华北克拉通胶北地体蓬莱群辅子夼组碎屑锆石U-Pb定年及其地质意义  

Detrital Zircon U⁃Pb Dating of the Fuzikuang Formation,Penglai Group in Jiaobei Terrane,North China Craton and Its Geological Significance

作　　者：王宏宇 王义龙 刘平华[3] 周万蓬[2] 张宇佳 张传恒[1] Wang Hongyu;Wang Yilong;Liu Pinghua;Zhou Wanpeng;Zhang Yujia;Zhang Chuanheng(School of Earth Sciences and Resources,China University of Geosciences,Beijing 100083,China;School of Earth Sciences,East China University of Technology,Nanchang 330013,China;Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China)

机构地区：[1]中国地质大学地球科学与资源学院,北京100083 [2]东华理工大学地球科学学院,江西南昌330013 [3]中国地质科学院地质研究所,北京100037

出　　处：《地球科学》2021年第9期3074-3090,共17页Earth Science

基　　金：国家自然科学基金项目(Nos.41672191,41972205);中国地质调查局地质大调查二级项目(Nos.DD20190003,DD20190370).

摘　　要：蓬莱群是胶北地区最主要的晚前寒武纪沉积盖层,对研究华北克拉通东南缘晚前寒武纪演化有重要意义.为确认蓬莱群沉积时代与物源特征,本次研究选取栖霞地区蓬莱群辅子夼组中上部的长石石英岩为研究对象,对锆石CL图像、U-Pb年龄以及稀土元素组成开展研究,发现碎屑锆石主要为岩浆锆石,年龄峰值主要集中在1100、1200 Ma以及1600 Ma,缺乏年龄大于1.8 Ga的锆石;其中,最年轻碎屑锆石年龄为1094±39 Ma,结合前人资料,蓬莱群辅子夼组沉积时代被限定在新元古代初期;不同地区的蓬莱群在辅子夼组中部以上物源区是统一的,在辅子夼组下部沉积时期物源发生变化.在区域上,蓬莱群物源特点与朝鲜祥原超群、以及我国辽东细河群、鲁南土门群、徐淮地区淮南群、豫西地区栾川群等华北东缘、南缘新元古代沉积盆地物源相似,物源主要来自华北克拉通以外的古陆.结合古地磁、中‒新元古代岩墙分布等资料,推测发育格林威尔期造山带的克拉通如Laurentia-Siberia-Baltica或Sao Fransico-Congo克拉通与华北克拉通南缘拼合,提供物源.The Penglai Group is an important late Precambrian sedimentary cover in Jiaobei area,which is of great significance to study the late Precambrian evolution in the southeastern margin of the North China Craton.In order to confirm the sedimentary age and provenance characteristics of the Penglai Group in the Jiaobei area,a fine-grained feldspar quartzite in the upper part of the Fuzikuang Formation,Penglai Group in the Qixia area is selected for analyses of the zircon CL image,U-Pb age and REE composition in this study.Results show that detrital zircons mainly belong to magmatic origin,with the peak ages of 1100 Ma,1200 Ma and 1600 Ma,and there are a few zircons with age older than 1.8 Ga.The youngest zircon age is 1094±39 Ma,combined with the previous data,the sedimentary age of the Fuzikuang Formation in the Penglai Group should be limited to early Neoproterozoic.The provenance of the Penglai Group in different areas are the same in the middle and upper parts of the Fuzikuang Formation,but the provenance may change in the lower part of the Fuzikuang Formation.From regional perspective,the provenance characteristics of the Penglai Group are similar to those of the Neoproterozoic strata in the southern margin of the North China Craton,such as the Sangwon System in North Korea,and the Xihe Group in the Liaodong Peninsula,the Tumen Group in the Luxi area,the Huainan Group in Xuhuai area and the Luanchuan Group in western Henan,China.The main provenance areas are outside the North China Craton.Combined with paleomagnetic data and distribution of Meso-Neoproterozoic mafic dykes,we speculate that the southern margin of the North China Craton combined with the craton having Grenvillian orogen on it,maybe Laurentia-Siberia-Baltica Craton or Sao Franco-Congo Craton,which provided the provenance for the Penglai Group.

关 键 词：蓬莱群 辅子夼组 锆石U⁃Pb定年 物源分析 岩石学 

分 类 号：P581[天文地球—岩石学]