内蒙古东部钓鱼台地区火山岩年代学、地球化学特征及地质意义  

Geochronology,Geochemistry and Geological Significance of Volcanic Rocks in the Diaoyutai Area,Eastern Inner Mongolia

作　　者：王利 梁天意 WANG Li;LIANG Tianyi(Chemical Geological Prospecting Institute of Liaoning Province Co.LTD,Jinzhou121007,Liaoning,China)

机构地区：[1]辽宁省化工地质勘查院有限责任公司,辽宁锦州121007

出　　处：《西北地质》2025年第1期68-80,共13页Northwestern Geology

基　　金：中国地质调查局项目“内蒙古1∶5万钓鱼台等四幅区域地质调查”(DD20160201-07)资助。

摘　　要：笔者通过对内蒙古东部钓鱼台地区火山岩岩石学、年代学和地球化学等方面的研究,探讨该地区火山岩形成时代、岩浆来源及构造背景,为研究大兴安岭中段地区在中-晚侏罗世的岩浆活动和构造演化提供依据。笔者选取钓鱼台地区满克头鄂博组流纹质凝灰岩,系统地开展岩石学、LA-ICP-MS U-Pb测年和岩石地球化学等研究工作。根据研究结果显示,内蒙古东部钓鱼台地区的满克头鄂博组火山岩形成于中—晚侏罗世(160.3±2.2)Ma,火山岩SiO_(2)含量平均为74.98%,Al_(2)O_(3)含量平均为13.33%,CaO含量平均为0.82%,全碱(ALK)含量平均为6.96%,显示为高钾钙碱性系列岩石,稀土元素配分曲线为明显的右倾特征,轻稀土富集而重稀土亏损,轻重稀土分馏明显,Eu具有明显的负异常,岩石表现为富集Rb、Th、U、Nd等大离子亲石元素(LILE),亏损Nb、Sr、P、Ti等高场强元素(HFSE),与A型花岗岩的地球化学特征相似。结合区域地质资料和前人研究成果,研究区内满克头鄂博组火山岩岩浆主要来源于地壳的部分熔融,可能有地幔物质参与,产生于伸展构造背景下,推断与蒙古-鄂霍茨克洋闭合后板块俯冲后撤作用导致的岩石圈伸展作用有关。Through the study of the petrology,chronology and geochemistry of volcanic rocks in Diaoyutai area in Eastern Inner Mongolia,to discuss the formation age of volcanic rocks,the source of magma and the tectonic background in this area,and to provide a basis for studying the magmatic activity and tectonic evolution in the middle part of the Great Xing'an Range during the Mid-Late Jurassic.This paper selects rhyolite tuff from Manketouebo Formation in Diaoyutai area,Studies on petrology,LA-ICP-MS U-Pb dating and rock geochemistry have been carried out systematically.According to the research results,the volcanic rocks of the Manketouebo Formation in the Diaoyutai area of eastern Inner Mongolia were formed in the middle to Late Jurassic(160.3±2.2)Ma,The average SiO_(2) content of medium coarse monzogranite is 74.98%,the average Al_(2)O_(3) content is 13.33%,the average CaO content is 13.33%,the average total alkali(ALK)content is 6.96%,it shows high potassium calc-alkaline series rocks.The distribution curve of rare earth elements is right-leaning,with enrichment of light rare earth and deficit of heavy rare earth,significant fractionation of light and light rare earth,and Eu has obvious negative anomaly,the rocks are enriched in Rb、Th、U、Nd(LILE),and depleted in Nb、Sr、P、Ti(HFS),and the geochemical characteristics are similar to those of A-type granite.Combined with regional geological data and previous research results,the volcanic magma of the Manketouebo Formation in the study area is mainly derived from the partial melting of the crust,which may involve mantle material,and it should be generated in the extensional tectonic background.It is inferred that it is related to the lithosphere extension caused by the plate subduction and retraction after the closure of the Mongolian-Okhotsk Ocean.

关 键 词：大兴安岭中段 U-PB年代学 岩石地球化学 满克头鄂博组 构造背景 

分 类 号：P595[天文地球—地球化学] P588.12[天文地球—地质学]