Nanophase Iron Particles Derived From Fayalitic Olivine Decomposition in Chang'E‐5 Lunar Soil: Implications for Thermal Effects During Impacts

Guo, Zhuang; Li, Chen; Li, Yang; Wen, Yuanyun; Tai, Kairui; Li, Xiongyao; Liu, Jianzhong

doi:10.1029/2021gl097323

Cited by 35 publications

(7 citation statements)

References 37 publications

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“…A comparison of these features is presented in Figure 23 and Figure S3 in Supporting Information . Micro‐probe analyses for such np‐Fe 0 features formed on Chang’E‐5 soil mineral grains lend support to the interpretation that they were formed due to impact‐induced thermal alterations (i.e., disproportionation reaction and/or decomposition) in different Fe‐bearing minerals (Guo et al., 2022; R. Li, Guo, Li, Xia, et al., 2022; Mo et al., 2022). However, the morphology and size‐frequency distribution of the iron‐rich mound on Chang'E‐5 glass particles are both different from iron‐rich mounds produced by flash heating, suggesting that the iron‐rich mounds on the Chang’E‐5 glass particles were not obviously reduced from the solid glass by single or repeated impact heating.…”

Section: Discussionmentioning

confidence: 76%

“…A comparison of these features is presented in Figure 23 and Figure S3 in Supporting Information S1. Micro-probe analyses for such np-Fe 0 features formed on Chang'E-5 soil mineral grains lend support to the interpretation that they were formed due to impact-induced thermal alterations (i.e., disproportionation reaction and/or decomposition) in different Fe-bearing minerals (Guo et al, 2022;R. Li, Guo, Li, Xia, et al, 2022;Mo et al, 2022).…”

Section: Formation Mechanism Of the Protruded Microstructuresmentioning

confidence: 77%

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Intricate Regolith Reworking Processes Revealed by Microstructures on Lunar Impact Glasses

Pan

Yang

et al. 2022

JGR Planets

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Glasses cooled from impact melt and vapor are a common component in lunar regolith, carrying important information about protolith composition, regolith formation, and impact flux on the Moon. Interpretations, however, are frequently challenged due to widespread ambiguity in determining their provenances. Regolith samples returned by China's Chang'E-5 mission provide a unique opportunity to study the microscopic mechanism of regolith reworking on the Moon, because as evidenced by the coherent radioisotope ages and petrographic characteristics of basaltic clasts in the regolith, the Chang'E-5 regolith was mainly evolved from local mare materials, containing minor exotic components. Here, we report 153 glass particles larger than 20 μm in diameters that were screened from 500 mg of Chang'E-5 regolith. Most glass particles have rotational shapes and contain structural and/or compositional heterogeneities in interiors, and geochemical analyses reveal a dominant origin as impact melt of local mare materials. Surfaces of the impact glasses are observed to have abundant protruded and dented microstructures, which are classified as different groups based on their morphology and geochemistry. Similar microstructures were observed on impact spherules collected by the Apollo and Luna missions, but those on the Chang'E-5 impact glasses were formed without substantial involvement of exotic ejecta. Microstructures such as silicate melt pancakes that frequently exhibit flow spikes at margins, nano-phase iron-rich mounds that are arranged with semi-equidistant spaces in curves and patches, spatially clustered microcraters that are indicative of secondary impacts, and blunt linear scratches with terminal particles all suggest that regolith reworking mainly occurred among local materials at low speeds.Plain Language Summary Regolith particles on the Moon exhibit an abundance of small-scale surface texture or microstructures that were formed during regolith reworking. Lunar impact glasses are mainly melted from surface regolith, and microstructures on their surfaces record the history of subsequent regolith reworking. The possible contribution of exotic ejecta in regolith gardening is an interesting topic in lunar science. However, resolving this issue has been a persistent difficulty by both remote observations and sample analyses. China's Chang'E-5 mission returned regolith samples from one of the youngest mare units on the Moon, and earlier sample analyses revealed little exotic components. In 500 mg of Chang'E-5 regolith, we handpicked 153 glass particles that are larger than 20 μm. Most of the particles are heterogeneous impact glasses that contain voids and unmelted fragments, and geochemical analyses showed that the remaining structurally homogeneous particles were also impact glasses formed from local regolith. Based on high-resolution microscopic imaging and elemental mapping, we recognized and classified the abundant protruded and dented microstructures on the glass particles. Morphology and crosscutting relationship of t...

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Section: Discussionmentioning

confidence: 76%

Section: Formation Mechanism Of the Protruded Microstructuresmentioning

confidence: 77%

Intricate Regolith Reworking Processes Revealed by Microstructures on Lunar Impact Glasses

Pan

Yang

et al. 2022

JGR Planets

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“…Recent transmission electron microscope characterization 41 of CE-5 Fe-rich olivine rims suggests that Fe 0 particles in CE-5 samples are distinct from Apollo and Luna soil samples and were produced by olivine (especially fayalite) decomposition due to impact-induced heating processes. Irregular Fe 0 particles (with a length up to 300 nm) were also observed in the iron sulfide from CE-5 soil samples 42 .…”

Section: Discussionmentioning

confidence: 99%

Mature lunar soils from Fe-rich and young mare basalts in the Chang’e-5 regolith samples

Chen²,

Ling³

et al. 2022

Nat Astron

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“…The impacts of meteorite and micrometeorite are also important processes on the lunar surface. However, the rims formed from vapor deposition following meteoroid impacts can be distinguished by TEM and EDS results, which exhibit a significant difference in composition from the underlying layers 45 . Even small amounts of insignificant vapor deposition in the reflection IR and NanoSIMS measurement areas do not affect the results of water content.…”

Section: Methodsmentioning

confidence: 99%

Chang’E-5 samples reveal high water content in lunar minerals

Zhou

Tang

et al. 2022

Nat Commun

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The formation and distribution of lunar surficial water remains ambiguous. Here, we show the prominence of water (OH/H2O) attributed to solar wind implantation on the uppermost surface of olivine, plagioclase, and pyroxene grains from Chang’E-5 samples. The results of spectral and microstructural analyses indicate that solar wind-derived water is affected by exposure time, crystal structure, and mineral composition. Our estimate of a minimum of 170 ppm water content in lunar soils in the Chang’E-5 region is consistent with that reported by the Moon Minerology Mapper and Chang’E-5 lander. By comparing with remote sensing data and through lunar soil maturity analysis, the amount of water in Chang’E-5 provides a reference for the distribution of surficial water in middle latitude of the Moon. We conclude that minerals in lunar soils are important reservoirs of water, and formation and retention of water originating from solar wind occurs on airless bodies.

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Nanophase Iron Particles Derived From Fayalitic Olivine Decomposition in Chang'E‐5 Lunar Soil: Implications for Thermal Effects During Impacts

Cited by 35 publications

References 37 publications

Intricate Regolith Reworking Processes Revealed by Microstructures on Lunar Impact Glasses

Intricate Regolith Reworking Processes Revealed by Microstructures on Lunar Impact Glasses

Mature lunar soils from Fe-rich and young mare basalts in the Chang’e-5 regolith samples

Chang’E-5 samples reveal high water content in lunar minerals

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