Various magmatisms during the subduction-collision process are crucial to reveal the long-term tectonic evolution of the eastern Central Asian Orogenic Belt. In this paper, we present major and trace elements of whole-rock, zircon U-Pb dating and Hf isotope of the Shanmen pluton. Results imply that the Shanmen pluton consists of quartz diorite and mylonitic granite, with zircon U-Pb ages of 263.7–259.6 Ma. The studied quartz diorite contains high Sr/Y (51.19–90.87) and (La/Yb)N (7.82–13.62) ratios, and belongs to adakitic rocks. Coupled with the positive εHf(t) values of +5.71 to +12.8 with no obvious Eu anomaly, we propose that quartz diorite is the product of the interaction between different degrees of slab melt and the overlying mantle wedge. In contrast, the mylonitic granite has lower MgO (0.28 wt% – 0.47 wt%) contents and positive εHf(t) values of +7.79 to +10.15, indicating an affinity with I-type granite originated by partial melting of the intermediate-basic lower crust. The geochemical characteristics and lithological assemblages, along with the Permian magmatic rocks in the Changchun-Kaiyuan area displaying arc rocks affinity, propose their formation is related to the southward subduction of the Paleo-Asian Ocean (PAO). Based on this study and previous evidence, we lean towards adopting a middle-late Permian slab break-off model, wherein the PAO did not close until the late Permian.

俯冲-碰撞过程中的各种岩浆活动对于揭示中亚造山带东部的长期构造演化至关重要。本文介绍了山门岩体的全岩主量元素和微量元素、锆石U-Pb定年和Hf同位素。结果表明，山门岩体由石英闪长岩和糜棱岩花岗岩组成，锆石U-Pb年龄为263.7-259.6 Ma。研究的石英闪长岩含有较高的Sr/Y（51.19-90.87）和（La/Yb）N（7.82-13.62）比率，属于埃达克岩。再加上+5.71至+12.8的正ε Hf (t)值且没有明显的Eu异常，我们推测石英闪长岩是不同程度的板片熔融与上覆地幔楔相互作用的产物。相比之下，糜棱岩花岗岩的 MgO 含量较低（0.28 wt% – 0.47 wt%），正 ε Hf (t) 值为 +7.79 至 +10.15，这表明与 I 型花岗岩的亲和力源于中间体的部分熔融。基本下地壳。地球化学特征和岩性组合，以及长春-开原地区二叠纪岩浆岩表现出的弧岩亲缘性，推测其形成与古亚洲洋（PAO）向南俯冲有关。根据这项研究和之前的证据，我们倾向于采用二叠纪中晚期板片断裂模型，其中 PAO 直到二叠纪晚期才关闭。