Jones Matt J, Evans Alexander J, Johnson Brandon C, Weller Matthew B, Andrews-Hanna Jeffrey C, Tikoo Sonia M, Keane James T
Department of Earth, Environmental and Planetary Sciences, Brown University, Box 1846, 324 Brook Street, Providence, RI 02912, USA.
Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, IN 47907, USA.
Sci Adv. 2022 Apr 8;8(14):eabm8475. doi: 10.1126/sciadv.abm8475.
The formation of the largest and most ancient lunar impact basin, South Pole-Aitken (SPA), was a defining event in the Moon's evolution. Using numerical simulations, we show that widespread mantle heating from the SPA impact can catalyze the formation of the long-lived nearside-farside lunar asymmetry in incompatible elements and surface volcanic deposits, which has remained unexplained since its discovery in the Apollo era. The impact-induced heat drives hemisphere-scale mantle convection, which would sequester Th- and Ti-rich lunar magma ocean cumulates in the nearside hemisphere within a few hundred million years if they remain immediately beneath the lunar crust at the time of the SPA impact. A warm initial upper mantle facilitates generation of a pronounced compositional asymmetry consistent with the observed lunar asymmetry.
最大且最古老的月球撞击盆地——南极-艾特肯盆地（SPA）的形成，是月球演化过程中的一个决定性事件。通过数值模拟，我们表明，SPA撞击引发的广泛地幔加热能够催化不相容元素和地表火山沉积物中长久存在的近侧-远侧月球不对称性的形成，自阿波罗时代发现这一现象以来，其成因一直未得到解释。撞击产生的热量驱动半球规模的地幔对流，如果在SPA撞击发生时，富含钍和钛的月球岩浆海洋堆积物紧邻月球地壳之下，那么在几亿年内，这些堆积物将被隔离在近侧半球。温暖的初始上地幔有利于产生与观测到的月球不对称性相一致的显著成分不对称性。
