【摘要】 U-Pb锆石测年结果表明,东宁地区太平岭岩体形成于201 Ma,与区域上七十二顶子、闹枝沟及珲春大荒沟等岩体形成时代一致,均为晚三叠世末。岩石类型以花岗闪长岩和二长花岗岩为主,地球化学特征表明该期花岗岩属于中钾钙碱性系列,并有向高钾钙碱性系列演化的趋势;富集大离子亲石元素Rb、Th、K、La,相对亏损Sr、P、Ti和高场强元素Nb、Ta、Zr、Hf等,Ba相对Rb、Th具有轻微的负异常。同位素地球化学研究表明,本区花岗岩具有低ISr、高εNd(t)、年轻Nd模式年龄的特点。综合研究表明,该期花岗岩的形成与大洋板块的俯冲作用有关,标志着古太平洋板块对东北地区俯冲作用的开始。更多还原

【Abstract】 Precise zircon U-Pb dating of the Taipingling pluton in Dongning area,Heilongjiang Province shows that the pluton was formed in the Late Triassic period,similar to those plutons at the Qishierdingzi,Naozhigou and Dahuanggou in Hunchun area.The Late Triassic granitoids in Yanbian-Dongning area are mainly composed of granodiorite and monzogranite.Their geochemical characteristics show they belong to medium K calc-alkaline series,and have a tendency of evolving into high-K calc-alkaline series.They are enriched in LILE(Rb,Th,K,La,et al.),depleted in Sr,P,Ti and the HFSE(Nb,Ta,Zr,Hf,et al.).Ba shows a slight depletion compared with Rb and Th.The granitoids also show low Isr,high εNd(t) and young TDM.Through studies on petrology,mineral assemblages and geochemistry,the formation of the granitoids is suggested to be related to the subduction of the oceanic crust,being an indication of the beginning of paleo-Pacific Oceanic plate subduction underneath the NE China.更多还原