嫦娥五号角砾岩岩屑中矿物及玻璃的地球化学特征  

Geochemical characteristics of minerals and glass in Chang'e-5 breccia fragments

作　　者：王莎莎 李林曦 惠鹤九 万博[1] WANG ShaSha;LI LinXi;HUI HeJiu;and WAN Bo(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;School of the Earth Sciences and Engineering,Nanjing University,Nanjing 210023,China)

机构地区：[1]中国科学院地质与地球物理研究所,北京100029 [2]中国科学院大学地球与行星科学学院,北京100049 [3]南京大学地球科学与工程学院,南京210023

出　　处：《岩石学报》2025年第4期1135-1148,共14页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(42325206)资助。

摘　　要：嫦娥五号(CE-5)任务返回了位于风暴洋克里普地体(PKT)中年轻的玄武岩单元的月壤样品,为了解月球的演化历史提供了新的视角。已有的大量研究集中在月壤中的玄武岩岩屑,但同样拥有着可观数量的角砾岩岩屑却较少被研究。角砾岩为了解月壳成分、岩性多样性、撞击过程和地质演化提供了重要的信息,也是月球研究中重要的研究对象。本项研究的样品为铲取月壤样品中的角砾岩岩屑,其主要表现为撞击熔融碎屑、岩石和矿物碎屑嵌套在细粒基质中,可含少量玻璃碎屑。系统的岩石矿物学研究发现,CE-5角砾岩岩屑中的矿物以橄榄石、辉石、长石为主,伴有不同程度的破裂;多见撞击玻璃,未见高压相撞击特征矿物。本研究中的角砾岩岩屑均遭受过S3及以上等级的撞击,撞击压力>~20GPa。少部分具有流动结构的长石质玻璃的角砾岩岩屑所遭受的冲击的等级则可达到S5,甚至更高(撞击压力>~42GPa,熔融温度>~1100℃)。角砾岩岩屑中矿物的化学组成表明,构成CE-5角砾岩的主要物质是CE-5着陆区本地的年轻玄武岩,但有约1%~8.5%的矿物和CE-5玄武岩有差异,可能是来自着陆区月海之外的成分。玻璃的化学成分可以通过简单的玄武质矿物混熔来解释,仅个别岩屑中的玻璃记录了月球高地物质的化学组成。对比Apollo及Luna的样品外来成分及年龄,可初步推测CE-5着陆区在~2.0Ga的玄武质岩浆喷发后并未经历大的表面改造,这和月表撞击通量的减少一致。The Chang'e-5(CE-5)mission returned lunar soil from the young basalt unit in the Procellarum KREEP Terrane(PKT),providing new insights into the Moon s evolutionary history.Literature studies have focused on basalt fragments in lunar soil and few attentions has been dedicated on breccia fragments.Breccia provides valuable information on the composition of the lunar crust,rock diversity,impact processes,and geological evolution,making it an important subject in lunar studies.The samples analyzed in this study are breccia fragments,primarily composed of impact-melt fragments,rock and mineral fragments embedded in a fine-grained matrix,and small amounts of glass fragments.Systematic petrological and mineralogical analyses reveal that the primary minerals in the CE-5 breccia fragments are olivine,pyroxene,and feldspar,exhibiting varying degrees of fracturing.Common impact-melted glass is present,though high-pressure phases are absent.The breccia fragments in this study show evidence of impacts at S3 grade or higher,corresponding to pressures greater than~20GPa.Some breccia fragments,containing feldspathic glass with flow-like structures,have undergone impacts at S5 grade or higher,with pressures exceeding~42GPa and melting temperatures above~1100℃.The mineral chemical compositions in the breccia fragments suggest that the primary material of the CE-5 breccia is young basalt from the CE-5 landing site,and that ca.1%~8.5%of the minerals may represent exogenous,non-CE-5 mare basalt components.The glass composition aligns with simple basaltic mineral melting,though a few glass fragments capture the chemical signatures of lunar highlands materials.Comparisons with exogenous components and ages from Apollo and Luna samples suggest that the CE-5 landing site experienced minimal surface alteration after the basaltic magma eruption at~2.0Ga,consistent with the reduced lunar impact flux.

关 键 词：月球 嫦娥五号 月球角砾岩 太空风化 撞击作用 

分 类 号：P575[天文地球—矿物学] P691[天文地球—地质学]