The newly identified Jinlin crater in southern China lies on a hillside covered by a thick granite weathering crust.It appears as a slightly elliptical bowl-shaped depression with a diameter of 820-900 m.The structure...The newly identified Jinlin crater in southern China lies on a hillside covered by a thick granite weathering crust.It appears as a slightly elliptical bowl-shaped depression with a diameter of 820-900 m.The structure is a tilted impact crater,showing a maximum rim height difference of about 200 m and an apparent depth of 90 m.The crater rim is composed mainly of granite weathered soil and a small amount of granite fragments,while the bottom of the crater is filled with the same mixture of granite weathered soil and granite fragments.Planar deformation features in quartz grains from the rock fragments of the crater provide decisive evidence for its impact origin.The impact event is inferred to have taken place during the Holocene.展开更多
CB chondrite is a class of meteorite rich in metal composition,and its characteristics are obviously different from other chondrite groups.These meteorites are distinguished by their content of up to 60% to 70%FeNi me...CB chondrite is a class of meteorite rich in metal composition,and its characteristics are obviously different from other chondrite groups.These meteorites are distinguished by their content of up to 60% to 70%FeNi metals and sulfides,in addition to their extreme lack of volatile and moderately volatile elements,less refractory inclusions,and almost no fine-grained matrix.Sierra Gorda 013(SG013)is a metal-rich chondritic meteorite of the CBa type.It has two different lithologies within SG 013:Lithology 1and Lithology 2.Lithology 1 is an anomalous CBa chondrite containing chromite-pyroxene complex assemblage,whereas Lithology 2 is featured by recrystallization with small chondrules and contains much less iron nickel metal than Lithology 1.Although the two lithologies have essentially the same oxygen isotope composition,their structures are different from each other,suggesting that they probably underwent distinct formation and evolution processes from common precursors.In this study,the mineralogy of SG013 chondrites is studied by means of petrographic observation,semi-quantitative analysis of chemical composition,fabric identification of minerals and integrated mineral phase analysis,while studying the mineralogy of SG 013,and the fabric characteristics of SG 013 are studied in detail.Different from previous studies,here we find that Lithology 1 of SG 013 contains non-porphyritic chondrules and metallic silicate globules,while Lithology 2 not only contains nonporphyritic chondrules and metallic-silicate globules,but also porphyritic chondrules.In this thesis,Electron backscatter diffraction(EBSD)analysis of magnesium olivine in metal-silicate globules and porphyritic chondrules in L2 of SG 013 shows that some magnesium olivine form under conditions of lower temperature and faster strain rate during uniaxial compression,where deformation of the olivine is dominated by dislocation glide.However,at higher temperatures and slower strain rates,the fabric of B-axis([100])is concentrated,indicating that the porphyritic chondrules may be dominated by the compaction of olivine particles,leading to dynamic recrystallization in the peripheral region or outer layer of the magnesium olivine crystal.New grains formed by dynamic recrystallization occur at the edges of residual grains and,their orientation is controlled by stress.It is found that the formation position of magnesium olivine in different chondrules of SG 013 from the inside out,with the gradual reduction of stress and the gradual increase of temperature,these local physicochemical changes reveal the complex thermal history and dynamic processes that chondrules undergo during their formation and evolution.展开更多
Recovered samples of Jilin H5 chondrite experimentally shocked to 12-133 GPa were studied to explore the behavior of opaque minerals under shock loading using SEM-EDS,Raman spectroscopy,and TIMA.The following results ...Recovered samples of Jilin H5 chondrite experimentally shocked to 12-133 GPa were studied to explore the behavior of opaque minerals under shock loading using SEM-EDS,Raman spectroscopy,and TIMA.The following results were obtained.Firstly,at pressures lower than 53GPa,the opaque minerals still keep the unmelted state,while at 78 GPa and higher,FeNi metal and troilite form eutectic intergrowths occurring as disorderly fine veinlets filling the shock-induced fractures in silicate minerals.Secondly,single kamacite grains still maintain their contour at 12 GPa,but a part of brittle troilite grains was fragmented and squeezed into the shock-induced fractures within kamacite grains.At53 and 133 GPa,many more troilite fragments are poured in the kamacite interior to form disordered hybrid aggregates or to form squiggly strips,respectively.Similar phenomena are observed within single troilite grains,but the mineral squeezed into troilite grains is kamacite.Thirdly,chromite is a hard and refractory oxide mineral.When the shock pressure rises step by step from 12 to 133 GPa,the shock effect of chromite is only fragmentation.Its grain size decreases from tens of um at 53 GPa to a few um at 133 GPa.And,fourthly,native copper exhibits distinct redistribution behavior at high temperature.In Jilin samples shock-loaded to 12 GPa,copper initially located at troilite-kamacite interfaces partially transferred into small troilite grains containing fine FeNi particles.At 53 and 133 GPa,native copper preferentially transferred into larger troilite grains containing more particles of eutectic FeNi metal.展开更多
CM chondrites contain valuable insights into the formation and evolution of the solar nebula,as well as the secondary aqueous alteration processes that affected their parent bodies.Our study focuses on primary and sec...CM chondrites contain valuable insights into the formation and evolution of the solar nebula,as well as the secondary aqueous alteration processes that affected their parent bodies.Our study focuses on primary and secondary sulfides within the Aguas Zarcas(CM2)chondrite,investigating their formation mechanisms based on their morphology,textures,and compositions.Moreover,we infer the formation temperatures of the sulfides from 230 to 500℃ for primary and from 100 to 135℃ for secondary.We select representative grains and conduct Fe isotope measurements on them.The primary sulfides with δ^(56/54)Fe ranging from -2.44‰ to +0.69‰are associated with sulfidesilicate melt segregation,while secondary sulfides with δ^(56/54)Fe values between -1.83‰ and -0.14‰ are linked to aqueous alteration.Overall,the Ni content of the grains is positively correlated with δ^(56/54)Fe.It might be related to the changes in crystal structure and chemical bond lengths due to the increase in nickel content.Fe isotopes provide a new perspective on sulfide formation and the evolution of a carbonaceous chondrite parent body.展开更多
Kinetic impact is the most practical planetary-defense technique,with momentum-transfer efficiency central to deflection design.We present a Monte Carlo photometric framework that couples ejecta sampling,dynamical evo...Kinetic impact is the most practical planetary-defense technique,with momentum-transfer efficiency central to deflection design.We present a Monte Carlo photometric framework that couples ejecta sampling,dynamical evolution,and image synthesis to compare directly with HST,LICIACube,ground-based and Lucy observations of the DART impact.Decomposing ejecta into(1)a highvelocity(~1600 m/s)plume exhibiting Na/K resonance,(2)a low-velocity(~1 m/s)conical component shaped by binary gravity and solar radiation pressure,and(3)meter-scale boulders,we quantify each component’s mass and momentum.Fitting photometric decay curves and morphological evolution yields size-velocity distributions and,via scaling laws,estimates of Dimorphos’bulk density,cratering parameters,and cohesive strength that agree with dynamical constraints.Photometric ejecta modeling therefore provides a robust route to constrain momentum enhancement and target properties,improving predictive capability for kinetic-deflection missions.展开更多
The Martian core mainly contains iron,nickel and some light elements.However,controversies remain about the structure and chemical composition of the Martian core due to a lack of samples and marsquake data.Recently,t...The Martian core mainly contains iron,nickel and some light elements.However,controversies remain about the structure and chemical composition of the Martian core due to a lack of samples and marsquake data.Recently,the InSight lander collected long-term marsquake data,which improved the Martian interior structure model.B ased on the preliminary analysis of marsquake data,Mars has a molten liquid core with a radius of around 1700 km.As the Martian core has a smaller density and lower temperature than pure iron at corresponding pressure and temperature conditions,some light elements are introduced to reduce the density and liquidus temperature.With various methods for seismic analysis,in-situ high-pressure and high-temperature experiments,and first-principal calculations,the Martian core composition and evolution models have been updated in the past few years.Here,we review those studies on the light elements in the Martian core from four aspects including(1)high-temperature and high-pressure experiments,(2)marsquake data,(3)mineral physics model with molecular dynamics simulations and(4)cosmochemistry investigation.We discussed the effect of different light elements on the Martian core s density,sound velocity and liquidus temperature.Moreover,the review examines the varieties,abundances and forms of light elements in the Martian core.展开更多
Brachinite is a group of primitive achondrites that enables investigating the evolution of asteroids not fully diff erentiated in the early stage of the solar system.Kumtag 061 is a new meteorite sample collected on O...Brachinite is a group of primitive achondrites that enables investigating the evolution of asteroids not fully diff erentiated in the early stage of the solar system.Kumtag 061 is a new meteorite sample collected on October 27,2019,in Kumtag Desert,Xinjiang Province,China.The oxygen isotope composition(δ^(18)O=5.086‰,δ^(17)O=2.396‰,Δ’^(17)O=-0.298‰)and petrologic and mineralogic analysis suggest Kumtag 061 is a heavy-impacted brachinite(S4-S5).The geochemical composition suggests Kumtag 061 represents a partial melting residue of the brachinite parent body.Based on the noble gas composition,the cosmic ray exposure age of Kumtag 061 is 60.9±9.0 Ma.Combined with the gas retention ages,they indicate a(series of)thermal events on the parent body of brachinites before Kumtag 061 was ejected into space.展开更多
Near-Earth objects are important not only in studying the early formation of the Solar System,but also because they pose a serious hazard to humanity when they make close approaches to the Earth.Study of their physica...Near-Earth objects are important not only in studying the early formation of the Solar System,but also because they pose a serious hazard to humanity when they make close approaches to the Earth.Study of their physical properties can provide useful information on their origin,evolution,and hazard to human beings.However,it remains challenging to investigate small,newly discovered,near-Earth objects because of our limited observational window.This investigation seeks to determine the visible colors of near-Earth asteroids(NEAs),perform an initial taxonomic classification based on visible colors and analyze possible correlations between the distribution of taxonomic classification and asteroid size or orbital parameters.Observations were performed in the broadband BVRI Johnson−Cousins photometric system,applied to images from the Yaoan High Precision Telescope and the 1.88 m telescope at the Kottamia Astronomical Observatory.We present new photometric observations of 84 near-Earth asteroids,and classify 80 of them taxonomically,based on their photometric colors.We find that nearly half(46.3%)of the objects in our sample can be classified as S-complex,26.3%as C-complex,6%as D-complex,and 15.0%as X-complex;the remaining belong to the A-or V-types.Additionally,we identify three P-type NEAs in our sample,according to the Tholen scheme.The fractional abundances of the C/X-complex members with absolute magnitude H≥17.0 were more than twice as large as those with H<17.0.However,the fractions of C-and S-complex members with diameters≤1 km and>1 km are nearly equal,while X-complex members tend to have sub-kilometer diameters.In our sample,the C/D-complex objects are predominant among those with a Jovian Tisserand parameter of T_(J)<3.1.These bodies could have a cometary origin.C-and S-complex members account for a considerable proportion of the asteroids that are potentially hazardous.展开更多
Understanding the interaction of Martian rocks and the environment is conducive to Mars in situ resource utilization(ISRU) and the search for natural H_(2) reservoirs. Here, we report an interesting finding: using a r...Understanding the interaction of Martian rocks and the environment is conducive to Mars in situ resource utilization(ISRU) and the search for natural H_(2) reservoirs. Here, we report an interesting finding: using a real Martian meteorite(NWA13190) and within Mars' temperature range(25℃), we confirmed spontaneous hydrogen generation from the reaction of water, CO_(2), and Martian rock—no external energy or catalysts required. The reaction produced hydrogen at ~4 ppm/day, stabilizing after 9 days, alongside newly formed carbonate and sulfate minerals absent in the original meteorite. Mechanistic analyses using XPS(X-ray photoelectron spectroscopy), M??ssbauer spectroscopy, and FTIR(Fourier transform infrared spectroscopy) revealed that Fe^(2+) in Fe TiO_(3) and FeS_(2)(not pyroxene) oxidized to Fe^(3+), driving water reduction to hydrogen. The buffer effect of CO_(2) sustained acidic conditions, enhancing Fe^(2+) release and H_(2) production. These results align with in situ Mars detections(e.g., Ca-sulfate veins by Curiosity). Compared with energy-intensive electrolysis-based ISRU, this geological process offers a more efficient H_(2) production pathway. It also provides theoretical support for natural hydrogen reservoirs on Mars and simultaneously advances understanding of Mars' early atmospheric evolution and potential life-supporting environments.展开更多
基金financial support from Shanghai Key Laboratory Novel Extreme Condition Materials,China(Grant No.22dz2260800)the Shanghai Science and Technology Committee,China(Grant No.22JC1410300).
文摘The newly identified Jinlin crater in southern China lies on a hillside covered by a thick granite weathering crust.It appears as a slightly elliptical bowl-shaped depression with a diameter of 820-900 m.The structure is a tilted impact crater,showing a maximum rim height difference of about 200 m and an apparent depth of 90 m.The crater rim is composed mainly of granite weathered soil and a small amount of granite fragments,while the bottom of the crater is filled with the same mixture of granite weathered soil and granite fragments.Planar deformation features in quartz grains from the rock fragments of the crater provide decisive evidence for its impact origin.The impact event is inferred to have taken place during the Holocene.
基金Chinese Academy of Science,XDB 41000000,Chunhui Li。
文摘CB chondrite is a class of meteorite rich in metal composition,and its characteristics are obviously different from other chondrite groups.These meteorites are distinguished by their content of up to 60% to 70%FeNi metals and sulfides,in addition to their extreme lack of volatile and moderately volatile elements,less refractory inclusions,and almost no fine-grained matrix.Sierra Gorda 013(SG013)is a metal-rich chondritic meteorite of the CBa type.It has two different lithologies within SG 013:Lithology 1and Lithology 2.Lithology 1 is an anomalous CBa chondrite containing chromite-pyroxene complex assemblage,whereas Lithology 2 is featured by recrystallization with small chondrules and contains much less iron nickel metal than Lithology 1.Although the two lithologies have essentially the same oxygen isotope composition,their structures are different from each other,suggesting that they probably underwent distinct formation and evolution processes from common precursors.In this study,the mineralogy of SG013 chondrites is studied by means of petrographic observation,semi-quantitative analysis of chemical composition,fabric identification of minerals and integrated mineral phase analysis,while studying the mineralogy of SG 013,and the fabric characteristics of SG 013 are studied in detail.Different from previous studies,here we find that Lithology 1 of SG 013 contains non-porphyritic chondrules and metallic silicate globules,while Lithology 2 not only contains nonporphyritic chondrules and metallic-silicate globules,but also porphyritic chondrules.In this thesis,Electron backscatter diffraction(EBSD)analysis of magnesium olivine in metal-silicate globules and porphyritic chondrules in L2 of SG 013 shows that some magnesium olivine form under conditions of lower temperature and faster strain rate during uniaxial compression,where deformation of the olivine is dominated by dislocation glide.However,at higher temperatures and slower strain rates,the fabric of B-axis([100])is concentrated,indicating that the porphyritic chondrules may be dominated by the compaction of olivine particles,leading to dynamic recrystallization in the peripheral region or outer layer of the magnesium olivine crystal.New grains formed by dynamic recrystallization occur at the edges of residual grains and,their orientation is controlled by stress.It is found that the formation position of magnesium olivine in different chondrules of SG 013 from the inside out,with the gradual reduction of stress and the gradual increase of temperature,these local physicochemical changes reveal the complex thermal history and dynamic processes that chondrules undergo during their formation and evolution.
基金Science and Technology Planning Project of Guangdong Province,2023B1212060048,Xiande Xie。
文摘Recovered samples of Jilin H5 chondrite experimentally shocked to 12-133 GPa were studied to explore the behavior of opaque minerals under shock loading using SEM-EDS,Raman spectroscopy,and TIMA.The following results were obtained.Firstly,at pressures lower than 53GPa,the opaque minerals still keep the unmelted state,while at 78 GPa and higher,FeNi metal and troilite form eutectic intergrowths occurring as disorderly fine veinlets filling the shock-induced fractures in silicate minerals.Secondly,single kamacite grains still maintain their contour at 12 GPa,but a part of brittle troilite grains was fragmented and squeezed into the shock-induced fractures within kamacite grains.At53 and 133 GPa,many more troilite fragments are poured in the kamacite interior to form disordered hybrid aggregates or to form squiggly strips,respectively.Similar phenomena are observed within single troilite grains,but the mineral squeezed into troilite grains is kamacite.Thirdly,chromite is a hard and refractory oxide mineral.When the shock pressure rises step by step from 12 to 133 GPa,the shock effect of chromite is only fragmentation.Its grain size decreases from tens of um at 53 GPa to a few um at 133 GPa.And,fourthly,native copper exhibits distinct redistribution behavior at high temperature.In Jilin samples shock-loaded to 12 GPa,copper initially located at troilite-kamacite interfaces partially transferred into small troilite grains containing fine FeNi particles.At 53 and 133 GPa,native copper preferentially transferred into larger troilite grains containing more particles of eutectic FeNi metal.
基金supported by the National Science Foundation of China(Nos.42225202 and 41827802)。
文摘CM chondrites contain valuable insights into the formation and evolution of the solar nebula,as well as the secondary aqueous alteration processes that affected their parent bodies.Our study focuses on primary and secondary sulfides within the Aguas Zarcas(CM2)chondrite,investigating their formation mechanisms based on their morphology,textures,and compositions.Moreover,we infer the formation temperatures of the sulfides from 230 to 500℃ for primary and from 100 to 135℃ for secondary.We select representative grains and conduct Fe isotope measurements on them.The primary sulfides with δ^(56/54)Fe ranging from -2.44‰ to +0.69‰are associated with sulfidesilicate melt segregation,while secondary sulfides with δ^(56/54)Fe values between -1.83‰ and -0.14‰ are linked to aqueous alteration.Overall,the Ni content of the grains is positively correlated with δ^(56/54)Fe.It might be related to the changes in crystal structure and chemical bond lengths due to the increase in nickel content.Fe isotopes provide a new perspective on sulfide formation and the evolution of a carbonaceous chondrite parent body.
基金supported by the National Natural Science Foundation of China(Grant No.12272018)the National Key Basic Research Project(2022JCJQZD20600).
文摘Kinetic impact is the most practical planetary-defense technique,with momentum-transfer efficiency central to deflection design.We present a Monte Carlo photometric framework that couples ejecta sampling,dynamical evolution,and image synthesis to compare directly with HST,LICIACube,ground-based and Lucy observations of the DART impact.Decomposing ejecta into(1)a highvelocity(~1600 m/s)plume exhibiting Na/K resonance,(2)a low-velocity(~1 m/s)conical component shaped by binary gravity and solar radiation pressure,and(3)meter-scale boulders,we quantify each component’s mass and momentum.Fitting photometric decay curves and morphological evolution yields size-velocity distributions and,via scaling laws,estimates of Dimorphos’bulk density,cratering parameters,and cohesive strength that agree with dynamical constraints.Photometric ejecta modeling therefore provides a robust route to constrain momentum enhancement and target properties,improving predictive capability for kinetic-deflection missions.
基金financially supported by the National Natural Science Foundation of China(grant no.42120104005)Guizhou Provincial 2021 Science and Technology Subsidies(grant no.GZ2021SIG)+1 种基金Guizhou Provincial Science and Technology Projects(grant nos.ZK[2024]087GCC[2023]060)。
文摘The Martian core mainly contains iron,nickel and some light elements.However,controversies remain about the structure and chemical composition of the Martian core due to a lack of samples and marsquake data.Recently,the InSight lander collected long-term marsquake data,which improved the Martian interior structure model.B ased on the preliminary analysis of marsquake data,Mars has a molten liquid core with a radius of around 1700 km.As the Martian core has a smaller density and lower temperature than pure iron at corresponding pressure and temperature conditions,some light elements are introduced to reduce the density and liquidus temperature.With various methods for seismic analysis,in-situ high-pressure and high-temperature experiments,and first-principal calculations,the Martian core composition and evolution models have been updated in the past few years.Here,we review those studies on the light elements in the Martian core from four aspects including(1)high-temperature and high-pressure experiments,(2)marsquake data,(3)mineral physics model with molecular dynamics simulations and(4)cosmochemistry investigation.We discussed the effect of different light elements on the Martian core s density,sound velocity and liquidus temperature.Moreover,the review examines the varieties,abundances and forms of light elements in the Martian core.
基金supported by the Project of Highlevel Innovative Talents of Guizhou Province(GCC[2022]017-1)the National Natural Science Foundation of China(grant no.42173046)。
文摘Brachinite is a group of primitive achondrites that enables investigating the evolution of asteroids not fully diff erentiated in the early stage of the solar system.Kumtag 061 is a new meteorite sample collected on October 27,2019,in Kumtag Desert,Xinjiang Province,China.The oxygen isotope composition(δ^(18)O=5.086‰,δ^(17)O=2.396‰,Δ’^(17)O=-0.298‰)and petrologic and mineralogic analysis suggest Kumtag 061 is a heavy-impacted brachinite(S4-S5).The geochemical composition suggests Kumtag 061 represents a partial melting residue of the brachinite parent body.Based on the noble gas composition,the cosmic ray exposure age of Kumtag 061 is 60.9±9.0 Ma.Combined with the gas retention ages,they indicate a(series of)thermal events on the parent body of brachinites before Kumtag 061 was ejected into space.
基金funded by the China National Space Administration(KJSP2023020105)supported by the National Key R&D Program of China(Grant No.2023YFA1608100)+2 种基金the NSFC(Grant No.62227901)the Minor Planet Foundationsupported by the Egyptian Science,Technology&Innovation Funding Authority(STDF)under Grant No.48102.
文摘Near-Earth objects are important not only in studying the early formation of the Solar System,but also because they pose a serious hazard to humanity when they make close approaches to the Earth.Study of their physical properties can provide useful information on their origin,evolution,and hazard to human beings.However,it remains challenging to investigate small,newly discovered,near-Earth objects because of our limited observational window.This investigation seeks to determine the visible colors of near-Earth asteroids(NEAs),perform an initial taxonomic classification based on visible colors and analyze possible correlations between the distribution of taxonomic classification and asteroid size or orbital parameters.Observations were performed in the broadband BVRI Johnson−Cousins photometric system,applied to images from the Yaoan High Precision Telescope and the 1.88 m telescope at the Kottamia Astronomical Observatory.We present new photometric observations of 84 near-Earth asteroids,and classify 80 of them taxonomically,based on their photometric colors.We find that nearly half(46.3%)of the objects in our sample can be classified as S-complex,26.3%as C-complex,6%as D-complex,and 15.0%as X-complex;the remaining belong to the A-or V-types.Additionally,we identify three P-type NEAs in our sample,according to the Tholen scheme.The fractional abundances of the C/X-complex members with absolute magnitude H≥17.0 were more than twice as large as those with H<17.0.However,the fractions of C-and S-complex members with diameters≤1 km and>1 km are nearly equal,while X-complex members tend to have sub-kilometer diameters.In our sample,the C/D-complex objects are predominant among those with a Jovian Tisserand parameter of T_(J)<3.1.These bodies could have a cometary origin.C-and S-complex members account for a considerable proportion of the asteroids that are potentially hazardous.
基金supported by the National Natural Science Foundation of China (Grant Nos.41807188,42402285,51978537,52270165)the Fundamental Research Funds for the Central Universities (Grant No.2042021kf0201)Start-up Fund for Distinguished Scholars,Wuhan University (Grant Nos.1403-413100041,1403-600460022)。
文摘Understanding the interaction of Martian rocks and the environment is conducive to Mars in situ resource utilization(ISRU) and the search for natural H_(2) reservoirs. Here, we report an interesting finding: using a real Martian meteorite(NWA13190) and within Mars' temperature range(25℃), we confirmed spontaneous hydrogen generation from the reaction of water, CO_(2), and Martian rock—no external energy or catalysts required. The reaction produced hydrogen at ~4 ppm/day, stabilizing after 9 days, alongside newly formed carbonate and sulfate minerals absent in the original meteorite. Mechanistic analyses using XPS(X-ray photoelectron spectroscopy), M??ssbauer spectroscopy, and FTIR(Fourier transform infrared spectroscopy) revealed that Fe^(2+) in Fe TiO_(3) and FeS_(2)(not pyroxene) oxidized to Fe^(3+), driving water reduction to hydrogen. The buffer effect of CO_(2) sustained acidic conditions, enhancing Fe^(2+) release and H_(2) production. These results align with in situ Mars detections(e.g., Ca-sulfate veins by Curiosity). Compared with energy-intensive electrolysis-based ISRU, this geological process offers a more efficient H_(2) production pathway. It also provides theoretical support for natural hydrogen reservoirs on Mars and simultaneously advances understanding of Mars' early atmospheric evolution and potential life-supporting environments.
