Abstract Lunar samples collected during Apollo missions are typically impact-related breccias or regolith that contain amalgamations of rocks and minerals with various origins (e.g., products of igneous differentiation, mantle melting, and/or impact events). The largest intact pre-Nectarian (∼≥3.92 Ga) fragments of igneous rock contained within the breccia and regolith rarely exceed 1 cm in size, and they often show evidence for impact recrystallization. This widespread mixing of disparate materials makes unraveling the magmatic history of pre-Nectarian period fraught with challenges. To address this issue, we combine U-Pb geochronology of Apollo 14 zircons (207Pb–206Pb ages from 3.93 to 4.36 Ga) with zircon trace element chemistry and thermodynamic models. Zircon crystallization temperatures are calculated with Ti-in-zircon thermometry after presenting new titania and silica activity models for lunar melts. We also present rare earth element (REE), P, actinide, and Mg + Fe + Al concentrations. While REE patterns and P yield little information about the parent melt origins of these out-of-context grains, U and Th concentrations are highly variable among pre-4.2 Ga zircons when compared to younger grains. Thus, the distribution of heat-producing radioactive elements in melt sources pervading the early lunar crust was heterogenous. Melt composition variation is confirmed by zircon Al concentrations and thermodynamic modeling that reveal at least two dominant magma signatures in the pre-4.0 Ga zircon population. One inferred magma type has a high alumina activity. This magma likely assimilated anorthosite-rich rocks (e.g., Feldspathic Highlands Terrane; FHT), though impact-generated melts of an alumina-rich target rock is a viable alternative. The other magma signature bears more similarities to KREEP basalts from the Procellarum KREEP Terrane (PKT), reflecting lower apparent alumina activities. Melt diversity seems to disappear after 4.0 Ga, with zircon recording magma compositions that largely fall in-between the two main groups found for pre-4.0 Ga samples. We interpret

中文翻译：

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来自锆石化学的各种月球熔体成分和 3.9 Ga 之前地壳混合的证据

摘要 阿波罗任务期间收集的月球样本通常是与撞击相关的角砾岩或风化层，其中包含具有各种来源的岩石和矿物（例如，火成岩分化、地幔熔化和/或撞击事件的产物）的混合物。包含在角砾岩和风化层中的最大完整的前酒水纪 (~≥3.92 Ga) 火成岩碎片的尺寸很少超过 1 厘米，并且它们经常显示出撞击再结晶的证据。不同材料的这种广泛混合使得解开前酒水纪时期的岩浆历史充满挑战。为了解决这个问题，我们将阿波罗 14 号锆石的 U-Pb 年代学（207Pb-206Pb 年龄从 3.93 到 4.36 Ga）与锆石微量元素化学和热力学模型相结合。在为月球熔体提供新的二氧化钛和二氧化硅活性模型后，锆石结晶温度是用锆石中钛温度计计算的。我们还提供了稀土元素 (REE)、P、锕系元素和 Mg + Fe + Al 浓度。虽然 REE 模式和 P 几乎没有关于这些背景外晶粒的母体熔体起源的信息，但与年轻晶粒相比，U 和 Th 浓度在 4.2 Ga 之前的锆石中变化很大。因此，早期月球地壳的熔体源中产热放射性元素的分布是不均匀的。熔体成分的变化通过锆石 Al 浓度和热力学模型得到证实，这些模型揭示了 4.0 Ga 之前的锆石群体中至少有两个主要的岩浆特征。一种推断的岩浆类型具有高氧化铝活性。这种岩浆可能同化了富含斜长岩的岩石（例如，Feldspathic Highlands Terrane；FHT），尽管撞击产生的富含氧化铝的目标岩石熔体是一个可行的选择。另一个岩浆特征与来自 Procellarum KREEP Terrane (PKT) 的 KREEP 玄武岩有更多相似之处，反映了较低的表观氧化铝活动。熔体多样性似乎在 4.0 Ga 之后消失，锆石记录的岩浆成分主要介于 4.0 Ga 之前的样品中发现的两个主要组之间。我们解读 0 Ga，锆石记录的岩浆成分主要介于为 4.0 Ga 之前的样品发现的两个主要组之间。我们解读 0 Ga，锆石记录的岩浆成分主要介于为 4.0 Ga 之前的样品发现的两个主要组之间。我们解读