Abstract The Moon and Earth share similar relative abundances and isotope compositions of refractory lithophile elements, indicating that the Moon formed from a silicate reservoir that is chemically indistinguishable from the Earth's primitive silicate mantle. In contrast, most volatile elements are depleted in lunar mare basalts compared to Earth's mantle and differ in their isotope composition. However, the depletion of volatile elements is not a simple function of their condensation temperature, indicating multiple mechanisms that established the lunar volatile element budget. Specifically, the chalcophile elements S, Se and Te are not depleted in lunar basalts compared to their terrestrial counterparts. In this study, the abundances and stable isotope compositions of the volatile and chalcophile element Se measured in three lunar mare basalts and seven soils are used to refine the processes that caused volatile element depletion on the Moon. The Se isotope composition of two lunar mare basalts ( δ 82 / 78 Se = 1.08 and 0.8‰) is significantly heavier compared to chondrites (−0.20 ± 0.26‰; 2 s.d.) and terrestrial basalts (0.29 ± 0.24‰; 2 s.d.). The offset in the Se isotope composition is attributed to a volatility controlled loss of Se from the Moon. The lack of chalcophile element depletion in lunar mare basalts is then explained by sulphide segregation in the Earth's mantle after the Moon forming impact followed by a late veneer of chondritic material to the Earth. Seven lunar soils were found to have chondritic S/Se ratios, but have δ 82 / 78 Se values that are 6 to 13‰ heavier compared to mare basalts. This fractionation is likely the result of coupled and repeating processes of meteoritic material addition and concomitant partial evaporation. Results from numerical modelling indicate that isotope fractionation in lunar soils is due to partial evaporation of FeSe and FeS with evaporative loss of about 20% for both Se and S.

中文翻译：

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月球岩石的硒同位素组成：对月球形成及其挥发损失的影响

摘要 月球和地球具有相似的难熔亲石元素的相对丰度和同位素组成，表明月球是由硅酸盐储层形成的，在化学上与地球的原始硅酸盐地幔无法区分。相比之下，与地球的地幔相比，月球玄武岩中的大多数挥发性元素都被耗尽，并且它们的同位素组成不同。然而，挥发性元素的消耗并不是它们冷凝温度的简单函数，这表明建立月球挥发性元素预算的多种机制。具体而言，与地球上的对应物相比，月球玄武岩中的亲硫元素 S、Se 和 Te 并未耗尽。在这项研究中，在三块月球玄武岩和七块土壤中测量的挥发性和亲硫元素硒的丰度和稳定同位素组成被用来改进导致月球上挥发性元素消耗的过程。与球粒陨石 (-0.20 ± 0.26‰; 2 sd) 和陆地玄武岩 (0.29 ± 0.24‰) 相比，两块月海玄武岩 ( δ 82 / 78 Se = 1.08 和 0.8‰) 的 Se 同位素组成明显更重。2 Se 同位素组成的偏移归因于来自月球的 Se 的挥发性控制损失。月球玄武岩中没有亲硫元素耗尽的原因是月球形成撞击后地球地幔中的硫化物分离，随后是球粒陨石材料的后期饰面到地球。发现七个月球土壤具有球粒状 S/Se 比率，但 δ 82 / 78 Se 值比母玄武岩重 6 到 13‰。这种分馏很可能是陨石物质添加和伴随的部分蒸发的耦合和重复过程的结果。数值模拟结果表明，月球土壤中的同位素分馏是由于 FeSe 和 FeS 的部分蒸发，Se 和 S 的蒸发损失约为 20%。