长白山火山碎屑喷出物和熔岩地球化学特征及其对构造环境的指示意义  

Geochemical characteristics of volcaniclastic ejecta and lava in Changbai Mountain and its implications for tectonic environment

作　　者：陈海潮 王璞珺 衣健[2] 武成智[3] 王寒非 孙松 王文华[2] CHEN Hai-chao;WANG Pu-jun;YI Jian;WU Cheng-zhi;WANG Han-fei;SUN Song;WANG Wen-hua(Key Laboratory for Evolution of Past Life and Environment in Northeast Asia(Jilin University),Ministry of Education,Changchun 130061,China;College of Earth Sciences,Jilin University,Changchun 130061,China;Changbaishan-Tianchi Volcano Observatory of Jilin Province,Antu 133600,Jilin,China;Department of Computer Science,Nanjing University,Nanjing 210023,China)

机构地区：[1]东北亚生物演化与环境教育部重点实验室(吉林大学),长春130061 [2]吉林大学地球科学学院,长春130061 [3]吉林省长白山天池火山监测站,吉林安图133600 [4]南京大学计算机科学与技术系,南京210023

出　　处：《世界地质》2020年第2期294-305,共12页World Geology

基　　金：国家自然科学基金项目(41472304,41790453);吉林省科技厅科技发展计划项目(20170101001JC)联合资助。

摘　　要：选取长白山火山碎屑喷出物(火山灰)和熔岩(浮岩、碱流岩、黑曜岩),对其进行岩石地球化学分析以确定其源区、演化过程和构造环境。研究表明,长白山火山碎屑喷出物和熔岩属于钾玄岩系列和高钾钙碱性系列,富K2O+Na2O,并具有高K2O以及较高的Fe2O3含量,低CaO、MgO、TiO2、P2O5和MnO含量,Mg#值变化范围为0.02~0.10,A/CNK的平均值为0.82,属于偏铝质岩石,稀土元素(REE)相对富集,轻重稀土分异强烈、轻稀土(LREE)相对富集、重稀土(HREE)亏损,铕负异常[δ(Eu)=0.04~0.15],大离子亲石元素(LILE)K、Sr、Ba等相对亏损,高场强元素(HFSE)Th、U、Ta、Nb、Hf相对富集,P、Ti等强烈亏损,Rb/Sr比值为3.23~93.33,在岩浆岩成因类型判别图上,所有样品均落在A型花岗岩区域内,说明其具有A型花岗岩成分特征。根据前人研究成果和本文所述的地球化学分析结果,可以说明长白山火山碎屑喷出物和熔岩可能起源于幔源岩浆的分异演化,在上侵时混染了地壳组分。长白山火山碎屑喷出物和熔岩形成于非造山板内拉张环境。The volcaniclastic ejecta(volcanic ash)and lava(pumice,alkali flow,obsidian)of Changbai Mountain were selected for rock geochemical analysis to determine their source area,evolution process and tectonic environment.Studies show that volcaniclastic ejecta and lava belong to the potassium basalt series and high-potassium calc-alkaline series,which are rich in K 2O+Na 2O,with high K 2O and Fe 2O 3 content,low CaO,MgO,TiO 2,P 2O 5 and MnO content.The Mg#values range from 0.02 to 0.10,and the average value of A/CNK is 0.82,which belongs to metaluminous rocks.The rare earth elements(REE)are relatively enriched,light rare earth elements(LREE)and heavy rare earth elements(HREE)are strongly differentiated.LREE are relatively enriched,while HREE are depleted.δEu is negative anomaly(0.04~0.15).The large ion lithophile elements(LILE)such as K,Sr,Ba are depleted relatively,and the high field strength elements(HFSE)such as Th,U,Ta,Nb,Hf are relatively enriched,with P and Ti strongly depleted.The ratio of Rb/Sr is 3.23~93.33.On the genetic type discrimination map of magmatic rocks,all samples fall on the area of A-type granite,indicating that they have the characteristics of A-type granite composition.According to the previous research and the geochemical analysis results in this study,it is indicated that the volcaniclastic ejecta and lava of Changbai Mountain may originate from the differential evolution of mantle-derived magma,which was subsequently mixed with the crustal components during the upwelling.Its forming environment is a non-orogenic intraplate stretching environment.

关 键 词：火山碎屑喷出物 熔岩 长白山 地球化学 构造环境 

分 类 号：P588.14[天文地球—岩石学] P588.21[天文地球—地质学]