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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >Zirconium isotope evidence for incomplete admixing of r-process components in the solar nebula
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Zirconium isotope evidence for incomplete admixing of r-process components in the solar nebula

机译：锆同位素证据表明太阳星云中r过程组分未完全混合

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摘要

Isotopic anomalies in Mo and Zr have recently been reported for bulk chondrites and iron meteorites and have been interpreted in terms of a primordial nucleosynthetic heterogeneity in the solar nebula. We report precise Zr isotopic measurements of carbonaceous, ordinary and enstatite chondrites, eucrites, mesosiderites and lunar rocks. All bulk rock samples yield isotopic compositions that are identical to the terrestrial standard within the analytical uncertainty. No anomalies in ~(92)Zr are found in any samples including high Nb/Zr eucrites and high and low Nb/Zr calcium-aluminum-rich inclusions (CAIs). These data are consistent with the most recent estimates of <10~(-4) for the initial ~(92)Nb/~(93)Nb of the solar system. These exists a trace of isotopic heterogeneity in the form of a small excess of r-process ~(96)Zr in some refractory CAIs and some metal-rich phases of Renazzo. A more striking enrichment in ~(96)Zr is found in acetic acid leachates of the Allende CV carbonaceous chondrite. These data indicate that the r- and s-process Zr components found in presolar grains were well mixed on a large scale prior to planetary accretion. However, some CAIs formed before mixing was complete, such that they were able to sample a population of r-process-enriched material. The maximum amount of additional r-process component that was added to the otherwise well-mixed Zr in the molecular cloud of disk corresponds to ～0.01%.
机译：Mo和Zr的同位素异常最近已被报道用于块状球粒陨石和铁陨石，并且已经根据太阳星云中的原始核合成异质性进行了解释。我们报告了碳质，普通和顽辉陨石，纤锌矿，中铁菱铁矿和月球岩石的精确Zr同位素测量。在分析不确定性范围内，所有块状岩石样品产生的同位素组成与地面标准相同。在任何样品中都没有发现〜（92）Zr异常，包括高Nb / Zr珠光体以及高和低Nb / Zr富钙铝夹杂物（CAI）。这些数据与太阳系初始〜（92）Nb /〜（93）Nb的最新估计值<10〜（-4）相一致。这些在某些难熔CAI和Renazzo的某些富金属相中以少量r-过程〜（96）Zr的形式存在同位素异质性。在阿连德CV碳质球粒陨石的乙酸浸出液中发现了〜（96）Zr更加富集的现象。这些数据表明，在行星增生之前，太阳前颗粒中发现的r和s过程Zr组分在大范围内充分混合。但是，一些在混合之前形成的CAI才完成，因此它们能够对富含r-process的物质进行采样。添加到磁盘分子云中否则充分混合的Zr中的额外r-过程组分的最大数量相当于〜0.01％。

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