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Analysis of ablation debris from natural and artificial iron meteorites
M. B. Blanchard,A. S. Davis +1 more
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Artificial ablation studies were performed on iron and nickel-iron samples using an arc-heated plasma of ionized air as mentioned in this paper, where the outer margin of the melted rind is oxidized and recrystallizes as a discontinuous crust of magnetite and wustite.Abstract:
Artificial ablation studies were performed on iron and nickel-iron samples using an arc-heated plasma of ionized air. Experiment conditions simulated a meteoroid traveling about 12 km/sec at an altitude of 70 km. The artificially produced fusion crusts and ablation debris show features very similar to natural fusion crusts of the iron meteorites Boguslavka, Norfork, and N'Kandhla and to magnetic spherules recovered from Mn nodules. X-ray diffraction, electron microprobe, optical, and scanning electron microscope analyses reveal that important mineralogical, elemental, and textural changes occur during ablation. Some metal is melted and ablated. The outer margin of the melted rind is oxidized and recrystallizes as a discontinuous crust of magnetite and wustite. Adjacent to the oxidized metallic ablation zone is an unoxidized metallic ablation zone in which structures such as Widmannstatten bands are obliterated as the metal is transformed to unequilibrated alpha 2 nickel-iron. Volatile elements are vaporized and less volatile elements undergo fractionation.read more
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Meteoroid ablation spheres from deep-sea sediments
TL;DR: The authors examined magnetically extracted spheres from mid-Pacific abyssal clays that are up to half a million years old and classified them into three groups using their dominant mineralogy: iron, glassy, and silicate.
Journal ArticleDOI
Experimental simulation of atmospheric entry of micrometeorites
TL;DR: In this paper, the formation of a magnetite shell around most micrometeorites, which can not be reproduced, neither theoretically nor experimentally, has been investigated, and it is possible to estimate the atmospheric entry conditions of micromite entry conditions, such as the peak temperature and the duration of flash-heating.
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Extraterrestrial platinum group nuggets in deep-sea sediments
TL;DR: A previously unrecognized property of iron cosmic spheres is reported in this article, which is that the most common spheres larger than 300 microns do not, in fact, contain FeNi metal cores, but instead contain a micrometer-sized nugget composed almost entirely of platinum group elements.
Journal ArticleDOI
Silicate spherules from deep-sea sediments: confirmation of extraterrestrial origin.
TL;DR: One silicate spherule has been identified as definitely extraterrestrial since its abundances of nonvolatile trace elements closely match those of primitive solar system material.
Journal ArticleDOI
Extraterrestrial spherules in glacial sediment from the Transantarctic Mountains, Antarctica - Structure, mineralogy, and chemical composition
Christian Koeberl,Erik H. Hagen +1 more
TL;DR: The morphological, mineralogical, and chemical characteristics of silicate and glassy spherules from a number of new localities in the Transantarctic Mountains were determined.
References
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Meteorites: Classification and Properties
TL;DR: Meteorites as Probes of processes occurring very early in the history of the solar system were used as early evidence for metamorphism by meteorites as early as 1.5 billion years ago as mentioned in this paper.
Journal ArticleDOI
Lost City meteorite: Its recovery and a comparison with other fireballs
TL;DR: In this paper, meteorite photometric and trajectory data were used to compare flight characteristics with other fireballs, including fireballs from lost city/Oklahoma and meteorite meteorites.
Journal ArticleDOI
Chemical and mineralogical compositions of cosmic and terrestrial spherules from a marine sediment
H. T. Millard,R. B. Finkelman +1 more
TL;DR: In this paper, the mineralogical and chemical compositions and the specific gravities were determined for particles in a collection of large (149-351 μ diameter), dense, magnetic spherules separated from 750 kg of Pacific red clay sediment.
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Black, magnetic spherules from Pleistocene and recent beach sands
TL;DR: Black magnetic spherules in Pleistocene and recent beach sands, investigating origin by electron microscopy as mentioned in this paper, were found in the seafloor of the Mediterranean Sea and the Indian Ocean.
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Electron Microprobe Study of Spherules from Atlantic Ocean Sediments
Richard A. Schmidt,Klaus Keil +1 more
TL;DR: Spherules from Atlantic Ocean sediments studied by electron microprobe, noting terrestrial alteration and contamination of surfaces as discussed by the authors, indicate terrestrial alteration, contamination, and surface alteration and alteration.
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