Observation and Research on Strong Meteor Showers and Their Catastrophic Space Weather Events     

Yue-hua Ma  You-wen He  Pin-xin Xu  Hai-bin Zhao 《Chinese Astronomy and Astrophysics》2008,32(2):186-196

During the first international joint observation of the Leo strong meteor shower, multidisciplinary and multi-media synthetic observation of Leo and Draco strong meteor showers and their catastrophic space weather events were carried out. The comprehensive analysis of the observed and related data of the Leo, Perseus and Draco strong meteor showers obtained for near half a century (from 1957 to 2003) fully verifies that the non-sporadic periodic strong meteor shower may lead to catastrophic space weather events. Preliminary identification is made of the following: the mechanism of formation of strong meteor showers, the law of occurrence of the f_bE_s abnormal peak and serious safety hazards for astronavigation. Also discussed in this paper are the evolutionary process of cometary dust, the law of occurrence and loss of cosmic dust storm and the mechanism of maintaining cosmic dust in the mid-latitude E_s layer.  相似文献   

Bulk compositions of metallic Fe-Ni of chondrites： Constraints on fractionation of siderophile and chalcophile elements     

XU Lin    LIN Yangting  WANG Shijie    OUYANG Ziyuan Key Laboratory of the Study of Earth’s Deep Interior  Institute of Geology  Geophysics  Chinese Academy of Sciences  Beijing  China National Astronomical Observatories  Beijing  China Institute of Geochemistry  Guiyang  China 《中国地球化学学报》2009,28(3):271-278

Bulk compositions of metallic Fe-Ni from two equilibrated ordinary chondrites, Jilin (H5) and Anlong (H5), and two unequilibrated ones, GRV 9919 (L3) and GRV 021603 (H3), were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). The CI-, Co-normalized abundances of siderophile and chalcophile elements of metallic Fe-Ni from the unequilibrated ordinary chondrites correlate with 50% condensation temperatures (i.e., volatility) of the elements. The refractory siderophile elements (i.e., platinum group elements, Re), Au, Ni and Co show a flat pattern (1.01×CI Co-normalized), while moderate elements (As, Cu, Ag, Ga, Ge, Zn) decrease with volatility from 0.63×CI (Co-normalized, As) to 0.05×CI (Co-normalized, Zn). Cr and Mn show deficit relative to the trend, probably due to their main partition in silicates and sulfides (nonmagnetic). Metallic Fe-Ni from the equilibrated ordinary chondrites shows similar patterns, except for strong deficit of Cr, Mn, Ag and Zn. It is indicated that these elements were almost all partitioned into silicates and/or sulfides during thermal metamorphism. The similar deficit of Cr, Mn, Ag and Zn was also found in iron meteorites. Our analyses demonstrate similar behaviors of W and Mo as refractory siderophile elements during condensation of the solar nebula, except for slight depletion of Mo in the L3 and H5 chondrites. The Mo-depletion of metallic Fe-Ni from GRV 9919 (L3) relative to GRV 021603 (H3) could be due to a more oxidizing condition of the former than the latter in the solar nebula. In contrast, the Mo-depletion of the metallic Fe-Ni from the H5 chondrites may reflect partition of Mo from metal to silicates and/or sulfides during thermal metamorphism in the asteroidal body.  相似文献   

Roaldite in the iron-meteorite São Julião de Moreira     

《Chemie der Erde / Geochemistry》2019,79(4):125538

Roaldite – Fe₄N – has been identified in the São Julião de Moreira iron meteorite using electron backscatter diffraction (EBSD) and simultaneously acquired energy-dispersive x-ray spectroscopy (EDS). Mean-periodic-number images derived from raw EBSD patterns confirm this phase by an even higher spatial resolution compared to EDS.Roaldite appears in the form of systematically and repetitively aligned plates. Despite the locally heavy plastic deformation, it is shown that the origin of the oriented precipitation of roaldite is linked to the orientation of the kamacite matrix. Roaldite can be considered to be precipitated from kamacite using an inverse Kurdjumov-Sachs (K-S) or Nishiyama-Wassermann (N-W) orientation relationship. A more accurate discrimination is impossible due to the accumulated shock deformation, which blurs the local reference orientation of kamacite. The habit plane of roaldite is found to be {112}_R, which is most likely parallel to {120}_K of kamacite. Some of the roaldite plates contain two orientation variants which repeatedly alternate. Their misorientation angle is about 12°.  相似文献   

SIMS Pb/Pb dating of Zr-rich minerals in lunar meteorites Miller Range 05035 and LaPaz Icefield 02224:Implications for the petrogenesis of mare basalt   总被引：1，自引：0，他引：1  

HSU WeiBiao 《中国科学:地球科学(英文版)》2010,(3)

Miller Range (MIL) 05035 and LaPaz Icefield (LAP) 02224 are unbrecciated lunar basalt meteorites. In this report, we studied their petrography and mineralogy and made in situ uranogenic Pb/Pb dating of Zr-rich minerals. Petrography and mineralogy of these two lunar meteorites are consistent with previous investigations. The zirconolite Pb/Pb age of MIL 05035 is 3851±8 Ma (2σ), in excellent agreement with previous reports. This age suggests that MIL 05035 could be paired with Asuka 881757, a low-Ti mare basalt meteorite. The magmatic event related to MIL 05035 was probably due to the late heavy impact bom- bardment on the moon around 3.9 Ga. One baddeleyite grain in LAP 02224 shows a large variation of Pb/Pb age, from 3109±29 to 3547±21 Ma (2σ), much older than the whole-rock age of the same meteorite (~3.02±0.03 Ga). The other baddeleyite grain in LAP 02224 has an age of 3005±17 Ma (2σ). The result indicates that the minimum crystallization age of LAP 02224 is ~3.55 Ga and the younger ages could reflect late thermal disturbance on U-Pb system.  相似文献   

Bulk Chemical Composition of the Ningqiang Carbonaceous Chondrite： An Issue of Classification   总被引：1，自引：0，他引：1  

WANG Guiqin LIN Yangting 《《地质学报》英文版》2007,81(1):141-147

The Ningqiang meteorite is a fall carbonaceous chondrite, containing various Ca-, Al-rich inclusions that usually escaped from secondary events such as high-temperature heating and low- temperature alteration. However, it has not yet been classified into any known chemical group. In order to address this issue, 41 elements of the bulk Ningqiang meteorite were analyzed using inductively coupled plasma mass spectrometry （ICP-MS） and inductively coupled plasma atom emission spectrometry （ICP-AES） in this study. The Allende （CV3） carbonaceous chondrite and the Jilin （H5） ordinary chondrite were also measured as references, and our analyses are consistent with the previous results. Rare earth and other refractory lithophile elements are depleted in Ningqiang relative to both Allende and mean CK chondrites. In addition, the REE pattern of Ningqiang is nearly flat, while that of Allende shows slight enrichment of LREE relative to HREE. Siderophile elements of Ningqiang are close to those of mean CK chondrites, but lower than those of Allende. Our new analyses indicate that Ningqiang cannot be classified into any known group of carbonaceous chondrites, consistent with previous reports.  相似文献   

陨石中宇宙成因核素~(10)Be和~(26)Al的化学分离纯化     

《地球化学》2008,(2)

陨石离开其小行星母体直至降到地球表面期间,受到宇宙射线的照射,产生一系列包括10Be和26Al等的放射性核素。10Be和26Al的含量及其比值记录了宇宙射线辐照历史,而陨石降落到地球表面后,它们的衰变又提供了测定其降落时间,即居地年龄的方法。10Be和26Al由加速器质谱测定,样品需分离纯化。为此,开展了陨石样品Be和Al的分离纯化实验。通过模拟样品的条件实验,建立了Be和Al分离纯化的化学流程,其回收率分别达到89%和70%。在此基础上,分离并测定了一个降落型普通球粒陨石(吉林陨石)非磁性部分的10Be和26Al的含量。结果显示,吉林陨石26Al/10Be的比值为5.005,远大于两者的饱和比值(2.72),说明吉林陨石经历了短期的暴露辐射,这一结果与吉林陨石第二阶段的暴露年龄0.4Ma一致。整个化学流程的10Be/9Be和26Al/27Al空白分别为(4.33±0.46)×10-14和(6.59±4.66)×10-15,其中前者接近于该仪器的空白测量值,而后者则接近于仪器的检测限2.3×10-15。  相似文献   

极地微陨石的收集、研究与设想          下载免费PDF全文

夏志鹏  缪秉魁  张川统  黄丽霖 《极地研究》2018,30(3):314-328

微陨石对于人类研究地外环境和太阳系的演化而言,具有极其重要的意义。20世纪40年代开始,微陨石的收集便成了国际上的热点。尤其是80年代后,通过在南北两极开展微陨石收集,产出了大量的科学成果。我国的微陨石研究主要集中在20世纪80—90年代,而后便处于停滞的状态。本文简要介绍了各国在极地微陨石方面取得的成果,基于我国陨石和微陨石的研究现状,对我国开展极地微陨石研究提出了几点设想和规划。  相似文献   

Geology of five small Australian impact craters     

E. M. Shoemaker  F. A. Macdonald  C. S. Shoemaker 《Australian Journal of Earth Sciences》2013,60(4-5):529-544

Here we present detailed geological maps and cross-sections of Liverpool, Wolfe Creek, Boxhole, Veevers and Dalgaranga craters. Liverpool crater and Wolfe Creek Meteorite Crater are classic bowl-shaped, Barringer-type craters. Liverpool was likely formed during the Neoproterozoic and was filled and covered with sediments soon thereafter. In the Cenozoic, this cover was exhumed exposing the crater's brecciated wall rocks. Wolfe Creek Meteorite Crater displays many striking features, including well-bedded ejecta units, crater-floor faults and sinkholes, a ringed aeromagnetic anomaly, rim-skirting dunes, and numerous iron-rich shale balls. Boxhole Meteorite Crater, Veevers Meteorite Crater and Dalgaranga crater are smaller, Odessa-type craters without fully developed, steep, overturned rims. Boxhole and Dalgaranga craters are developed in highly foliated Precambrian basement rocks with a veneer of Holocene colluvium. The pre-existing structure at these two sites complicates structural analyses of the craters, and may have influenced target deformation during impact. Veevers Meteorite Crater is formed in Cenozoic laterites, and is one of the best-preserved impact craters on Earth. The craters discussed herein were formed in different target materials, ranging from crystalline rocks to loosely consolidated sediments, containing evidence that the impactors struck at an array of angles and velocities. This facilitates a comparative study of the influence of these factors on the structural and topographic form of small impact craters.  相似文献   

Space weathering simulation and spectrum decoding     

Sen Hu  Yangting Lin 《中国地球化学学报》2012,31(2):128-135

Visible and near-infrared spectra are routinely used to achieve mineral abundances and mineral chemistry of the global surfaces of the Moon and asteroids.However,these spectra can be significantly modified by space weathering,including micrometeorite impacting,solar wind implanting and cosmic ray irradiation.In this paper we report results of laser-bombarding experiments on the Jilin ordinary chondrite,simulating micrometeorite impacting on the surface of asteroids.After laser bombardment,the spectra became significantly redder and moderately darker. With the Modified Gaussian Model(MGM)method,the absorption band positions of olivine can be decoded from the modified spectra,which are correlated with their fayalite contents.In addition,a continuum of the modified spectra can be decoded,and its slope may be used to depict the degree of space weathering.However,relative strengths of the absorption sub-bands of olivine and pyroxenes show significant variant after the bombardment, hence they cannot be used to estimate the relative abundances of high-Ca to low-Ca pyroxenes of the lunar surface and other matured surfaces of asteroids.  相似文献   

月球物质的Re-Os同位素组成研究：对月球后期增生历史的指示     

许继峰  王桂琴  李杰  陈建林 《地球化学》2010,39(2):142-148

Re-Os同位素体系是理解月球强亲铁元素的分布规律和示踪月球的后期增生历史的重要手段。目前人们对月球物质Re-Os同位素成分的了解还是十分有限的,已有的Re-Os同位素数据显示一些能代表月幔成分特征的月海玄武岩具有很低的Re和Os的浓度,以及类似于球粒陨石的187Os／188Os成分特征,而月球火山玻璃和月壤等表现出相对高的Re-Os丰度和相对富放射成因Re-Os同位素成分。一般认为月球月幔的Re、0s和其他强亲铁元素相对球粒陨石是非常亏损的,而地球地幔则具有相对较高的强亲铁元素丰度（0．008倍CI球粒陨石的丰度）。新的Re-Os同位素结果证明月幔确实是亏损的,但是月球和地球在太阳系演化的较晚时期都有外来的球粒陨石物质的大量加入,即后期增生（late accretion）过程,导致了月球和地球上部物质（如月球火山玻璃、月壤等）相对地富集Os同位素和强亲铁元素,这些外来物质的后期增生可能是长期和持续的,增生过程主要发生在3．9～4．4Ga。但目前仍不清楚后期增生的陨石物质是被逐渐加入的,还是在一个相对较短的时期大量加入的,因此尚需对更多的月球物质做进一步的Re-Os同位素和强亲铁元素成分的研究。  相似文献