Despite being essentially water-free, nominally anhydrous minerals such as plagioclase and pyroxene represent the biggest reservoir of water in most lunar rocks due to their sheer abundance. Apatite, which incorporates F, Cl, and OH into its mineral structure as essential crystal components, on the other hand, is the only other volatile-bearing phase common in lunar samples. Here, we present the first coordinated study of volatiles (e.g., H2O, Cl, F, and S) in nominally anhydrous minerals combined with isotopic measurements in apatite from the ancient lunar basalt fragments from meteorite Miller Range (MIL) 13317. Apatite in MIL 13317 basalt contains ∼ 2000 ppm H2O and has an elevated δD values (+ 523–737 ‰), similar to Apollo mare basalts, but has high δ37Cl values (+ 29–36 ‰), similar to apatite found in several KREEP-rich samples. MIL 13317 is unique compared with other lunar basalts; it has both elevated δD and δ37Cl values currently only observed in highlands sample 79215 (a granulitic impactite). Based on measurements of H2O in nominally anhydrous minerals and in apatite, the source magma of MIL 13317 basalt is estimated to contain ∼ 130–330 ppm H2O. Assuming reasonable levels of partial melting of the lunar mantle and magmatic degassing during eruption of the basalt, the Moon contained at least one reservoir with < 100 ppm H2O, a δD value of < 0 ‰ similar to carbonaceous chondrites, and extensively fractionated Cl isotopes prior to 4.332 Gyr, the crystallization age of the MIL 13317 basalt.

中文翻译：

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对古代月球玄武岩中磷灰石和硅酸盐矿物中的挥发物进行协调微量分析


尽管基本上不含水，但名义上的无水矿物，如斜长石和辉石，由于其绝对丰富性，代表了大多数月球岩石中最大的水库。另一方面，磷灰石将 F、Cl 和 OH 作为重要的晶体成分掺入其矿物结构中，是月球样品中唯一常见的其他含挥发物的相。在这里，我们提出了对名义上无水矿物中挥发物（例如 H2O、Cl、F 和 S）的首次协调研究，并结合了陨石米勒山脉 （MIL） 13317 的古代月球玄武岩碎片中磷灰石的同位素测量。MIL 13317 玄武岩中的磷灰石含有 ∼ 2000 ppm 的 H2O，δD 值升高 （+ 523–737 ‰），类似于阿波罗母马玄武岩，但具有较高的 δ37Cl 值 （+ 29–36 ‰），类似于在几个富含 KREEP 的样品中发现的磷灰石。MIL 13317 与其他月球玄武岩相比是独一无二的;它的 δD 和 δ37Cl 值均升高，目前仅在高地样品 79215（一种颗粒状撞击石）中观察到。根据对名义上无水矿物和磷灰石中 H2O 的测量，MIL 13317 玄武岩的源岩浆估计含有约 130-330 ppm 的 H2O。假设月球地幔部分熔化和玄武岩喷发期间岩浆脱气的合理水平，月球至少包含一个储层，其 < 100 ppm H2O，δD 值为 < 0 ‰，类似于碳质球粒陨石，并且在 MIL 13317 玄武岩的结晶年龄 4.332 Gyr 之前广泛分馏的 Cl 同位素。