Arid
DOI10.1016/j.epsl.2008.11.020
Isotopic fractionation of zinc in tektites
Moynier, Frederic1,2; Beck, Pierre3; Jourdan, Fred4; Yin, Qing-Zhu; Reimold, Uwe5; Koeberl, Christian6
通讯作者Moynier, Frederic
来源期刊EARTH AND PLANETARY SCIENCE LETTERS
ISSN0012-821X
出版年2009
卷号277期号:3-4页码:482-489
英文摘要

Tektites are terrestrial natural glasses produced during a hypervelocity impact of an extraterrestrial projectile onto the Earth’s surface. The similarity between the chemical and isotopic compositions of tektites and terrestrial upper continental crust implies that the tektites formed by fusion of such target rock. Tektites are among the driest rocks on Earth. Although volatilization at high temperature may have caused this extreme dryness, the exact mechanism of the water loss and the behavior of other volatile species during tektite formation are still debated. Volatilization can fractionate isotopes, therefore, comparing the isotope composition of volatile elements in tektites with that of their source rocks may help to understand the physical conditions during tektite formation.


For this study, we have measured the Zn isotopic composition of 20 tektites from four different strewn fields. Almost all samples are enriched in heavy isotopes of Zn compared to the upper continental crust. On average, the different groups of tektites are isotopically distinct (listed from the isotopically lightest to the heaviest): Muong-Nong type indochinites (delta(66/64)Zn=0.61 +/- 0.30 parts per thousand); North American bediasites (delta(66/64)Zn=1.61 +/- 0.49 parts per thousand); Ivory Coast tektites (delta(66/64)Zn=1.66 +/- 0.18 parts per thousand); the Australasian tektites (others than the Muong Nong-type indochinites) (delta(66/64)Zn=1.84 +/- 0.42 parts per thousand); and Central European moldavites (delta(66/64)Zn=2.04 +/- 0.19 parts per thousand). These results are contrasted with a narrow range of delta(66/64)Zn=0-0.7 parts per thousand for a diverse spectrum of upper continental crust materials.


The elemental abundance of Zn is negatively correlated with delta(66/64)Zn, which may reflect that isotopic fractionation occurred by evaporation during the heating event upon tektite formation. Simple Rayleigh distillation predicts isotopic fractionations much larger than what is actually observed, therefore, such a model cannot account for the observed Zn isotope fractionation in tektites. We have developed a more realistic model of evaporation of Zn from a molten sphere: during its hypervelocity trajectory, the molten surface of the tektite will be entrained by viscous coupling with air that will then induce a velocity field inside the molten sphere. This velocity field induces significant radial chemical mixing within the tektite that accelerates the evaporation process. Our model, albeit parameter dependent, shows that both the isotopic composition and the chemical abundances measured in tektites can be produced by evaporation in a diffusion-limited regime. (C) 2008 Elsevier B.V. All rights reserved.


英文关键词Tektites Zn Isotopes MC-ICP-MS stable Isotope fractionation evaporation diffusion
类型Article
语种英语
国家USA ; France ; Australia ; Germany ; Austria
收录类别SCI-E
WOS记录号WOS:000263208800020
WOS关键词IVORY-COAST TEKTITES ; EXPERIMENTAL VAPOR FRACTIONATION ; BOSUMTWI IMPACT STRUCTURE ; LIBYAN DESERT GLASS ; AUSTRALASIAN TEKTITES ; TRACE-ELEMENT ; GEOCHEMISTRY ; ZN ; CONSTRAINTS ; ORIGIN
WOS类目Geochemistry & Geophysics
WOS研究方向Geochemistry & Geophysics
来源机构University of California, Davis
资源类型期刊论文
条目标识符http://119.78.100.177/qdio/handle/2XILL650/160323
作者单位1.Washington Univ, Dept Earth & Planetary Sci, St Louis, MO 63130 USA;
2.Univ Calif Davis, Dept Geol, Davis, CA 95616 USA;
3.Univ Grenoble 1, Lab Planetol, CNRS, INSU, F-38041 Grenoble, France;
4.Curtin Univ Technol, Dept Appl Geol & JdL CMS, Western Australian Agron Isotope Facil, Perth, WA 6845, Australia;
5.Univ Humberside, Museum Nat Hist Minerol, D-10115 Berlin, Germany;
6.Univ Vienna, Dept Lithospher Res, A-1090 Vienna, Austria
推荐引用方式
GB/T 7714
Moynier, Frederic,Beck, Pierre,Jourdan, Fred,et al. Isotopic fractionation of zinc in tektites[J]. University of California, Davis,2009,277(3-4):482-489.
APA Moynier, Frederic,Beck, Pierre,Jourdan, Fred,Yin, Qing-Zhu,Reimold, Uwe,&Koeberl, Christian.(2009).Isotopic fractionation of zinc in tektites.EARTH AND PLANETARY SCIENCE LETTERS,277(3-4),482-489.
MLA Moynier, Frederic,et al."Isotopic fractionation of zinc in tektites".EARTH AND PLANETARY SCIENCE LETTERS 277.3-4(2009):482-489.
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