胶北旌旗山地区禄格庄岩组长石石英岩碎屑锆石U⁃Pb测年及其地质意义  

Detrital Zircon U⁃Pb Dating of Arkose⁃Quartzite in the Lugezhuang Formation in the Jingqishan Area,Jiaobei Terrane,and Its Geological Significance

作　　者：张宇佳 刘平华[2] 周万蓬[1] 王义龙 王宏宇 Zhang Yujia;Liu Pinghua;Zhou Wanpeng;Wang Yilong;Wang Hongyu(State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang 3300013,China;Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China;Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing 100081,China)

机构地区：[1]东华理工大学核资源与环境国家重点实验室,江西南昌330013 [2]中国地质科学院地质研究所,北京100037 [3]中国地质科学院地质力学研究所,北京100081

出　　处：《地球科学》2022年第9期3431-3446,共16页Earth Science

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

摘　　要：荆山岩群是胶北地体最重要的古元古代变沉积岩系之一,经历了高角闪岩相‒麻粒岩相变质与韧性变形,准确限定其沉积时代与物质来源对探究胶‒辽‒吉带古元古代构造演化过程具有重要意义.本文利用LA-ICP-MS(激光剥蚀电感耦合等离子质谱仪)对旌旗山地区荆山岩群禄格庄岩组中长石石英岩进行了锆石U-Pb测年和稀土元素分析.根据碎屑锆石内部结构和年龄结果,认为在最年轻一组碎屑锆石中谐和的^(207)Pb/^(206)Pb加权平均年龄2120 Ma,可以大致限定其原岩的最大沉积时代,两件样品获得的变质年龄分别为1886±12 Ma与1969±23 Ma,结合区内禄格庄岩组被2103~2085 Ma二长花岗质片麻岩侵入的地质关系,初步限定旌旗山地区禄格庄岩组的沉积时代约为2100 Ma.长石石英岩中有效碎屑锆石年龄谱图呈现2105 Ma主峰值年龄和2185 Ma次峰值年龄,指示旌旗山地区禄格庄岩组的主要物源为古元古代(2200~2100 Ma)中‒酸性岩浆岩或再循环的产物,同时接受了少量太古宙的碎屑物质.综合胶‒辽‒吉带已发表的其他相关数据,认为以荆山岩群禄格庄岩组为代表的胶‒辽‒吉带南侧底部变沉积岩沉积时可能位于弧后盆地靠近岛弧一侧,以粉子山岩群小宋岩组为代表的胶‒辽‒吉带北侧底部变沉积岩则可能位于弧后盆地靠近太古宙大陆一侧.The Jingshan Group,which has undergone high amphibolite to granulite facies metamorphism and ductile deformation,is one of the most widely distributed Paleoproterozoic meta-sedimentary rocks in the Jiaobei terrane of the Jiao-Liao-Ji Belt.Depositional timing and provenance of the Jingshan Group are vital for understanding the Paleoproterozoic tectonic evolution of the Jiao-Liao-Ji Belt.In this study,LA-ICP-MS(laser ablation inductively coupled plasma mass spectrometry)was used to analyze the zircon U-Pb ages and rare earth element compositions of arkose-quartzites in the Lugezhuang Formation of the Jingshan Group.Based on the internal structure of zircons and U-Pb ages,the concordant^(207)Pb/^(206)Pb age of 2120 Ma in the youngest group of detrital zircons is chosen as the maximal depositional timing of the Lugezhuang Formation.Two metamorphic ages in the two samples are 1886±12 Ma and 1969±23 Ma,respectively.Combined with the above data and the geological relationship which the Lugezhuang Formation was intruded by the 2103-2085 Ma granitic gneisses in the Jingqishan area,it is speculated that the depositional timing of the Lugezhuang Formation is circa 2100 Ma.Detrital zircon age patterns from samples are characterized by the major peak of 2105 Ma and secondary peak of 2185 Ma.The new detrital age data reveals that the Lugezhuang Formation in Jingqishan area is mainly derived from Paleoproterozoic intermediate-acidic magmatic rocks or recycled products of the Paleoproterozoic(2200-2100 Ma)rocks with a small amount of Archaean detrital material.Combined with other published data of the Jiao-Liao-Ji Belt,it is speculated that the bottom meta-sedimentary rocks in the southern part of the Jiao-Liao-Ji Belt,which is represented by the Lugezhuang Formation of the Jingshan Group,may be deposited on the side of the continental arc of the backarc basin,and the bottom metasedimentary rocks in the northern part of the Belt,which is represented by the Xiaosong Formation of the Fenzishan Group,may be close to the side of t

关 键 词：荆山岩群 禄格庄岩组 长石石英岩 锆石U‐Pb定年 岩石学 

分 类 号：P597.3[天文地球—地球化学]