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
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
The SiTian project,with its vast field of view,will become an ideal platform for scientific research on asteroids.In this study,we develop a pipeline to analyze the photometry of asteroids and derive their periods fro...The SiTian project,with its vast field of view,will become an ideal platform for scientific research on asteroids.In this study,we develop a pipeline to analyze the photometry of asteroids and derive their periods from the data collected by the SiTian pathfinder project Mini-SiTian(MST).The pipeline is applied to the MST f02 region,an MST test region with a sky area of 2°.29×1°.53.Rotation periods of 22 asteroids are derived by the obtained light curve analysis.Among them,there are eight asteroids available in the Asteroid Lightcurve Photometry Database(ALCDEF),and six of them with more photometric points(>200)that have similar period parameters as the ones in ALCDEF.Additionally,the periods for 14 of these asteroids are newly obtained and are not listed in ALCDEF.This study demonstrates the feasibility of asteroid photometric research by the SiTian project.It shows that future observations from the SiTian project will provide even more photometry of asteroids,significantly increasing the number of available light curves.The potential vast photometric data on asteroids will help us to further understand the physics of asteroids,their material composition,and the formation and evolution of the solar system.展开更多
The perihelion of long-period comets places them near the Sun so they may exhibit activity.Before 2013 LU28 reached its perihelion,we performed a continuous observation to detect possible activity.Using the Lijiang 2....The perihelion of long-period comets places them near the Sun so they may exhibit activity.Before 2013 LU28 reached its perihelion,we performed a continuous observation to detect possible activity.Using the Lijiang 2.4 m telescope with a Johnson R filter,we measured the brightness of 2013 LU28 from 2024 January 3 to April 13.The instrumental magnitudes were subsequently transformed into the Pan-STARRS r system.Due to the noticeable descending trend in the absolute magnitude,we verified the cometary activity and constrained some photometric properties of 2013 LU28.Consequently,the increased cross-sectional area had a rate of 42.8 km^(2)day^(−1),and the corresponding mass-loss rate was 2.64 kg s^(−1)with the assumption of a dust-particle size a=10 mm and the densityρ=400 kg m^(−3).We estimated the nucleus radius as 0.11■r_(n)■0.21 km for CO sublimation and 0.20■r_(n)■0.71 km for CO_(2)sublimation and the grain size of 2013 LU28 was ac;117.95μm for CO and ac■7.57μm for CO_(2).The long-term observations provided in this paper will offer significant value for investigating the mechanisms driving the activity of 2013 LU28.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 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supports from the National Natural Science Foundation of China(NSFC,grant Nos.12203002 and 11973015)supports from the National Key Basic R&D Program of China via 2023YFA1608303 and the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB0550103)+6 种基金supports from the National Natural Science Foundation of China(NSFCgrant No.12373015)supports from the National Natural Science Foundation of China(NSFCgrant Nos.12120101003 and 12373010)National Key R&D Program of China(grant Nos.2023YFA1607800,2023YFA1607804,2022YFA1602902)Beijing Municipal Natural Science Foundation(grant No.1222028)Strategic Priority Research Program of the Chinese Academy of Science(grant Nos.XDB0550100 and XDB0550000).
文摘The SiTian project,with its vast field of view,will become an ideal platform for scientific research on asteroids.In this study,we develop a pipeline to analyze the photometry of asteroids and derive their periods from the data collected by the SiTian pathfinder project Mini-SiTian(MST).The pipeline is applied to the MST f02 region,an MST test region with a sky area of 2°.29×1°.53.Rotation periods of 22 asteroids are derived by the obtained light curve analysis.Among them,there are eight asteroids available in the Asteroid Lightcurve Photometry Database(ALCDEF),and six of them with more photometric points(>200)that have similar period parameters as the ones in ALCDEF.Additionally,the periods for 14 of these asteroids are newly obtained and are not listed in ALCDEF.This study demonstrates the feasibility of asteroid photometric research by the SiTian project.It shows that future observations from the SiTian project will provide even more photometry of asteroids,significantly increasing the number of available light curves.The potential vast photometric data on asteroids will help us to further understand the physics of asteroids,their material composition,and the formation and evolution of the solar system.
基金Funding for the telescope has been provided by CAS and the People’s Government of Yunnan Provincefunded by the Civil Aerospace pre-research project D020302+2 种基金National Natural Science Foundation of China (U12150009,12150009)the CAS Light of West China Programthe science research grants from the China Manned Space Project with NO.CMS-CSST-2021-B10
文摘The perihelion of long-period comets places them near the Sun so they may exhibit activity.Before 2013 LU28 reached its perihelion,we performed a continuous observation to detect possible activity.Using the Lijiang 2.4 m telescope with a Johnson R filter,we measured the brightness of 2013 LU28 from 2024 January 3 to April 13.The instrumental magnitudes were subsequently transformed into the Pan-STARRS r system.Due to the noticeable descending trend in the absolute magnitude,we verified the cometary activity and constrained some photometric properties of 2013 LU28.Consequently,the increased cross-sectional area had a rate of 42.8 km^(2)day^(−1),and the corresponding mass-loss rate was 2.64 kg s^(−1)with the assumption of a dust-particle size a=10 mm and the densityρ=400 kg m^(−3).We estimated the nucleus radius as 0.11■r_(n)■0.21 km for CO sublimation and 0.20■r_(n)■0.71 km for CO_(2)sublimation and the grain size of 2013 LU28 was ac;117.95μm for CO and ac■7.57μm for CO_(2).The long-term observations provided in this paper will offer significant value for investigating the mechanisms driving the activity of 2013 LU28.
