Martian poikilitic shergottites are cumulate rocks that can help advance the understanding of magmatic evolution from near the base of the crust (∼10 kbar) to near-surface conditions. Through a comprehensive petrographic and geochemical study, we aim to better understand poikilitic shergottite formation and the evolution in the martian interior. A suite of poikilitic shergottites, including Northwest Africa (NWA) 7755, NWA 11043, NWA 11065, NWA 10618 and Alan Hills (ALHA) 77005, were investigated for their major, minor, and trace element compositions of olivine-hosted melt inclusions (MI). The MI occur within both the early-evolutional stage textural and late-evolution stage textural domains in olivine. Major element compositions of MI indicate fractional crystallization between the early and late-crystallizing domains. Calculated parental melt compositions from these MI data yielded results that also petrogenetically link the poikilitic shergottites with the olivine-phyric shergottite subgroup. Trace element compositions of MI show that the later-crystallizing MI could have undergone open-system processes, such as fluid exsolution. Lutetium-Hf and Sm-Nd isotopic analyses were performed on NWA 7755 and NWA 11043 to constrain their age and source isotopic compositions. Northwest Africa 7755 shows a Lu/Hf crystallization age of 223 ± 46 Ma, which fits into the expected range for enriched shergottites of ∼165 Ma to 225 Ma. A similar crystallization age and Lu/Hf and Sm/Nd source composition of NWA 7755 to the other enriched shergottites suggest that this specimen likely shares a long-lived geochemical source with these samples that has lasted for at least 60 Ma. Northwest Africa 11043 shows scatter throughout the Lu-Hf and Sm-Nd isotopic data, suggesting that this sample is not in isotopic equilibrium. This sample was possibly inherited from high-temperature processes, such as incomplete magmas mixing from a similar, but distinct, source. We conducted in situ U-Th-Pb isotope analyses of Ca-phosphate minerals for NWA 11043 and found an unreliable crystallization age of 59.2 ± 138.4 Ma: phosphates are likely recording the period of shock metamorphism related to the ejection event. Consistent crystallization ages and magmatic histories support previous work that suggest there is a common magmatic system on Mars that is responsible for the formation of enriched shergottites.

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异质六角岩的来源和母体熔化：对火星岩浆作用的影响

火星异岩辉石是堆积岩，有助于加深对从地壳底部附近（~10 kbar）到近地表条件的岩浆演化的理解。通过全面的岩相学和地球化学研究，我们的目标是更好地了解异质硅角辉石的形成和火星内部的演化。研究了一系列异硅角辉石，包括西北非洲 (NWA) 7755、NWA 11043、NWA 11065、NWA 10618 和 Alan Hills (ALHA) 77005，研究了橄榄石熔体包裹体 (MI) 的主量、次量和微量元素组成。 ）。 MI 发生在橄榄石的早期演化阶段结构域和晚期演化阶段结构域内。 MI 的主要元素组成表明早结晶域和晚结晶域之间的分级结晶。根据这些 MI 数据计算出的母体熔体成分所得出的结果也在岩石成因上将异色角辉石与橄榄石状辉角辉石亚群联系起来。 MI 的微量元素组成表明，后来结晶的 MI 可能经历了开放系统过程，例如流体溶出。对 NWA 7755 和 NWA 11043 进行了镥-Hf 和 Sm-Nd 同位素分析，以限制其年龄和来源同位素组成。西北非洲 7755 显示 Lu/Hf 结晶年龄为 223 ± 46 Ma，符合约 165 Ma 至 225 Ma 富集的六角辉石的预期范围。 NWA 7755 的结晶年龄以及 Lu/Hf 和 Sm/Nd 源组成与其他富集的六角辉石相似，表明该样本可能与这些样品共享一个长期存在的地球化学源，持续时间至少为 60 Ma。西北非洲 11043 的 Lu-Hf 和 Sm-Nd 同位素数据显示分散，表明该样本不处于同位素平衡状态。该样本可能是从高温过程继承的，例如来自相似但不同来源的不完全岩浆混合。我们对 NWA 11043 的磷酸钙矿物进行了原位 U-Th-Pb 同位素分析，发现不可靠的结晶年龄为 59.2 ± 138.4 Ma：磷酸盐可能记录了与喷射事件相关的冲击变质作用时期。一致的结晶年龄和岩浆历史支持了之前的研究，即火星上存在一个共同的岩浆系统，它导致了丰富的六角辉石的形成。