Article
Astronomy & Astrophysics
J. A. Kegerreis, S. Ruiz-Bonilla, V. R. Eke, R. J. Massey, T. D. Sandnes, L. F. A. Teodoro
Summary: Traditionally, the Moon is believed to have formed from debris ejected by a giant impact on early Earth. However, the details of the impact scenarios are debated, and models struggle to explain the isotopic compositions of Earth and lunar rocks as well as the system's angular momentum. A high-resolution simulation suggests that giant impacts can place a satellite with similar mass and iron content as the Moon into orbit outside Earth's Roche limit. Even satellites passing within the Roche limit can survive by being partially stripped and torqued onto stable orbits.
ASTROPHYSICAL JOURNAL LETTERS
(2022)
Article
Multidisciplinary Sciences
Bin Su, Di Zhang, Yi Chen, Wei Yang, Qian Mao, Xian-Hua Li, Fu-Yuan Wu
Summary: The lunar basalts returned by the Chang'E-5 mission provide new insights into the extended duration of lunar volcanism and its possible driving mechanisms. High-precision analyses of olivine in the basalts reveal the presence of late-stage cumulates in the lunar mantle source, which could lower the melting temperature and inhibit the partitioning of certain elements into the magma. The study suggests that the addition of easily melted components from the lunar magma ocean is a key factor in driving prolonged volcanic activity on the Moon.
Review
Astronomy & Astrophysics
Lars E. Borg, Richard W. Carlson
Summary: Defining the age of the Moon has been challenging due to the need for reliable dating of lunar samples using radiometric isotopic systems associated with planet formation. The crystallization of the magma ocean is the only event that meets this criterion, with ages around 4.35 billion years recorded in lunar rock types. This age is also observed in secondary crustal rocks, suggesting contemporaneous production during magma ocean crystallization and overturn.
ANNUAL REVIEW OF EARTH AND PLANETARY SCIENCES
(2023)
Article
Geochemistry & Geophysics
Joshua F. Snape, Alexander A. Nemchin, Tim Johnson, Stefanie Luginbuhl, Jasper Berndt, Stephan Klemme, Laura J. Morrissey, Wim van Westrenen
Summary: This study investigates the mineral-melt trace element partitioning behavior during the crystallization of the Lunar Magma Ocean (LMO) through high pressure and temperature experiments. The experimental data are compared with previous studies to establish partition coefficients for each element in evolving compositions of minerals. The calculated ratios of long-lived radiogenic isotopes in lunar basalts and evolved lithologies are consistent with predictions, except for the wide range of 238U/204Pb source ratios in basaltic lunar samples. It is suggested that the Moon experienced significant volatile loss towards the end of LMO crystallization, leading to the observed U-Pb fractionation.
GEOCHIMICA ET COSMOCHIMICA ACTA
(2022)
Article
Geochemistry & Geophysics
Dian Ji, Nicholas Dygert
Summary: Plagioclase in lunar anorthositic crust has unusual rare earth element (REE) patterns and Eu abundances that cannot be explained by the solidification of lunar magma ocean (LMO). Subsequent geological processes, such as subsolidus reequilibration after the addition of a minor KREEPy component, can reproduce the REE variations in natural samples. Monte-Carlo simulations suggest that the Moon has a light-REE depleted bulk composition. A post-LMO serial processing model is proposed to explain the petrological, geochronological, and isotopic characteristics of lunar anorthosites and contemporaneous magmatism. Furthermore, it is hypothesized that Earth underwent early differentiation prior to the giant impact event that formed the Moon.
EARTH AND PLANETARY SCIENCE LETTERS
(2023)
Article
Geochemistry & Geophysics
T. E. Johnson, L. J. Morrissey, A. A. Nemchin, N. J. Gardiner, J. F. Snape
Summary: Despite decades of research on the formation and evolution of the Moon, many questions still remain unanswered. Recent thermodynamic models have provided detailed constraints on the compositional, mineralogical, and density structure of the lunar interior, laying the foundation for future research on the origin and evolution of the Moon.
EARTH AND PLANETARY SCIENCE LETTERS
(2021)
Article
Geochemistry & Geophysics
Jie-Jun Jing, Yanhao Lin, Jurrien S. Knibbe, Wim van Westrenen
Summary: High-pressure, high-temperature experiments and numerical modeling have revealed the presence of stable garnet in the deep lunar mantle, which has important implications for lunar magma ocean crystallization and crust formation. The presence of garnet reduces the aluminum oxide content in the residual lunar magma ocean and affects the fractionation of rare earth elements. Additionally, the presence of garnet delays the saturation of plagioclase, resulting in a thinner lunar crust.
EARTH AND PLANETARY SCIENCE LETTERS
(2022)
Article
Multidisciplinary Sciences
Daniel P. Moriarty, Nick Dygert, Sarah N. Valencia, Ryan N. Watkins, Noah E. Petro
Summary: The lunar surface holds ancient and well-preserved records of Solar System history and planetary evolution processes. There is debate among scientists about the lithologies of the upper lunar mantle and where they may be exposed on the surface. By reviewing dynamical models and recent data, researchers are assessing candidate lithologies and their implications for lunar evolution.
NATURE COMMUNICATIONS
(2021)
Article
Geochemistry & Geophysics
M. M. Hirschmann
Summary: The mantles of Earth and Mars are more oxidized than expected, likely due to high pressure equilibration of silicate-alloy generating more ferric iron.
GEOCHIMICA ET COSMOCHIMICA ACTA
(2022)
Article
Geochemistry & Geophysics
Kaveh Pahlevan, Laura Schaefer, Linda T. Elkins-Tanton, Steven J. Desch, Peter R. Buseck
Summary: The ratio of deuterium-to-hydrogen in the Martian atmosphere suggests planetary enrichment and early hydrogen losses. The behavior of deuterium in Mars' primordial atmosphere can be explained by a model that considers water-ocean epochs and the interaction between condensing and escaping components. The findings support the notion of significant durations of chemical conditions conducive to prebiotic chemistry immediately following the crystallization of the Martian magma ocean.
EARTH AND PLANETARY SCIENCE LETTERS
(2022)
Article
Geochemistry & Geophysics
Christian Maas, Lukas Manske, Kai Wuennemann, Ulrich Hansen
Summary: Numerical experiments were conducted to study the settling of impact-delivered material in a global magma ocean, showing crucial differences in metal dispersion and settling history depending on the latitude of the impactor's target. Impacts at the poles result in limited metal dispersion and fast settling, while impacts at lower latitudes allow for higher dispersion and slower settling, potentially leading to differences in metal-silicate equilibration in localized domains of the magma ocean.
EARTH AND PLANETARY SCIENCE LETTERS
(2021)
Article
Geochemistry & Geophysics
Francis M. McCubbin, Jonathan A. Lewis, Jessica J. Barnes, Stephen M. Elardo, Jeremy W. Boyce
Summary: Through petrologic study and data analysis of apatite in eucrites, this research quantified the abundances of F, Cl, and H2O in the bulk silicate portion of asteroid 4 Vesta. The study revealed a depletion of F and H2O in BSV compared to CI chondrites, while Cl depletion in 4 Vesta was found to be greater than in samples from Earth or the Moon. Eucrites are likely formed through serial magmatism from a mantle with heterogeneous delta Cl-37 and Cl/F, and the volatile depletion and Cl-isotopic heterogeneity recorded in eucrites may be inherited from precursor materials that accreted to form 4 Vesta.
GEOCHIMICA ET COSMOCHIMICA ACTA
(2021)
Article
Astronomy & Astrophysics
Miles Timpe, Christian Reinhardt, Thomas Meier, Joachim Stadel, Ben Moore
Summary: In the leading theory of lunar formation, a collision between two planet-size objects resulted in a young Earth surrounded by a circumplanetary debris disk from which the Moon later formed. However, none of the proposed scenarios have successfully explained all the known constraints without controversial post-impact processes. To bridge this gap, researchers conducted a systematic study of simulations of potential Moon-forming impacts. The first paper focuses on pairwise impacts between nonrotating bodies, showing that a minimum initial angular momentum budget is required to generate a sufficiently massive protolunar disk. Low-velocity impacts with high impactor-to-target mass ratios are preferred to explain the Earth-Moon isotopic similarities.
ASTROPHYSICAL JOURNAL
(2023)
Article
Geochemistry & Geophysics
Xueping Yang, Pengli He, Ya-Nan Yang, Zhixue Du
Summary: Halogens are useful tracers for understanding the formation of Earth's volatiles. Through experiments, it has been found that fluorine and chlorine are not significantly fractionated during the crystallization of deep magma oceans.
GEOCHIMICA ET COSMOCHIMICA ACTA
(2023)
Article
Geochemistry & Geophysics
Max W. Schmidt, Giuliano Kraettli
Summary: This study experimentally simulates the fractional crystallization of a global lunar magma ocean and explores the resulting mineral cumulate layers, temperature distribution, and nature of the original lunar crust. The findings suggest that the original lunar crust was thicker than currently observed, indicating that post-magma ocean convection removed denser crust layers. This process led to remelting of downslumped crust in the deep lunar mantle, generating a second generation of magmatism and providing insights into the formation of lunar samples.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2022)
Article
Geochemistry & Geophysics
Zhongtian Zhang, Shun-Ichiro Karato
Summary: The study found that grain-growth kinetics of olivine is fast even in the dry deep upper mantle, with grain size controlled by pinning by other phases or dynamic recrystallization; this has a critical impact on seismic wave attenuation. The results suggest that EAGBS may be responsible for the lower shear velocity in the deep upper mantle, indicating a potential deviation from the velocity inferred from single crystal elasticity.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2021)
Article
Geochemistry & Geophysics
George Amulele, Shun-ichiro Karato, Jennifer Girard
Summary: High pressure and temperature experiments were conducted on oxide mixtures corresponding to bridgmanite stoichiometry under hydrous shallow lower mantle conditions. Melting occurred in all runs, leading to changes in element partitioning between the melt and residual solids. The study suggests that melting under hydrous lower mantle conditions may explain seismic anomalies and the presence of stishovite in the mantle.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2021)
Article
Geochemistry & Geophysics
Yu He, Lidong Dai, Duck Young Kim, Heping Li, Shun-ichiro Karato
Summary: Researchers investigated the proton conduction mechanism in hydrous olivine using ab initio calculations and found that hydrogen trapped at the Mg (or Fe) defect is more mobile than hydrogen trapped at the Si defect. At high temperature, they observed the ionization of hydrogen from cation defects leading to highly anisotropic proton conductivity along the [100] direction. This highly anisotropic conductivity explains experimental observations on olivine single crystals.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2021)
Article
Geochemistry & Geophysics
H. E. Cho, Shun-ichiro Karato
Summary: This study investigates the finite deformation of a weak inclusion embedded in a strong matrix in order to understand the possible causes for shear localization and geochemical heterogeneity in the Earth's lower mantle. The results show that finite strain leads to a significant strain weakening under simple shear deformation. The findings have important implications for understanding the lower mantle rheology and the preservation of geochemical heterogeneity and seismic anisotropy distribution.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2022)
Article
Geosciences, Multidisciplinary
Shoji Ueta, Natsuki Hosono, Ryusuke Kuroki, Yosuke Yamashiki
Summary: Debris flow is a significant natural hazard in mountain zones, and numerical simulations, particularly using the smoothed particle hydrodynamics (SPH) method, are important for evaluating their impact. While SPH has shown promise in previous studies, further validations are needed.
JOURNAL OF DISASTER RESEARCH
(2022)
Article
Geochemistry & Geophysics
Natsuki Hosono, Shun-ichiro Karato
Summary: By utilizing different types of equations of state (EoS), we investigated the role in controlling the composition of the Moon, finding that the impact of hardness on preexisting magma ocean has a greater influence compared to the EoS of solids.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2022)
Article
Geochemistry & Geophysics
Yanyao Zhang, Suyu Fu, Shun-ichiro Karato, Takuo Okuchi, Stella Chariton, Vitali B. Prakapenka, Jung-Fu Lin
Summary: Seismic studies have identified seismic scatterers with shear velocity anomalies along subducting slabs at certain depths. The post-stishovite transition in subducted mid-ocean ridge basalt has been linked to these anomalies. Experimental data on Al-bearing stishovite crystals revealed a reduction in transition pressure and shear wave velocity due to the presence of aluminum and hydrogen.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2022)
Article
Astronomy & Astrophysics
Makoto Miyoshi, Yoshiaki Kato, Junichiro Makino
Summary: We present an independent image reconstruction of M87 using public data from the Event Horizon Telescope Collaborators (EHTC). Our results differ from the image published by EHTC. Our analysis shows that the structure at 230 GHz is consistent with lower-frequency observations, the jet structure is evident at 230 GHz extending from the core, and the unresolved core reveals three bright features indicative of an initial jet. Furthermore, we suggest that the presence of ring-like structures in the EHTC result is an artifact caused by the narrow field-of-view setting and the u-v data sampling bias effect.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Michiko S. Fujii, Kohei Hattori, Long Wang, Yutaka Hirai, Jun Kumamoto, Yoshito Shimajiri, Takayuki R. Saitoh
Summary: The motion of massive stars in star clusters plays a crucial role in the formation of star clusters and H ii regions. These stars terminate star cluster formation by ionizing the surrounding gas, and the ejected stars can also contribute to the formation of holes and bubbles.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Yutaka Hirai, Timothy C. Beers, Masashi Chiba, Wako Aoki, Derek Shank, Takayuki R. Saitoh, Takashi Okamoto, Junichiro Makino
Summary: Research suggests that most highly r-process-enhanced (RPE) stars are formed in low-mass dwarf galaxies, while stars with higher metallicity may be formed in situ. These findings contribute to our understanding of the assembly history of the Milky Way and the nucleosynthesis of heavy elements.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Geochemistry & Geophysics
Lei Kang, Shun-ichiro Karato
Summary: The solubility of hydrogen in olivine and orthopyroxene under water-saturated conditions was investigated. The results showed that the solubility of hydrogen increased with pressure and temperature in both minerals. The partition coefficient of hydrogen between orthopyroxene and olivine was calculated based on these observations, and it was found to depend weakly on temperature but strongly on pressure and water fugacity. The distribution of hydrogen between the two minerals has important implications for the bulk properties of the lithosphere and asthenosphere.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2023)
Article
Multidisciplinary Sciences
Hanyong Liu, Xiaozhi Yang, Shun-ichiro Karato
Summary: High conductivity anomalies in the shallow mantle are often attributed to minor partial melt in olivine-dominated peridotites. This study provides experimental evidence that the bulk conductivity decreases with increasing olivine grain size. The amount of melt required for the observed high conductivities in the asthenosphere is larger than previously assumed, suggesting that subsolidus solid assemblages in the upper mantle may be responsible for electrical anomalies.
Article
Astronomy & Astrophysics
Yota Ishigaki, Junko Kominami, Junichiro Makino, Masaki Fujimoto, Masaki Iwasawa
Summary: The new N-body simulation code GPLUM, equipped with the (PT)-T-3 scheme, has solved the issue of appropriate cut-off radius for each particle, leading to a significant speed-up and improved scalability of the code in studying the planetary system formation process.
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN
(2021)