Young lunar mare basalts in the Chang'e-5 sample return region, northern Oceanus Procellarum
Young lunar mare basalts in the Chang'e-5 sample return region, northern Oceanus Procellarum
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DOI：
10.1016/j.epsl.2020.116702
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发表时间：
2021-02-01
影响因子：
5.3
通讯作者：
Wilson, Lionel
中科院分区：
文献类型：
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作者：
Qian, Yuqi;Xiao, Long;Wilson, Lionel
嫦娥五号是中国首次月球采样返回任务，目标是在 Procellarum 北部着陆，该区域的选择基于以下因素：1) 其位置远离阿波罗-月球采样区；2) Procellarum 克里普地体 (PKT) 的存在；3) 存在最年轻的月海玄武岩 (Em4)；4) 与 Rima Sharp 的关联。为了为返回的样本分析提供背景，我们对 Em4 月海玄武岩的区域和全球环境、地貌、成分、矿物学和年代学进行了全面研究。 Em4 叠加在雨纪年龄的低钛玄武岩上，覆盖 37,000 km(2)，由爱拉托逊纪年龄（约 1.53 Ga）高钛玄武岩组成，平均厚度约 51 m，体积约在 1450 至 2350 km(3) 之间。单元内 TiO2 和 FeO 丰度存在微小变化，钍含量平均值类似于 6.7 ppm，这是 PKT 海洋玄武岩风化层的典型特征。装置内未发现特定的源排放口（例如裂缝、锥体、圆顶）。我们表明，Rima Sharp 实际上由三个主要细沟组成，其源喷口位于 Em4 外部，流入并合并于 Em4，表明它们可能是 Em4 的源头之一。风化层厚度平均约为 7 m，并且有大量证据表明存在垂直和横向混合；远端喷射物最可能的来源是阿里斯塔克斯陨石坑、哈帕勒斯陨石坑和夏普 B 陨石坑。因此，从撞击产生的本地和遥远物质中返回的样本将为月球地质年代学、内太阳系撞击通量、非常年轻的月海玄武岩的年龄、PKT在月海玄武岩生成中的作用、蜿蜒的细沟在熔岩流就位中的作用以及月球的热演化提供重要的新见解。 (C) 2020 Elsevier B.V. 保留所有权利。
Chang'e-5, China's first lunar sample return mission, is targeted to land in northern Oceanus Procellarum, within a region selected on the basis of 1) its location away from the Apollo-Luna sampling region, 2) the presence of the Procellarum KREEP Terrane (PKT), 3) the occurrence of one of the youngest lunar mare basalts (Em4), and 4) its association with Rima Sharp. In order to provide context for returned sample analyses, we conducted a comprehensive study of the regional and global settings, geomorphology, composition, mineralogy, and chronology of the Em4 mare basalts. Superposed on Imbrian-aged low-Ti basalts, Em4 covers 37,000 km(2) and is composed of Eratosthenian-aged (similar to 1.53 Ga), high-Ti basalts with a mean thickness of similar to 51 m and a volume between similar to 1450 and 2350 km(3). Minor variations in TiO2 and FeO abundance occur within the unit and the thorium content averages similar to 6.7 ppm, typical of PKT mare basaltic regolith. No specific source vents (e.g., fissures, cones, domes) were found within the unit. We show that Rima Sharp is actually composed of three major rilles, whose source vents are located outside of, and which flow into, and merge in Em4, suggesting that they may be among the sources for Em4. Regolith thickness averages similar to 7 m and there is abundant evidence for vertical and lateral mixing; the most likely sources of distal ejecta are Aristarchus, Harpalus, and Sharp B craters. Returned samples from local and distant materials delivered by impact will thus provide significant new insights into lunar geochronology, inner Solar System impact fluxes, the age of very young mare basalts, the role of the PKT in the generation of mare basalts, the role of sinuous rilles in lava flow emplacement, and the thermal evolution of the Moon. (C) 2020 Elsevier B.V. All rights reserved.