500 km and a daylength of 16.9 ± 0.2 h at 2.46 Ga. With this robust cyclostratigraphic approach, we extend the oldest reliable datum for the lunar recession history by more than 1 billion years and provide a critical reference point for future modeling and geological investigation of Precambrian Earth–Moon system evolution.

Martian volcanism: Current state of knowledge and known unknowns

1Peter J.Mouginis-Mark,2James R.Zimbelman,3David A.Crown,4Lionel Wilson,5Tracy K.P.Gregg
Geochemisty (Chemie der Erde) (in Press) Link to Article []
1Hawai‘i Institute Geophysics and Planetology, University of Hawai‘i, Honolulu, HI 96822, United States of America
2Center for Earth and Planetary Studies, Smithsonian Institution, Washington, DC 20560, United States of America
3Planetary Science Institute, Tucson, AZ 85719, United States of America
4Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, United Kingdom
5Department of Geology, University of Buffalo, Buffalo, NY 14260, United States of America
Copyright Elsevier

Much has been discovered about volcanism on Mars over the past fifty years of space exploration. Previous reviews of these discoveries have generally focused on the volcanic constructs (e.g., Olympus Mons and the other volcanoes within the Tharsis and Elysium regions), the analysis of individual lava flows, and how volcanic activity on Mars has evolved over time. Here we focus on attributes of volcanology that have received less attention and build upon characteristics of terrestrial volcanoes to pose new questions to guide future analyses of their Martian equivalents either with existing data sets or with new types of measurements that need to be made. The remarkable lack of exposed dikes at eroded ancient volcanoes attests to an internal structure that is different from terrestrial equivalents. Enigmatic aspects of the origin of the ridged plains (commonly accepted to be volcanic but with few identifiable flow fronts and only rare vents), the style(s) of volcanism during the earliest period of Martian history (the Noachian), and the possible mode(s) of formation of the Medusae Fossae Formation are considered here. Martian meteorites have been dated and are volcanic, but they cannot be correlated with specific geographic areas, or the chronology of Mars derived from the number of superimposed impact craters. Some of these questions about Martian volcanism can be addressed with existing instrumentation, but further progress will most likely rely on the acquisition of new data sets such as high-resolution gravity data, the return of samples from known localities, the flight of a synthetic aperture imaging radar, penetrators sent to the Medusae Fossae Formation, and detailed in situ field observations of selected volcanic sites.

Volatile interactions with the lunar surface

1Paul G. Lucey et al. (>10)
Geochemistry (Chemie der Erde) 82, 125858 Open Access Link to Article []
1University of Hawaii, United States of America
Copyright Elsevier

The Moon is generally depleted in volatile elements and this depletion extends to the surface where the most abundant mineral, anorthite, features <6 ppm H2O. Presumably the other nominally anhydrous minerals that dominate the mineral composition of the global surface—olivine and pyroxene—are similarly depleted in water and other volatiles. Thus the Moon is tabula rasa for the study of volatiles introduced in the wake of its origin. Since the formation of the last major basin (Orientale), volatiles from the solar wind, from impactors of all sizes, and from volatiles expelled from the interior during volcanic eruptions have all interacted with the lunar surface, leaving a volatile record that can be used to understand the processes that enable processing, transport, sequestration, and loss of volatiles from the lunar system. Recent discoveries have shown the lunar system to be complex, featuring emerging recognition of chemistry unanticipated from the Apollo era, confounding issues regarding transport of volatiles to the lunar poles, the role of the lunar regolith as a sink for volatiles, and the potential for active volatile dynamics in the polar cold traps. While much has been learned since the overturn of the “Moon is dry” paradigm by innovative sample and spacecraft measurements, the data point to a more complex lunar volatile environment than is currently perceived.

Internal or external magma oceans in the earliest protoplanets – Perspectives from nitrogen and carbon fractionation

1,2Damanveer S.Grewal,1Johnny D.Seales,1Rajdeep Dasguptaa
Earth and Planetary Science Letters 598, 117847 Link to Article []
1Department of Earth, Environmental, and Planetary Sciences, Rice University, 6100 Main Street, MS 126, Houston, TX 77005, USA
2Division of Geological and Planetary Sciences, California Institute of Technology, 1200 E California Blvd, Pasadena, CA 91125, USA
Copyright Elsevier

Protoplanets growing within ∼1 Ma of the Solar System’s formation underwent large-scale melting due to heat released by the decay of 26Al. When the extent of protoplanetary melting approached magma ocean (MO)-like conditions, alloy melts efficiently segregated from the silicates to form metallic cores. The nature of the MO of a differentiating protoplanet, i.e., internal or external MO (IMO or EMO), not only determines the abundances of life-essential volatiles like nitrogen (N) and carbon (C) in its core and mantle reservoirs but also the timing and mechanism of volatile loss. Whether the earliest formed protoplanets had IMOs or EMOs is, however, poorly understood. Here we model equilibrium N and C partitioning between alloy and silicate melts in the absence (IMO) or presence (EMO) of vapor degassed atmospheres. Bulk N and C inventories of the protoplanets during core formation are constrained for IMOs and EMOs by comparing the predicted N and C abundances in the alloy melts from both scenarios with N and C concentrations in the parent cores of magmatic iron meteorites. Our results show that in comparison to EMOs, protoplanets having IMOs satisfy N and C contents of the parent cores with substantially lower amounts of bulk N and C present in the parent body during core formation. As the required bulk N and C contents for IMOs and EMOs are in the sub-chondritic and chondritic range, respectively, N and C fractionation models alone cannot be used to distinguish the prevalence of these two end-member differentiation regimes. A comparison of N and C abundances in chondrites with their peak metamorphic temperatures suggests that protoplanetary interiors could lose a substantial portion of their N and C inventories with increasing degrees of thermal metamorphism. Provided the thermal metamorphism induced-loss of N and C from the protoplanetary interiors prior to the onset of core formation was efficient, the earliest formed protoplanets, as predicted by previous thermo-chemical models, are more likely to have undergone IMO differentiation resulting in the formation of N- and C-poor cores and mantles overlain by N- and C-rich undifferentiated crusts.

Differentiation time scales of small rocky bodies

1Marc Monnereau,1,2Jérémy Guignard,1,3Adrien Néri,1Michael J.Toplis,1Ghylaine Quitté
Icarus (in Press) Link to Article []
1IRAP, University of Toulouse, CNRS, Toulouse, France
2ICMCB, CNRS, Université de Bordeaux, Bordeaux, France
3BGI, University of Bayreuth, Bayreuth, Germany
Copyright Elsevier

The petrologic and geochemical diversity of meteorites is a function of the bulk composition of their parent bodies, but also the result of how and when internal differentiation took place. Here we focus on this second aspect considering the two principal parameters involved: size and accretion time of the body. We discuss the interplay of the various time scales related to heating, cooling and drainage of silicate liquids. Based on two phase flow modelling in 1-D spherical geometry, we show that drainage time is proportional to two independent parameters: , the ratio of the matrix viscosity to the square of the body radius and , the ratio of the liquid viscosity to the square of the matrix grain size. We review the dependence of these properties on temperature, thermal history and degree of melting, demonstrating that they vary by several orders of magnitude during thermal evolution. These variations call into question the results of two phase flow modelling of small body differentiation that assume constant properties. For example, the idea that liquid migration was efficient enough to remove 26Al heat sources from the interior of bodies and dampen their melting (e.g. Moskovitz and Gaidos, 2011; Neumann et al., 2012) relies on percolation rates of silicate liquids overestimated by six to eight orders of magnitude. In bodies accreted during the first few million years of solar-system history, we conclude that drainage cannot prevent the occurrence of a global magma ocean. These conditions seem ideal to explain the generation of the parent-bodies of iron meteorites. A map of the different evolutionary scenarios of small bodies as a function of size and accretion time is proposed.

Quest for the Australasian impact crater: Failings of the candidate location at the Bolaven Plateau, Southern Laos

1,2Jiří Mizera
Meteoritics & Planetary Science (in Press) Link to Article []
1Nuclear Physics Institute, Czech Academy of Sciences, Řež 130, 250 68 Husinec-Řež, Czech Republic
2Institute of Rock Structure and Mechanics, Czech Academy of Sciences, V Holešovičkách 41, 182 09 Praha 8, Czech Republic
Published by arrangement with John Wiley & Sons

The quest for the parent impact structure for Australasian tektites (AAT) has remained without solution for almost a century. The present paper doubts the plausibility of the recently proposed location of the impact site at the Bolaven volcanic field in Southern Laos by showing problems with most of the presented lines of evidence. The geochemical incompatibility of the AAT composition with a mixture of weathered basalts and Mesozoic sandstones that were proposed as source materials of AAT is demonstrated by a two-component mixing calculation for major element oxides and the Nd-Sr isotopic system. Deficiency of the basaltic component as a source of Ni, Co, Cr, and 10Be in AAT and inconsistency with trends observed for O and Pb isotopes are shown. The size of the putative crater, conclusiveness of a gravity anomaly identification, signs of complete crater burial by postimpact lava flows, and identification of proximal ejecta blanket are doubted. Remarks on the shortcomings of the current consensus location of an impact site for AAT in Indochina are presented.

Nazarovite, Ni12P5, a new terrestrial and meteoritic mineral structurally related tonickelphosphide, Ni3P

Nazarovite, Ni12P5, a new terrestrial and meteoritic mineral structurally related to
nickelphosphide, Ni3P
1,2Sergey N. Britvin,1Mikhail N. Murashko,1Maria G. Krzhizhanovskaya,1Oleg S. Vereshchagin,3Yevgeny Vapnik,4Vladimir V. Shilovskikh,5Maksim S. Lozhkin,6Edita V. Obolonskaya
American Mineralogist 107, 1946-1951 Link to Article []
1Institute of Earth Sciences, St. Petersburg State University, Universitetskaya Nab. 7/9, 199034 St. Petersburg, Russia
2Kola Science Center, Russian Academy of Sciences, Fersman Str. 14, 184200 Apatity, Russia
3Department of Geological and Environmental Sciences, Ben-Gurion University of the Negev, P.O.B. 653, Beer-Sheva 84105, Israel
4Centre for Geo-Environmental Research and Modeling, St. Petersburg State University, Ulyanovskaya ul. 1, 198504 St. Petersburg, Russia
5Nanophotonics Resource Centre, St. Petersburg State University, Ulyanovskaya ul. 1, 198504 St. Petersburg, Russia
6The Mining Museum, Saint Petersburg Mining University, 2, 21st Line, 199106 St. Petersburg, Russia
Copyright: The Mineralogical Society of America

Nazarovite, Ni12P5, is a new natural phosphide discovered on Earth and in meteorites. Terrestrial
nazarovite originates from phosphide assemblages confined to pyrometamorphic suite of the Hatrurim
Formation (the Mottled Zone), the Dead Sea basin, Negev desert, Israel. Meteoritic nazarovite was
identified among Ni-rich phosphide precipitates extracted from the Marjalahti meteorite (main group
pallasite). Terrestrial mineral occurs as micrometer-sized lamella intergrown with transjordanite (Ni2P).
Meteoritic nazarovite forms chisel-like crystals up to 8 μm long. The mineral is tetragonal, space
group I4/m. The unit-cell parameters of terrestrial and meteoritic material, respectively: a 8.640(1)
and 8.6543(3), c 5.071(3), and 5.0665(2) Å, V 378.5(2), and 379.47(3) Å3, Z = 2. The crystal structure
of terrestrial nazarovite was solved and refined on the basis of X-ray single-crystal data (R1 = 0.0516),
whereas the structure of meteoritic mineral was refined by the Rietveld method using an X-ray powder
diffraction profile (RB = 0.22%). The mineral is structurally similar to phosphides of schreibersite–
nickelphosphide join, Fe3P-Ni3P. Chemical composition of nazarovite (terrestrial/meteoritic, electron
microprobe, wt%): Ni 81.87/78.59, Fe <0.2/4.10; Co <0.2/0.07, P 18.16/17.91, total 100.03/100.67, leading to the empirical formula Ni11.97P5.03 and (Ni11.43Fe0.63Co0.01)12.07P4.94, based on 17 atoms per for- mula unit. Nazarovite formation in nature, both on Earth and in meteorites, is related to the processes of Fe/Ni fractionation in solid state, at temperatures below 1100 °C.

Jadeite and related species in shocked meteorites: Limitations on inference of shock conditions

1Ioannis Baziotis,1Stamatios Xydous1Angeliki Papoutsa,2Jinping Hu,2Chi Ma,3Stephan Klemme,3Jasper Berndt,4Ludovic Ferrière,5,6Razvan Caracas,2Paul D. Asimow
American Mineralogist 107, 1868-1977Link to Article []
1Agricultural University of Athens, Natural Resources Management and Agricultural Engineering, Laboratory of Mineralogy and Geology, Iera Odos 75, 11855, Athens, Greece
2California Institute of Technology, Division of Geological and Planetary Sciences, Pasadena, California 91125, U.S.A.
3Westfälische Wilhelms‑Univ. Münster, Institut für Mineralogie, Correnstrasse 24, 48149 Münster, Germany
4Natural History Museum, Burgring 7, A‑1010, Vienna, Austria
5CNRS, Ecole Normale Supérieure de Lyon, Laboratoire de Géologie de Lyon LGLTPE UMR5276, Centre Blaise Pascal,46 allée d’Italie Lyon 69364, France
6The Center for Earth Evolution and Dynamics (CEED), University of Oslo, Blindern, Oslo, Norway
Copyright: The Mineralogical Society of America

Jadeite is frequently reported in shocked meteorites, displaying a variety of textures and grain sizes
that suggest formation by either solid‑state transformation or by crystallization from a melt. Some‑
times, jadeite has been identified solely on the basis of Raman spectra. Here we argue that additional
characterization is needed to confidently identify jadeite and distinguish it from related species. Based
on chemical and spectral analysis of three new occurrences, complemented by first-principles calcula‑
tions, we show that related pyroxenes in the chemical space (Na)M2(Al)M1(Si2)TO6–(Ca)M2(Al)M1(AlSi)
TO6–()M2(Si)M1(Si2)TO6 with up to 2.25 atoms Si per formula unit have spectral features similar to
jadeite. However, their distinct stability fields (if any) and synthesis pathways, considered together
with textural constraints, have different implications for precursor phases and estimates of impactor
size, encounter velocity, and crater diameter. A reassessment of reported jadeite occurrences casts a
new light on many previous conclusions about the shock histories preserved in particular meteorites

An olivine cumulate outcrop on the floor of Jezero crater, Mars

1Y.Liu et al. (>10)
Science 377, 1513-1519 Link to Article [DOI: 10.1126/science.abo2756]
1Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA.
Reprinted with permission of AAAS

The geological units on the floor of Jezero crater, Mars, are part of a wider regional stratigraphy of olivine-rich rocks, which extends well beyond the crater. We investigated the petrology of olivine and carbonate-bearing rocks of the Séítah formation in the floor of Jezero. Using multispectral images and x-ray fluorescence data, acquired by the Perseverance rover, we performed a petrographic analysis of the Bastide and Brac outcrops within this unit. We found that these outcrops are composed of igneous rock, moderately altered by aqueous fluid. The igneous rocks are mainly made of coarse-grained olivine, similar to some martian meteorites. We interpret them as an olivine cumulate, formed by settling and enrichment of olivine through multistage cooling of a thick magma body.