CAJ | 학술논문

同位素地质年代学是月球形成与演化研究的重要工具.目前对月岩和月球陨石的研究积累了大量的同位素年代学资料,其测试的主要方法包括K-Ar、Ar-Ar、Rb-Sr、Sm-Nd、Lu-Hf、Re-Os、Pb-Pb和U-Pb等.根据目前获得的资料,本文对月球上不同类型岩石的形成年龄进行了总结,发现月球高地岩石主要形成于45～38亿年,而月海玄武岩相对年轻,大致形成于38～31亿年.根据这一年代资料,结合对月岩样品进行的短半衰期Hf-W与Sm-Nd同位素体系的研究结果,认为月球大致形成于45亿年,其后开始由岩浆海导致的内部核-幔-壳的分异,岩浆结晶的低密度斜长岩构成最初的月壳,而密度大的岩石构成月幔,而此月幔则成为后来月海玄武岩的主要岩浆源区.同时指出了当前月岩同位素地质年代学存在的问题,并根据技术进展的情况,对未来月岩同位素年代学的发展趋势作了全面的分析.
동위소지질년대학시월구형성여연화연구적중요공구.목전대월암화월구운석적연구적루료대량적동위소년대학자료,기측시적주요방법포괄K-Ar、Ar-Ar、Rb-Sr、Sm-Nd、Lu-Hf、Re-Os、Pb-Pb화U-Pb등.근거목전획득적자료,본문대월구상불동류형암석적형성년령진행료총결,발현월구고지암석주요형성우45～38억년,이월해현무암상대년경,대치형성우38～31억년.근거저일년대자료,결합대월암양품진행적단반쇠기Hf-W여Sm-Nd동위소체계적연구결과,인위월구대치형성우45억년,기후개시유암장해도치적내부핵-만-각적분이,암장결정적저밀도사장암구성최초적월각,이밀도대적암석구성월만,이차월만칙성위후래월해현무암적주요암장원구.동시지출료당전월암동위소지질년대학존재적문제,병근거기술진전적정황,대미래월암동위소년대학적발전추세작료전면적분석.
Isotopic geochronology is one of the important tools to study formation and evolution of the Moon.The available dating techniques applied to the lunar rocks and meteorites include K-Ar,Ar-Ar,Rb-Sr,Sm-Nd,Lu-Hf,Re-Os,Pb-Pb and U-Pb,etc.According to the data obtained by these methods,the highland rocks were mostly formed during 4.5-3.8 Ga;whereas the mare basalts,mainly erupted in the period of 3.8-3.1 Ga,are a little younger than that of the highland rocks.This conclusion,combined with the data obtained fmm the short-lived Hf-W and Sm-Nd isotopic systematics,suggests that the Moon was initially accreted at 4.5 Ga,followed by development of the global lunar magma ocean(LMO).The primary lunar crust is composed by ferroan anorthosite which was produced by flotation of plagioclase during crystallization of the LMO.However,the mafic minerals,coevally crystallized with the plagioclase,sank to the base of the LMO due to their high density,and made up the main part of the lunar mantle,which served as the source during later mare basaltic magmatism.In addition,a comprehensive overview is given to the geochronologic study of the lunar rocks to date,and propose some key technical points which should be developed in the future.