GEMS (glass with embedded metal and sulfides) are the dominant carrier of amorphous silicates in anhydrous interplanetary dust particles (IDPs) and one of the most suitable materials to study early solar system processes. Amorphous silicates in 105 GEMS from eight IDPs were analyzed regarding texture and chemical composition to reassess GEMS formation theories and genetic relationships to amorphous silicate material in meteorites. Petrography of bulk IDPs was investigated to understand GEMS’ relationships to other IDP components. Furthermore, carbon and nitrogen isotopic compositions were measured. Nearly all GEMS are aggregates of several subgrains with variable amount of nanophase inclusions and different Mg- and Si-contents, while single GEMS are rare. The subgrains within aggregates are typically surrounded by one or more carbon rims with high density. The chemical compositions of GEMS amorphous silicates are subsolar for all major element/Si ratios but exhibit wide heterogeneity. This is not influenced by silicon oil from the capturing process of IDPs as assumed before, as a penetration of the silicon oil is excluded by high resolution EELS (electron energy loss spectroscopy) areal density maps of silicon. Furthermore, low Fe-content in GEMS amorphous silicates shows that these are not altered by aqueous activity on the parent body as it is the case for amorphous silicate material in primitive meteorites. The subsolar element/Si ratios and the wide chemical heterogeneity point to a non-equilibrium fractional condensation origin either in the early solar nebula or in a circumstellar environment and are not in agreement with homogenization via sputtering in the ISM. The close association with carbon around GEMS subgrains and as double-rims around GEMS aggregates argue for a multi-step aggregation after formation of the smallest GEMS subgrains in the ISM or the early solar nebula. Carbon acting as matrix material connecting GEMS and other IDP components has lower areal density as seen from carbon EELS areal density maps and isotopic anomalies varying at the nanometer scale, pointing to different origins and processing of materials to varying extent or at changing temperatures.

中文翻译：

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彗星 IDP 及其 GEMS 无定形硅酸盐的岩相和化学特征以及碳和氮同位素组成


GEMS（嵌入金属和硫化物的玻璃）是无水行星际尘埃粒子（IDP）中无定形硅酸盐的主要载体，也是研究早期太阳系过程的最合适材料之一。对来自 8 个 IDP 的 105 个 GEMS 中的非晶硅酸盐进行了结构和化学成分分析，以重新评估 GEMS 形成理论以及与陨石中非晶硅酸盐材料的遗传关系。对散装 IDP 的岩相学进行了研究，以了解 GEMS 与其他 IDP 成分的关系。此外，还测量了碳和氮同位素组成。几乎所有的 GEMS 都是几种亚晶的聚集体，具有不同数量的纳米相夹杂物和不同的 Mg 和 Si 含量，而单一的 GEMS 很少见。聚集体内的亚晶粒通常被一个或多个高密度碳环包围。 GEMS 无定形硅酸盐的化学成分对于所有主要元素/Si 比率而言均低于太阳光，但表现出广泛的异质性。这不受之前假设的 IDP 捕获过程中的硅油的影响，因为硅油的渗透被硅的高分辨率 EELS（电子能量损失光谱）面密度图排除。此外，GEMS 无定形硅酸盐中的低铁含量表明，它们不会像原始陨石中的无定形硅酸盐材料那样因母体上的水活动而改变。太阳下​​元素/硅比率和广泛的化学异质性表明早期太阳星云或星周环境中存在非平衡部分凝结起源，并且与ISM中通过溅射实现的均质化不一致。 与 GEMS 亚颗粒周围的碳以及 GEMS 聚集体周围的双环的密切联系表明，在 ISM 或早期太阳星云中最小的 GEMS 亚颗粒形成后会发生多步骤聚集。从碳 EELS 面密度图和纳米尺度变化的同位素异常来看，作为连接 GEMS 和其他 IDP 组件的基质材料的碳具有较低的面密度，表明不同程度或在变化的温度下材料的不同来源和加工。