Petrogenetic relationships among members of the brachinite family were established by analyzing major and trace element concentrations of minerals for 9 representative specimens: Al Huwaysah 010, Eagles Nest, Northwest Africa (NWA) 4882, NWA 5363, NWA 7297, NWA 7299, NWA 11756, Ramlat as Sahmah (RaS) 309, and Reid 013. The brachinite family, which includes brachinites and ungrouped achondrites with compositional and isotopic similarities to brachinites, comprises FeO‐rich, olivine‐dominated achondrites whose compositional and mineralogic variability is correlated with oxidation state. Most classical brachinites are derived from precursors that were more oxidized and sulfur‐rich than those of ungrouped “brachinite‐like” achondrites. This is manifest in the distinct Fe‐Ni‐S systems among brachinite family precursors, which were sulfide‐dominated for the most oxidized brachinites and metal‐dominated for the least oxidized brachinite‐like achondrites. Consequently, highly siderophile element behavior was controlled through melting and removal of their dominant host phase in the precursor, which was likely pentlandite in sulfide‐dominated systems and kamacite/taenite in metal‐dominated systems. Anomalous Ir/Os and Pt/Os ratios of oxidized brachinites may be attributed to selective complexing during melting of As‐rich pentlandite, consistent with our observations of impact‐melted sulfides in R chondrite NWA 11304, although further experimental work is needed to model this process. The apparent redox trend among the brachinite family is consistent with silicate FeO content and Fe/Mn ratios, which may be used as a proxy for determining the relative oxidation state of brachinite family members. Based on our analyses, we make several recommendations for reclassification of samples into a continuum of oxidized to reduced endmembers for the brachinite family. Along with a common range of Δ¹⁷O, this evidence is consistent with either formation on a common heterogeneous parent body, or at least from the same nebular reservoir, with variable O and S fugacities, resulting in mineralogically distinct igneous products for oxidized and reduced endmembers. Sulfur‐bearing, oxidized differentiation may extend to other bodies that formed at or beyond the snow line in the early solar system, and should be considered when interpreting observational data for asteroids in upcoming missions.

中文翻译：

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铁矿中硫化物为主的部分熔融途径

通过分析9个代表性标本的矿物质的主要和微量元素含量，建立了Brachite家族成员之间的岩石遗传关系：Al Huwaysah 010，Eagles Nest，西北非洲（NWA）4882，NWA 5363，NWA 7297，NWA 7299，NWA 11756， Ramlat为Sahmah（RaS）309和Reid013。含Brachuite和与Braschite组成和同位素相似的未成群的长晶石的Brachuite族包括富FeO的，橄榄石为主的长晶石，其组成和矿物学变异性与氧化态相关。大多数经典的铁锰矿均来自前体，这些前体比未分组的“铁锰矿样”长晶石更易被氧化和富硫。这体现在铁锰矿前体中独特的Fe-Ni-S系统中，对于氧化程度最高的Brachite，硫化物占主导地位；对于氧化程度最低的Brachite-like角铁矿晶，金属占主导地位。因此，高度熔融金属元素的行为是通过熔化和除去其前体中的主要主体相来控制的，这在硫化物占主导地位的系统中可能是膨润土，而在金属占主导地位的系统中可能是钾长石/钙钛矿。氧化铍晶石的Ir / Os和Pt / Os比率异常可能归因于富砷五方铁矿熔融过程中的选择性络合，这与我们对R球粒陨石NWA 11304中冲击熔融硫化物的观察结果一致，尽管需要对此进行建模的进一步实验工作处理。球铁矿族之间的明显氧化还原趋势与硅酸盐中FeO含量和Fe / Mn比一致，可以用作确定铁锰矿家族成员相对氧化态的代表。根据我们的分析，我们提出了一些建议，以将样品重新分类为硬铁矿家族的氧化至还原端基​​的连续体。伴随着Δ的共同范围^在17 O中，该证据与在同一个异质母体上形成或至少从相同的神经元储层中形成，具有可变的O和S逸出相符，从而导致了矿物学上不同的火成产物，用于氧化和还原的端基。含硫，氧化的分化可能会扩展到在早期太阳系中雪线处或超出雪线形成的其他物体，在解释即将进行的任务中小行星的观测数据时应予以考虑。