Barboni Mélanie, Szymanowski Dawid, Schoene Blair, Dauphas Nicolas, Zhang Zhe J, Chen Xi, McKeegan Kevin D
School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85281, USA.
Institute of Geochemistry and Petrology, ETH Zurich, 8092 Zurich, Switzerland.
Sci Adv. 2024 Jul 26;10(30):eadn9871. doi: 10.1126/sciadv.adn9871. Epub 2024 Jul 24.
The Moon has had a complex history, with evidence of its primary crust formation obscured by later impacts. Existing U-Pb dates of >500 zircons from several locations on the lunar nearside reveal a pronounced age peak at 4.33 billion years (Ga), suggesting a major, potentially global magmatic event. However, the precision of existing geochronology is insufficient to determine whether this peak represents a brief event or a more protracted period of magmatism occurring over tens of millions of years. To improve the temporal resolution, we have analyzed Apollo 14, 15, and 17 zircons that were previously dated by ion microprobe at ~4.33 Ga using isotope dilution thermal ionization mass spectrometry. Concordant dates with sub-million-year uncertainty span ~4 million years from 4.338 to 4.334 Ga. Combined with Hf isotopic ratios and trace element concentrations, the data suggest zircon formation in a large impact melt sheet, possibly linked to the South Pole-Aitken basin.
月球有着复杂的历史，其原始地壳形成的证据被后来的撞击所掩盖。从月球近侧几个地点获取的500多个锆石的现有铀铅年代测定结果显示，在43.3亿年前（Ga）有一个明显的年龄峰值，这表明发生了一次重大的、可能是全球性的岩浆活动。然而，现有地质年代学的精度不足以确定这个峰值代表的是一个短暂事件还是持续数千万年的更长时间的岩浆活动期。为了提高时间分辨率，我们分析了阿波罗14号、15号和17号任务采集的锆石，这些锆石之前用离子微探针测定的年代约为43.3亿年，此次我们使用同位素稀释热电离质谱法进行分析。不确定度在百万年以下的一致年代范围从43.38亿年到43.34亿年，跨度约400万年。结合铪同位素比值和微量元素浓度，数据表明锆石形成于一个大型撞击熔体层中，可能与南极-艾特肯盆地有关。
