辽东半岛～2.2Ga岩浆事件及其地质意义

发布时间：2018-07-23 20:46

【摘要】：本文报道了辽东半岛古元古代胶—辽—吉活动带内辽河群变质火山岩和辽吉花岗岩的锆石LA-ICP-MS U-Pb年代学和地球化学数据。变质安山岩的锆石具典型的岩浆振荡环带结构和较高的Th/U值(0.5),锆石U-Pb年龄为(2 182±6)Ma和(2 229±22)Ma,该年龄可代表安山岩的形成年龄。辽吉花岗岩的锆石同样具有典型的岩浆振荡环带结构和较高的Th/U值(0.3),锆石U-Pb年龄为(2 199±10)Ma,代表花岗岩的侵位时代,在误差范围内与辽河群火山岩喷发时代一致,表明辽吉花岗岩并不是辽河群的基底,二者可能为同一次岩浆作用过程的产物。辽东半岛~2.2Ga岩浆事件的识别及性质,对于正确认识古元古代胶—辽—吉活动带的属性至关重要。结合前人有关辽东半岛前寒武纪岩石的研究成果,本文研究认为胶—辽—吉活动带的形成演化可能与弧-陆碰撞有关。
[Abstract]:Zircon LA-ICP-MS U-Pb chronology and geochemistry data of metamorphic volcanic rocks and Liaoji granites of Liaohe Group in the Gu Yuan activity zone of Liaodong Peninsula are reported in this paper. The zircon of the metamorphic andesite has a typical magmatic oscillating zonal structure and a high Th/U value (0. 5). The zircon U-Pb age is (2 182 卤6) Ma and (2 229 卤22) Ma, which may represent the age of formation of the andesite. The zircon of Liaoji granite also has typical magmatic oscillating ring structure and high Th/U value (0. 3). The zircon U-Pb age is (2 199 卤10) Ma, which represents the emplacement age of the granite and is consistent with the eruption age of volcanic rocks in the Liaohe Group within the error range. It is suggested that the Liaoji granite is not the basement of the Liaohe Group, and they may be the product of the same magmatic process. The identification and nature of the 2.2 Ga magma event in Liaodong Peninsula is very important for the correct understanding of the attributes of the ancient Jiao-Liaojia-Ji active belt in Gu Yuan. Based on previous studies on Precambrian rocks in the Liaodong Peninsula, it is considered that the formation and evolution of the Jiao-Liaojia-Ji active zone may be related to the arc-land collision.
【作者单位】：合肥工业大学资源与环境工程学院;北京大学地球与空间科学学院/造山带与地壳演化教育部重点实验室;
【基金】：科技部“973”项目(2012CB416603) 国家自然科学基金重点项目(90914001) 北京大学开放测试基金(0000010541) 吉林大学大学生创新性实验计划项目(2010C61164)~~
【分类号】：P588.1

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