嫦娥五号玄武岩低Ni-Co橄榄石揭秘月球年轻火山成因  

Low Ni and Co olivine in Chang’E-5 basalts reveals the origin of the young volcanism on the Moon

作　　者：苏斌 张迪 陈意 杨蔚 毛骞 李献华 吴福元 Bin Su;Di Zhang;Yi Chen;Wei Yang;Qian Mao;Xian-Hua Li;Fu-Yuan Wu(State Key Laboratory of Lithospheric Evolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;Key Laboratory of Earth and Planetary Physics,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]State Key Laboratory of Lithospheric Evolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China [2]Key Laboratory of Earth and Planetary Physics,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China [3]College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China

出　　处：《Science Bulletin》2023年第17期1918-1927,共10页科学通报（英文版）

基　　金：supported by the National Natural Science Foundation of China(42272057);the Key Research Program of the Chinese Academy of Sciences(ZDBS-SSW-JSC007-15);the Key Research Program of the Institute of Geology and Geophysics,Chinese Academy of Sciences(IGGCAS-202101);the Experimental Technology Innovation Fund of the IGGCAS(11990890)。

摘　　要：对嫦娥五号月球样品研究显示,月球直到20亿年前仍存在岩浆活动.这不仅刷新了人类对月球岩浆活动和热演化历史的认知,也提出了新的科学问题:月球火山活动为什么持续如此之久?本工作对嫦娥五号玄武岩进行橄榄石微量元素研究,发现与阿波罗低钛玄武岩相比,嫦娥五号玄武岩的橄榄石Ni和Co含量较低.结合一系列岩浆结晶模拟,恢复了嫦娥五号和阿波罗玄武岩的初始岩浆Ni和Co含量,揭示嫦娥五号玄武岩的源区含有更多低镁、富铁的岩浆洋晚期堆晶体,它们加入会降低月幔熔点,进而抑制Ni和Co在月幔熔融过程中进入熔体.本研究表明,尽管月球内部在持续缓慢冷却,但岩浆洋晚期堆晶体翻转引起的月幔混合作用可以有效降低月幔源区的熔点,抵消月幔逐渐缓慢变冷的大趋势,引发长期持续的月球火山作用.Mare basalts returned by the Chang’E-5(CE5)mission extend the duration of lunar volcanism almost one billion years longer than previously dated.Recent studies demonstrated that the young volcanism was related neither to radiogenic heating nor to hydrous melting.These findings beg the question of how the young lunar volcanism happened.Here we perform high-precision minor element analyses of olivine in the CE5 basalts,focusing on Ni and Co.Our results reveal that the CE5 basalt olivines have overall lower Ni and Co than those in the Apollo low-Ti basalts.The distinctive olivine chemistry with recently reported bulk-rock chemistry carries evidence for more late-stage clinopyroxene-ilmenite cumulates of the lunar magma ocean(LMO)in the CE5 mantle source.The involvement of these Fe-rich cumulates could lower the mantle melting temperature and produce low MgO magma,inhibiting Ni and Co partitioning into the magma during lunar mantle melting and forming low Ni and Co olivines for the CE5 basalts.Moreover,the CE5 olivines show a continuous decrease of Ni and Co with crystallization proceeding.Fractional crystallization modeling indicates that Co decreasing with crystallization resulted from CaO and TiO_(2)enrichment(with MgO and SiO_(2)depletion)in the CE5 primary magma.This further supports the significant contribution of late-stage LMO cumulates to the CE5 volcanic formation.We suggest that adding easily melted LMO components resulting in mantle melting point depression is a key pathway for driving prolonged lunar volcanism.This study highlights the usefulness of olivine for investigating magmatic processes on the Moon.

关 键 词：火山作用 火山活动 混合作用 橄榄石 岩浆活动 玄武岩 月幔 岩浆洋 

分 类 号：V476.3[航空宇航科学与技术—飞行器设计] P184.5[天文地球—天文学]