Record of S-rich vapors on asteroid 4 Vesta: Sulfurization in the Northwest Africa 2339 eucrite.
Record of S-rich vapors on asteroid 4 Vesta: Sulfurization in the Northwest Africa 2339 eucrite.
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小行星 4 号灶神星上富硫蒸气的记录：西北非洲 2339 锂辉石的硫化。
DOI：
10.1016/j.gca.2013.01.036
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发表时间：
2013-05
影响因子：
5
通讯作者：
Bartoschewitz R.
中科院分区：
文献类型：
--
作者：
Zhang Aicheng;Wang Rucheng;Hsu Weibiao;Bartoschewitz R.
在西北非洲(NWA)2339真核岩中，少量高铁白云母碎屑被细粒硫铁矿、富镁辉石、二氧化硅部分置换，并有少量钛铁矿和富镁铁硅岩。在NWA2339的细粒交代结构和其他非晶质辉石中，残余白云母的Fe/Mn值(17-18)明显低于辉石和富镁铁硅岩的Fe/Mn值(∼30)。与这些富铁的鸽子碎屑伴生的少数斜长石颗粒含有高钠长石成分(Ab17-31)。类似的替代结构也存在于由辉石和富钠斜长石(Ab20-25)组成的岩屑碎屑中。在这一岩屑碎屑中，高铁亚钙辉石被硫铁矿、富镁铁辉石、二氧化硅和少量钛铁矿取代，而富镁鸽子岩保持不变。沸石也以微小包裹体的形式出现在斜长石的多孔区。此外，与残留的斜长石相比，斜长石的多孔区富硅，贫铝、钙和钠。这些结构表明，富硫铁石矿物组合的形成与辉石中的FeSiO_3组分与富S水蒸气的反应有关，而斜长石多孔区微细沸石的形成与斜长石中的Fe~(2+)与富S水蒸气的反应有关。X射线图谱结果表明，在辉石和斜长石的硫化过程中，亲石元素Mn、Al、Ca、Na和Mg被不同程度地去除，很可能是由富S的水蒸气造成的。根据我们的观察，富含S的蒸气可能是干燥的S-O-P蒸气，很可能是由于小行星4灶神星表面的撞击加热而挥发了先前存在的S含磷物质而形成的。
In the Northwest Africa (NWA) 2339 eucrite, a few high-Fe pigeonite fragments were partially replaced by fine-grained troilite, Mg-rich augite, silica, with minor ilmenite and Mg-rich ferrosilite. The relict pigeonite has distinctly lower Fe/Mn values (17–18) than those (∼30) of augite and Mg-rich ferrosilite in the fine-grained replacement textures and other eucritic pyroxenes in NWA 2339. The few plagioclase grains associated with these Fe-rich pigeonite fragments contain high albite components (Ab17–31). Similar replacement textures are also present in a lithic clast consisting of pyroxene and Na-rich plagioclase (Ab20–25). In this lithic clast, high-Fe subcalcic augite was replaced by troilite, Mg-rich hedenbergite, silica, and minor ilmenite whereas Mg-rich pigeonite remains intact. Troilite also occurs as tiny inclusions in porous regions of plagioclase. Moreover, the porous regions of plagioclase are enriched in Si and depleted in Al, Ca, and Na, compared to relict plagioclase. These textures indicate that the formation of troilite-rich mineral assemblages is related to the reaction between FeSiO3component in pyroxene and S-rich vapors; whereas, the formation of tiny troilite in porous regions of plagioclase is related to the reaction between Fe2+in plagioclase and S-rich vapors. X-ray mapping results reveal that during sulfurization of pyroxene and plagioclase, lithophile elements Mn, Al, Ca, Na, and Mg were removed to various extents, very likely by the S-rich vapors. Based on our observations, the S-rich vapors could be dry S–O–P vapors, which most likely have been formed by volatilization of pre-existing S,P-bearing materials due to impact heating on the surface of asteroid 4 Vesta.
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影响因子：
2.2
作者：
P. Buchanan;D. Lindstrom;D. Mittlefehldt;C. Koeberl;W. U. Remold
通讯作者：
P. Buchanan;D. Lindstrom;D. Mittlefehldt;C. Koeberl;W. U. Remold
影响因子：
5
作者：
TOULMIN, P;BARTON, PB
通讯作者：
BARTON, PB
影响因子：
5
作者：
R. Mayne;H. McSween;T. Mccoy;A. Gale
通讯作者：
R. Mayne;H. McSween;T. Mccoy;A. Gale
影响因子：
--
作者：
J. Papike
通讯作者：
J. Papike
影响因子：
5.2
作者：
S. Hasegawa;K. Murakawa;M. Ishiguro;Hidenori Nonaka;N. Takato;C. Davis;M. Ueno;T. Hiroi
通讯作者：
S. Hasegawa;K. Murakawa;M. Ishiguro;Hidenori Nonaka;N. Takato;C. Davis;M. Ueno;T. Hiroi