漠河盆地中侏罗世绣峰组物源分析及构造意义  

Provenance Analysis and Tectonic Implication of Middle Jurassic Xiufeng Formation in the Mohe Basin

作　　者：周传芳 冯嘉 杨华本 段明新 王久懿 陈卓 杜兵盈 梁中恺 孙彦峰 于俊博 姜平 Zhou Chuanfang;Feng Jia;Yang Huaben;Duan Mingxin;Wang Jiuyi;Chen Zhuo;Du Bingying;Liang Zhongkai;Sun Yanfeng;Yu Junbo;Jiang Ping(Harbin Center for Integrated Natural Resources Survey,China Geological Survey,Harbin 150081,China;Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China;School of Earth Sciences and Resources,China University of Geosciences,Beijing 100083,China;Heilongjiang Institute of Geological Sciences,Harbin 150080,China)

机构地区：[1]中国地质调查局哈尔滨自然资源综合调查中心,哈尔滨150081 [2]中国地质科学院地质研究所,北京100037 [3]中国地质大学(北京)地球科学与资源学院,北京100083 [4]黑龙江省地质科学研究所,哈尔滨150080

出　　处：《吉林大学学报（地球科学版）》2023年第2期450-474,共25页Journal of Jilin University：Earth Science Edition

基　　金：中国地质调查局项目(DD2016007803,DD20191014,DZ20220105)。

摘　　要：漠河盆地位于大兴安岭北部,绣峰组作为漠河盆地最下部层位,其形成时代、物源区特征及大地构造背景等对研究漠河盆地的形成与演化具有重要意义。本文对漠河盆地西南缘绣峰组砂岩进行了碎屑锆石LA-ICP-MS U-Pb年代学和地球化学分析。锆石年代学研究表明,147组碎屑锆石年龄分布于778~181 Ma之间,显示出一个主峰约为198 Ma,分为778、528~393、252、223~181 Ma等4个年龄组,分别与新元古代Rodinia超大陆裂解事件、额尔古纳地块与兴安地块碰撞拼合岩浆活动事件、古亚洲洋俯冲闭合岩浆活动事件和蒙古—鄂霍茨克俯冲闭合岩浆活动事件相对应。砂岩岩石地球化学分析结果显示:w(SiO_(2))为70.59%~73.29%,w(Al_(2)O_(3))为13.91%~14.93%,Al_(2)O_(3)/SiO_(2)值为0.19~0.21,K_(2)O/Na_(2)O值为0.66~1.22,化学蚀变指数(CIA)值为52.58~56.04,平均为53.82,反映绣峰组砂岩形成于低等化学风化程度的古气候环境;稀土元素球粒陨石标准化曲线呈右倾模式,重稀土元素配分曲线平坦,与活动大陆边缘的曲线吻合较好,LREE/HREE值在3.74~5.73之间,(La/Yb)N值为11.27~19.08,δEu值为0.59~0.98,具中等偏弱的负Eu异常;全球平均大陆上地壳(UCC)标准化稀土元素配分曲线较为平缓,(La/Yb)UCC值为1.01~1.72,平均为1.26,(δEu)UCC值为0.84~1.40,平均为1.13,与全球平均大陆上地壳的稀土元素质量分数接近;亏损高场强元素Nb、Ta、Ti、P和大离子亲石元素Ba、Sr,富集高场强元素Th、Hf和大离子亲石元素Rb、K,在原始地幔标准化微量元素蛛网图中,曲线与活动大陆边缘相似。综合研究认为,绣峰组砂岩物源主要为晚三叠世—早侏罗世火成岩,物源区构造环境为与蒙古—鄂霍茨克造山带俯冲闭合有关的活动大陆边缘。Mohe basin is located in the northern part of the Great Xing’an Range.As the lowest layer in the Mohe basin,the formation age,provenance characteristics and tectonic settings of the Xiufeng Formation are of great significance to the study of the formation and evolution of the Mohe basin.The detrital zircon LA-ICP-MS U-Pb geochronology and geochemical analysis of sandstones from the Xiufeng Formation in the southwestern margin of the Mohe basin were carried out.Zircon geochronology studies show that 147 detrital zircon ages are distributed between(778±8)Ma and(181±2)Ma,showing a main peak at 198 Ma,divided into four age groups:778 Ma,528-393 Ma,252 Ma,223-181 Ma,which correspond to the breakup of the Neoproterozoic Rodinia supercontinent,magmatic events related with collision and integration of Erguna block and Xing’an block,the subduction and closure of the Paleo-Asian Ocean,and the magmatism related with subduction and closure,of Mongolia-Okhotsk,respectively.The results of geochemical analysis of sandstones show that w(SiO_(2))is 70.59%-73.29%,w(Al_(2)O_(3))is 13.91%-14.93%,Al_(2)O_(3)/SiO_(2)is 0.19-0.21,K_(2)O/Na_(2)O values in a range of 0.66-1.22,and the chemical index alteration(CIA)is 52.58-56.04,with an average value of 53.82,reflecting that the sandstones in the Xiufeng Formation was formed in the palaeoclimate environment with a low degree of chemical weathering.On the chondrite-normalized REE pattern,it is in a right-dipping pattern,and the distribution curve of HREE is flat,which is in good agreement with the curve of the active continental margin.The LREE/HREE values range from 3.74 to 5.73,the(La/Yb)N values range from 11.27 to 19.08,and theδEu values range from 0.59 to 0.98,showing a moderately weak negative Eu anomaly.The normalized REE distribution curves in the global average upper continental crust(UCC)are relatively flat,with the(La/Yb)UCC values ranging from 1.01 to 1.72 with an average of 1.26,and the(δEu)UCC values between 0.84-1.40 with an average of 1.13,which is close to the glo

关 键 词：绣峰组 年代学 地球化学 砂岩 物源区 构造环境 漠河盆地 大兴安岭 

分 类 号：P59[天文地球—地球化学]