共查询到19条相似文献，搜索用时 241 毫秒
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王思潮 《矿物岩石地球化学通报》1985,(4)
宁强陨石于1983年6月25日19时许陨落在陕西省宁强县燕子砭乡。这是我国首次收集到的碳质球粒陨石。这种陨石是更原始的陨石,它们含有太阳星云坍缩、凝聚直至形成行星状天体的重要信息,甚至还保存有太阳系原始物质来源的记录。近十多年来,国际上对这类陨石的研究取得了多项重要成果,对太阳系起源理论有较大的参考价值。宁强陨石一共落下四块,其中最大的一块陨石落在潘家坝村安家山,陨落点的地理座标为东经105°54’4。北纬32°55’5。其他三块分别陨落在潘家坝村张家合、青岗坪村院子坝和 相似文献
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1976年9月13日下午4时40分左右在贵州西部十八个县境内上空发现有明亮火球高速飞过和降落,并在清镇县卫城区找到两块石陨石。根据贵州省科委的指示和中国科学院贵阳地球化学研究所党委的决定,迅速组成了贵州西部陨石雨考察队,并分成11个调查组于9月15日到9月31日分赴各有关县进行现场调查,共调查了94个点,被访人数达744人(其中包括目睹者144人)。在调查过程中得到当地县、区和公社领导以及广 相似文献
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吉林陨石雨陨落面积近500平方公里(图1),搜集到陨石150余块,重近2700公斤,获得世界上最大的石陨石标本(吉林Ⅰ号陨石重1770公斤)。(照片1、2)。吉林陨石雨的陨石分布,由西而东在宏观上反映出一定的规律性:1.陨石标本由西而东,体积(或重量)逐渐减小(或少);2.陨石表面的气印由极发育到不发育直到极不发育,表面只有定向明显的流纹线;3.陨石表面由平滑到粗糙;4.陨石熔壳由厚变薄。 相似文献
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世界历史上一次罕见的陨石雨 总被引：1，自引：0，他引：1
中国科学院吉林陨石雨联合考察组 《地球化学》1976,(2):157-159
今年三月八日，在我国吉林省吉林地区降落了一场空前规模的陨石雨，这是中外科学史上的一次重大事件。 相似文献
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《地球化学》1978,(3):197-201
大量石陨石的K-Ar年龄测定表明其年龄值一般要低于陨石母体的形成年龄，它反映了陨石的气体保留年龄。因此根据K—Ar年龄可以研究陨石母体与陨石的受热历史。陨石中Ar^38含量的测定可以提供陨石受宇宙射线辐射的时间标度。吉林陨石是目前世界上发现的最大的球粒陨石，因而通过对气体保留年龄和宇宙射线暴露年龄研究将为进一步了解球粒陨石的成因与演化史提供重要的资料。本文除对吉林陨石雨的Ⅴ号、Ⅱ号、Ⅰ号陨石进行测定研究外，还对其他三块在我国降落的球粒陨石进行了对比研究。根据球粒陨石的有关资料，我们对吉林陨石的受热历史和母体环境作了分析，并讨论了宇宙空间球粒陨石的形成与消失过程。 相似文献
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据统计,我国现已收集27次石陨石及24次铁陨石(图1)。如图1所示我国陨石的分布与人口密度出现正比关系。石陨石多为普通球粒陨石,其中最大的为吉林陨石雨,共收集到约2500公斤样品。铁陨石中最大的是新疆铁陨石,重约30吨,按其重量居世界第三位。 本文的主要目的是根据已发表的部分资料和笔者的室内工作,对我国部分球粒陨石的物质成分、化学-岩石类型及其形成和演化历史进行初步探讨。 相似文献
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《吉林大学学报(地球科学版)》1976,(3)
一九七六年三月八日,在吉林省吉林地区降落了一场空前规模的石陨石雨,这是中外科学史上的一个重大事件。 陨石雨降落后,吉林地区广大群众和干部立即进行了准确、详细的观测和记录。中国科学院、吉林省、吉林市联合考察组也迅速奔赴现场,在广大群众的密切配合下,搜集了丰富的资料,开展了陨石雨的研究工作。在此基础上,我们长春地质学院和吉林省 相似文献
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G. Suresh S. H. Wankhade Mohamed Shareef Vivek P. Malviya Binod Kumar M. Mohan 《Journal of the Geological Society of India》2013,81(2):151-157
A meteorite shower occurred in Katol (21° 15′ 30″ N; 78° 35′ 00″ E; at an elevation of 415 m above msl), Nagpur district of Maharashtra state, India on May 22, 2012 between 14:00 to 14:30 hrs (Indian Standard Time) with a presently observed strewn field of ～5.0 sq km area. The event was experienced by the hundreds of inhabitants with a loud noise and fire ball between Akola in the west to Nagpur in the east. The Geological Survey of India has so far collected 27 meteorite pieces with a total weight of 3500 gm. The locations, size, shape and surface features of the individual meteorite pieces have been recorded. Based on their physical properties, mineralogy, mineral chemical mapping and REE chemistry, the Katol meteorites have been classified as olivine-rich H5 type differentiated stony meteorite with reconstituted chondrules. The preliminary evidence suggests the presence of pre-solar grains in Katol meteorite. 相似文献
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V. A. Alexeev 《Geochemistry International》2012,50(8):649-656
Based on the analysis of data in [1, 2] on the concentrations of noble gases and the cosmic ray exposure age (CREA) of chromite grains in fossil meteorites, it was demonstrated in [3] that the distributions of gas concentrations and cosmic ray exposure ages can be explained under the assumption of the fall of a single meteorite in the form of a meteorite shower in southern Sweden less than 0.2 Ma after the catastrophic destruction of the parental body (asteroid) of L chondrites in space at approximately 470 Ma. This assumption differs from the conclusion in [1, 2, 4] about the long-lasting (for 1–2 Ma) delivery of L chondrites to the Earth, with the intensity of the flux of this material one to two orders of magnitude greater than now. The analysis of newly obtained data on samples from the Brunflo fossil meteorite [5] corroborates the hypothesis of a meteorite shower produced by the fall of a single meteorite. The possible reason for the detected correlations between the cosmic ray exposure ages of meteorites and the masses of the samples with the 20Ne concentrations can be the occurrence of Ne of anomalous isotopic composition in the meteorites. 相似文献
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Two meteor events which were sighted in the Gujarat skies of India, were accompained by the visibility of sporadicE ionization on the ionograms recorded at Ahmedabad (Geog. Lat. 23·2°N, long. 72·30°E). The first event was the Dhajala fireball
which flashed into the geoatmosphere along an E-N to W-S trail at about 20·40 h IST on 28 January 1976; the closest distance
of the ground projection of meteor trail from Ahmedabad was 50km. The other event was a possible meteor group sighted over
Ahmedabad on 28 May 1978, at about 21·10 h IST. This work describes the nature of the sporadicE ionization observed on Ahmedabad ionograms during the two events. Features of theEs echo during the Dhajala event which indicate that it could be of meteoric origin are discussed. Meteor theory is used to
relate the observed ionization with the physical dimensions of the Dhajala meteorite as obtained by other workers. 相似文献
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《International Geology Review》2012,54(1):8-19
On 30 June 1908, the Tunguska meteorite fell near the Podkamennaya (Stony) Tunguska River in Evenkysky National District (60°55' N. 100°57' E. ), at 11 seconds past 0017 hours Mean Greenwich Time. Eyewitnesses reported a bolide flight from southeast to northwest, followed by a violent explosion. Seismic and acoustical phenomena were reported over an area from several hundred to a thousand kilometers radius. Night-sky illumination, occurring throughout the area from mid-June gradually diminishing until its final disappearance in late August, was attributed to meteoric dust particles suspended in the atmosphere as a result of the explosion. On the Irkutsk magnetic and weather station seismograph, the impact registered as two waves (1. 2 meter amplitude) arriving approximately 5 minutes apart. Travel time from point of impact to station 893 kilometers distant, was computed at 24 hours 17 minutes 11 seconds; and wave velocity, at 330 meters per second. These and explosion-velocity data have been used in attempts to establish initial (approach) velocity and trajectory of the meteor with respect to earth movement. Investigation of the meteorite fall site began nineteen years after the meteorite fell to earth: L. A. Kulik led the first expedition to the fall site in 1927; and subsequent expeditions (undertaken by the U. S. S. R. Academy of Sciences) in 1928, in 1929-1930, and in 1939. In 1929, a geodetic section directed by S. Ya. Belych established three astro-radio points in the area. Aerial photographs were taken of the fall site during the 1929 expedition. Topographic features possibly indicating meteoric impact had been obscured by action of frost, standing water, and Sphagnum moss overgrowth in an area of permanently frozen (permafrost) mud. Phenomena caused by the explosion, e. g. orientation of uprooted trees, were used to locate the fall site during the first expedition. During a subsequent expedition, two holes were drilled in a craterlike formation (Suslov crater) on the site. Although no meteorite fragments have been found, an expedition was planned for 1958 to search for fragments at the fall site and to the southeast, along the trajectory. Other investigations will include observation and study of topographic effects on shock-wave expansion, and more accurate contouring the area relief. --D. D. Fisher. 相似文献
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There is a long-standing controversy of what triggered the extinction at the Permian-Triassic boundary, the most severe mass extinction in the geologic record, including flood basaltic volcanism and/or bolide impact hypothesis. In order to clarify various pieces of evidence for the mass extinction event at the Permian-Triassic boundary, some researchers from some laboratories throughout the world have made a comprehensive study on a group of samples from the Meishan area of China. Some fresh core samples from the Permian-Triassic boundary in the Meishan area were analyzed in this study. The results showed that there is no Ir anomaly, Moreover, the PGEs patterns of those samples show obvious differentiation characteristics, that is different from the case encountered in meteorites. So no evidence supports the hypothesis of extraterrestrial impact. In contrast, the PGEs patterns are similar to those of Siberian and Emeishan basalts, which indicates that those PGEs are derived mainly from the basalts, lending a support to the correlation between mass extinction at the Permian-Triassic boundary and flood basaltic volcanism. This study has also confirmed the results for samples from section C prior to the analysis of the samples. 相似文献
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Based on structural observations and the concentrations of Cr, Co, Ni, Cu, Ga, Ge, As, Sb, Re, Ir, and Au by neutron-activation analysis we have classified 14 Chinese iron meteorites. Thirteen are members of the large groups IAB, IIICD, IIIAB and IVA. Leshan is an ungrouped iron meteorite that falls within the IIE field on some element-Ni diagrams, but is distinctly outside this field on plots of Cu, W, and Ir vs. Ni; it is very similar in composition to Techado, another ungrouped iron. The high Cu content of Leshan in consistent with other evidence indicating that Cu is a valuable parameter for classifying iron meteorites. IIICD Dongling appears not to be a new meteorite, but to be paired with Nantan; Dongling was recovered about 50 km from the location of the Nantan shower. In view of the fact that Yongning is highly oxidized, we assign it to group IAB but cannot rule out IIICD. IVA-An Longchang has many characteristics of IVA irons, but has been remelted, probably in a terrestrial setting. Five irons belong to group IVA, a remarkably large number. Three are identical in composition, and we suspect that the two from Hubei, Guanghua and Huangling, are paired. Thus this set of 14 irons includes 12 independent falls. 相似文献
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Carol Molinivelsko Toshiko K. Mayeda Robert N. Clayton 《Geochimica et cosmochimica acta》1986,50(12):2719-2726
Samples of bulk meteorites show only mass-dependent fractionation of silicon isotopes. No isotopic anomalies were found. The variation of the ratios 29Si/28Si and 30Si/28Si over the meteorite classes is small; 1%. per mass unit difference. The average Si isotopic composition for each class of meteorites is identical, within analytical uncertainties. This is quite unlike O, whose anomalous isotopic abundances in bulk samples differentiate among the classes of meteorites. The overlapping abundance ranges of Si isotopes among many classes of meteorites suggest closed-system behavior for this element prior to meteorite accretion and allow calculation of an average solar system Si isotope composition. 相似文献