为确定延边地区明月沟组火山岩的形成时代、成因及构造背景，对明月沟组中的安山岩开展了岩石学、SIMS 锆石 U- - Pb 年代学、岩石地球化学及锆石 Hf 同位素特征研究。结果表明: 明月沟组安山岩中的锆石为岩浆成因锆石。代表安山岩形成时代的两件样品中锆石的 206 Pb/ 238 U 加权平均年龄分别为 (111 ±4) Ma (n =6 ，MSWD =3. 2) 和 (113 ±3) Ma (n =6 ，MSWD = 1. 4)，属早白垩世晚期。岩石地球化学特征上，明月沟组安山岩相对富钠，属高钾钙碱性系列，具有明显富集大离子亲石元素 (K、Ba) 和轻稀土元素，亏损重稀土元素和 Ta、Nb 等高场强元素的特征，结合其 Hf 同位素组成特征，暗示明月沟组安山岩的源岩应为受俯冲板片流体成份参与的亏损地幔。结合区域构造演化背景，明月沟组安山岩的形成应与早白垩世古太平洋板块向欧亚大陆板块的斜向俯冲作用相关。

In order to determine the geochronology，petrogenesis and tectonic background of Mingyuegou For- mation volcanic rocks in Yanbian area，the research of petrology，SIMS zircon U- -Pb geochronology，geochemistry and zircon Hf isotopic have been taken． The results show that the zircons from the andesite rocks are magma genesis zircons，and the zircon 206 Pb/ 238 U dating were (111 ±4) Ma (n =6，MSWD =3. 2) and (113 ±3) Ma (n =6， MSWD =1. 4)，belonging to the later Early Cretaceous． The geochemical data show that the andesite rocks belong to high- k calc- alkaline series，enriched in LILE (K，Ba) and LREE，relatively depleted in HREE and HFSE (such as Ta，Nb)． Combined with Hf isotopes，it is showed the primary magmas of the andesite rocks of the Mingyuegou Formation were from the depleted mantle affected by subducted slab fluids． Combined with the research of regional tectonics，the formation of andesite rocks may be closely related to the subduction of Paleo - - Pacific plate towards Eursia a plate．