本文選題：巖莊隕石 + 沖擊熔體��； 參考：《地球化學(xué)》2017年04期

【摘要】：巖莊隕石是受強(qiáng)烈沖擊的H群普通球粒隕石,含有厘米級(jí)寬度的熔脈和熔塊。沖擊熔體中微量元素的分布,對(duì)了解在高溫低壓下從熔體分離結(jié)晶物相的元素再分配具有重要價(jià)值。本文以巖莊隕石中的全巖熔體、硅酸鹽熔體和FeNi+FeS共結(jié)團(tuán)粒中的FeNi金屬三種物相為研究對(duì)象,利用激光剝蝕等離子體質(zhì)譜技術(shù),分別對(duì)其進(jìn)行微量元素分析。結(jié)果表明:(1)該隕石沖擊熔融后,Fe、Co和Ni等親鐵元素主要富集在全巖熔體內(nèi)的FeNi金屬相中,而Cr、V、Ti和Mn等則主要進(jìn)入從硅酸鹽熔體中晶出的微晶輝石晶格內(nèi),以置換M1位上的Al~(3+)。(2)Cu、Ga和Pb等親銅元素也大部分都富集在FeNi金屬相中,而揮發(fā)性較強(qiáng)的Zn,在隕石熔融時(shí)雖有少量丟失,但主要進(jìn)入硅酸鹽熔體相內(nèi),賦存在微晶橄欖石和輝石晶格之中以置換Fe~(2+)。(3)Sc、Zr、Nb和Ta等親石元素,基本上都賦存在硅酸鹽熔體相中,但Nb和Ta的分異程度低,而FeNi金屬相的Nb/Ta比值比硅酸鹽熔體要偏低一倍多,說明高溫高壓下隕石熔融時(shí),Nb比Ta更為活潑。(4)硅酸鹽熔體和全巖熔體的稀土元素分布均具有明顯的奇偶效應(yīng),總體呈現(xiàn)輕稀土富集,重稀土虧損的特點(diǎn),而FeNi金屬則呈現(xiàn)輕稀土相對(duì)虧損的特點(diǎn),且其稀土總量比硅酸鹽熔體低近三倍,說明稀土元素特別是輕稀土元素主要賦存在硅酸鹽熔體中。鉑族元素在隕石局部熔融后轉(zhuǎn)移到共結(jié)團(tuán)粒的FeNi金屬之中。
[Abstract]:Yanzhuang meteorite is an ordinary chondrite of group H which is strongly impacted and contains a centimeter width of veins and melts.The distribution of trace elements in impact melts is of great value in understanding the redistribution of elements in the crystallization phase separated from the melt at high temperature and low pressure.In this paper, the phases of whole rock melt, silicate melt and FeNi metal in FeNi FeS co-agglomerates in Yanzhuang meteorite were studied. The trace elements were analyzed by laser denudation plasma mass spectrometry.The results show that the Fe _ (2 +) Fe _ (2) O _ (2) and Ni are mainly enriched in the FeNi phase in the whole rock melt after impact melting, while Cr ~ (2 +) V ~ (2 +) Ti and mn mainly enter the microcrystalline pyroxene lattice from the silicate melt.The copperophile elements, such as Al~(3 ~ (2 +), Cu ~ (2 +) Ga and Pb, which are substituted at M1 site, are also mostly enriched in the FeNi metallic phase. However, the highly volatile Al~(3, which is lost in a small amount during the melting of the meteorite, mainly enters the silicate melt phase.In the microcrystalline olivine and pyroxene lattices, the lipophilic elements such as Fe~(2 ~ (3) C ~ (3) C ~ (2 +) C ~ (2 +) Zr ~ (2 +) NB and Ta are mainly found in silicate melts, but the difference between NB and Ta is low, and the Nb/Ta ratio of FeNi metallic phase is more than twice as low as that of silicate melts.The results show that the distribution of rare earth elements in silicate melts and whole rock melts is more active than Ta at high temperature and high pressure. The distribution of rare earth elements in both melts and whole rock melts is characterized by enrichment of light rare earths and depletion of heavy rare earths.The FeNi metal is characterized by the relative depletion of light rare earth elements, and the total amount of rare earth elements is nearly three times lower than that of silicate melts, indicating that rare earth elements, especially light rare earth elements, mainly occur in silicate melts.Platinum group elements are transferred to the FeNi metal of conjunctive aggregates after partial melting of the meteorite.
【作者單位】： 中國科學(xué)院礦物學(xué)與成礦學(xué)重點(diǎn)實(shí)驗(yàn)室廣東省礦物物理與材料研究開發(fā)重點(diǎn)實(shí)驗(yàn)室中國科學(xué)院廣州地球化學(xué)研究所;西北大學(xué)大陸動(dòng)力學(xué)國家重點(diǎn)實(shí)驗(yàn)室;
【基金】：國家自然科學(xué)基金(41172046)
【分類號(hào)】：P185.83

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1 李肇輝,謝先德,張大同;太空(FeNi)金屬熔體凝固的時(shí)空?qǐng)D象和結(jié)晶機(jī)理研究[J];中國科學(xué)(B輯 化學(xué) 生命科學(xué) 地學(xué));1994年03期

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