CAJ | 학술논문

通过野外观测、锆石LA-ICP-MS U-Pb同位素测定及岩石地球化学等手段，详细地对延边地区明南洞岩体进行了研究。研究表明，延边地区明南洞岩体的成岩年龄为(180.5±0.7) Ma，为早侏罗世岩浆事件的产物。明南洞岩体中SiO2含量为60.71%~67.72%，Al2O3含量为15.60%~17.44%，全碱(Na2O+K2O)值为6.79%~7.63%，K2O/Na2O值为0.61~1.01，A/CNK=0.94~1.01，属高钾钙碱性I型花岗岩，并具有富集轻稀土元素和大离子亲石元素，亏损重稀土元素和高场强元素的特征。以上特征表明，明南洞岩体具有显著的活动大陆边缘及火山弧花岗岩的特点。延边-太平岭地区的陆缘钙碱性、高钾钙碱性花岗岩到张广才岭-小兴安岭地区的双峰式火山岩组合，构成了平行洋壳俯冲方向的成分分带，指示了俯冲的方向，反映了早侏罗世古太平洋板块的俯冲作用。
통과야외관측、고석LA-ICP-MS U-Pb동위소측정급암석지구화학등수단，상세지대연변지구명남동암체진행료연구。연구표명，연변지구명남동암체적성암년령위(180.5±0.7) Ma，위조주라세암장사건적산물。명남동암체중SiO2함량위60.71%~67.72%，Al2O3함량위15.60%~17.44%，전감(Na2O+K2O)치위6.79%~7.63%，K2O/Na2O치위0.61~1.01，A/CNK=0.94~1.01，속고갑개감성I형화강암，병구유부집경희토원소화대리자친석원소，우손중희토원소화고장강원소적특정。이상특정표명，명남동암체구유현저적활동대륙변연급화산호화강암적특점。연변-태평령지구적륙연개감성、고갑개감성화강암도장엄재령-소흥안령지구적쌍봉식화산암조합，구성료평행양각부충방향적성분분대，지시료부충적방향，반영료조주라세고태평양판괴적부충작용。
In this paper Mingnandong pluton was studied throughly by such means as field observation, LA-ICP-MS zircon U-Pb isotopic measurement and petro-geochemistry. The results show that Mingnandong pluton was formed in the Early Jurassic (180.47± 0.71Ma). Chemical analyses yielded the following data for Mingnandong pluton: SiO2=60.71%-67.72%, Al2O3=15.60%-17.44%, Na2O+K2O=6.79%-7.63%, K2O/Na2O=0.61-1.01 and A/CNK=0.94-1.01, implying high-potassium calc-alkaline I-type granites. Besides, Mingnandong pluton is enriched in light rare earth elements and large ion lithophile elements, and depleted in heavy rare earth elements and high field strength elements. These features suggest that Mingnandong pluton has obvious characteristics of active continental margin and volcanic arc granites. The ingredient zonation parallel to the orientation of the subduction of oceanic crust made up of cale-alkaine, high-K calc-alkaline granites and the bimodal volcanic rock association from Yanbian and Taiping Mountain to Xiao Hinggan Mountains and Zhangguangcai Mountain indicate the orientation of the subduction of ancient Pacific plate. In a word, the emplacement of Mingnandong pluton was influenced by the subduction of ancient Pacific plate in the Early Jurassic.