CAJ | 학술논문

在野外地质调查的基础上，对辽西建平杂岩中斜长角闪岩和基性麻粒岩进行了LA-ICP-MS锆石U-Pb同位素年代学和地球化学研究。结果显示，研究区新太古代末—古元古代初的变质年龄主要集中在2465～2453 Ma，结晶年龄为～2593 Ma。变基性岩原岩多属于拉斑玄武岩系列。两类岩石具有较高的Al2 O3含量（平均值14.49％）和较高的TiO2含量（平均值1.15％），与大洋玄武岩特征相似。样品Mg＃变化较大（35～63），可能与岩浆上升过程中遭受地幔物质不同程度的混染有关。Ce／Yb-Ce图解反映了本区岩石样品起源于石榴子石二辉橄榄岩地幔。部分样品的轻、重稀土元素分馏程度相对较强（（La／Yb）N ＝5.67～10.87），同时具明显的Nb、Ta、Ti负异常，与岛弧玄武岩的特征类似。平坦型稀土配分曲线显示正常型洋中脊玄武岩的特征。综合分析认为，本区新太古代末期基性岩浆作用形成于活动大陆边缘弧的构造背景下，并在稍晚的碰撞过程中发生变质作用，进而推断出新太古代末期研究区存在与现代板块类似的构造体制。
재야외지질조사적기출상，대료서건평잡암중사장각섬암화기성마립암진행료LA-ICP-MS고석U-Pb동위소년대학화지구화학연구。결과현시，연구구신태고대말—고원고대초적변질년령주요집중재2465～2453 Ma，결정년령위～2593 Ma。변기성암원암다속우랍반현무암계렬。량류암석구유교고적Al2 O3함량（평균치14.49％）화교고적TiO2함량（평균치1.15％），여대양현무암특정상사。양품Mg＃변화교대（35～63），가능여암장상승과정중조수지만물질불동정도적혼염유관。Ce／Yb-Ce도해반영료본구암석양품기원우석류자석이휘감람암지만。부분양품적경、중희토원소분류정도상대교강（（La／Yb）N ＝5.67～10.87），동시구명현적Nb、Ta、Ti부이상，여도호현무암적특정유사。평탄형희토배분곡선현시정상형양중척현무암적특정。종합분석인위，본구신태고대말기기성암장작용형성우활동대륙변연호적구조배경하，병재초만적팽당과정중발생변질작용，진이추단출신태고대말기연구구존재여현대판괴유사적구조체제。
Based on the field work,LA-ICP-MS ziron U-Pb geochronology and geochemistry of the amphibolite and granulite from Jianping metamorphic complex in Western Liaoning Province,this study suggests that the metamorphic event of late Neoarchean and early Paleoproterozoic are mainly focused in 2 465 -2 453 Ma and the age of crystallization is ~2 593 Ma.The two types of samples have relatively high Al2 O3 (average is 14.49%)and high TiO2 (average is 1.15%),which are similar to the rocks originated from ocean basalt.Mg#values of samples have a larger variation (35 -63 )which indicate that magma maybe contaminated by mantle substances during their ascent.Ce/Yb-Ce diagram reflect that samples stem from garnet lherzolite mantle.Am-phibolite and most granulites are characterized by enriched LREE ((La/Yb)N =5.67 -10.87),and obvious depletion of Nb,Ta,Ti,which is similar to that of island arc basalt,while flat curve has a character of N-type MORB.Comprehensive analysis shows that the mafic magmatism is formed in an active continental margin tec-tonic setting in the late Neoarchean,and then metamorphosed during the process of collision.So it is suggested that the study area exists a tectonic regime similar to modern plate in late Neoarchean.