Abstract Acapulcoites-lodranites, ureilites, brachinites, brachinite-like achondrites and winonaites are the main groups of primitive achondrites. They are variably depleted in incompatible lithophile elements (Al, Na, K and rare earth elements) and siderophile/chalcophile elements relative to chondrites and are interpreted as the residual mantle of planetesimals from which silicate melts and sulfide/metal melts were extracted. We use a series of melting experiments conducted with various chondritic compositions (CV, CM, CI, H and LL) to constrain the oxygen fugacity (fO2), the temperature, extent of melting and the initial bulk composition of the parent bodies of primitive achondrites. They melted at different and variable fO2: ΔIW −0.5/−1.0 for brachinites, ΔIW −1.3/−2.5 for ureilites, ΔIW −1.6/−2.7 for acapulcoites/lodranites and ΔIW −2.5/−3.0 for winonaites (with ΔIW = log fO2 – (log fO2)IW; IW being the iron-wustite buffer). Those main groups of primitive achondrites, which have nucleosynthetic anomalies characteristic of the “non-carbonaceous” reservoir and the inner solar system, were not initially depleted in Na2O and K2O relative to the sun’s photosphere. This suggests, in accordance with the enrichment in the heavy isotopes of Zn, Rb and K in eucrites, that the depletion of moderately volatile elements in planetesimals that melted to a larger extent (e.g. Vesta, the angrite parent body) resulted from evaporative losses during partial melting. The depletion of moderately volatile elements in terrestrial planets is likely inherited from partial melting and differentiation of small planetary bodies rather than from the incomplete condensation of the solar nebula.

中文翻译：

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太阳系内未耗尽碱金属的小行星部分熔融形成原始无球粒陨石

摘要 Acapulcoites-lodranites、ureilites、brachinites、类brachinite无球粒陨石和winonaites是原始无球粒陨石的主要类群。相对于球粒陨石，它们在不相容的亲石元素（Al、Na、K 和稀土元素）和亲铁/亲硫元素中不同程度地耗尽，并被解释为微行星的残余地幔，从中提取硅酸盐熔体和硫化物/金属熔体。我们使用一系列用各种球粒陨石成分（CV、CM、CI、H 和 LL）进行的熔融实验来约束原始无球粒陨石母体的氧逸度 (fO2)、温度、熔融程度和初始体积成分. 它们在不同且可变的 fO2 下熔化：对于腕石的 ΔIW -0.5/-1.0，对于 ureilites 的 ΔIW -1.3/-2.5，对于 acapulcoites/lodranites 的 ΔIW -1.6/-2.7 和 ΔIW -2.5/-3。Winonaites 为 0（ΔIW = log fO2 – (log fO2)IW；IW 是铁-方氏体缓冲液）。这些主要的原始无球粒陨石群具有“非碳质”储层和内部太阳系的核合成异常特征，相对于太阳光球层，它们最初并未耗尽 Na2O 和 K2O。这表明，根据 Zn、Rb 和 K 重同位素在晶石中的富集，熔融程度较大的星子（例如灶神星，Angrite 母体）中中度挥发性元素的消耗是由于蒸发过程中的蒸发损失造成的。部分熔化。类地行星中挥发性元素的消耗很可能是由于小行星体的部分熔化和分化，而不是太阳星云的不完全凝聚。