内蒙古扎兰屯地区晚三叠世哈拉苏斑状正长花岗岩的成因:锆石U-Pb年龄、Hf同位素和地球化学证据  

Genesis of Late Triassic Harasu porphyritic syenogranite in Zalantun area,Inner Mongolia:Zircon U-Pb age,Hf isotope and geochemical evidence

作　　者：胡鹏 段明 熊金莲 曾威 刘行[1] 闫国强 魏佳林 HU Peng;DUAN Ming;XIONG Jinlian;ZENG Wei;LIU Xing;YAN Guoqiang;WEI Jialin(Tianjin Center,China Geological Survey(North China Center for Geoscience Innovation),Tianjin 300170,China;National Marine Data and Information Service,Tianjin 300171,China;China University of Geosciences,Wuhan 430074,Hubei,China;Jilin University,Changchun 130061,Jilin,China)

机构地区：[1]中国地质调查局天津地质调查中心(华北地质科技创新中心),天津300170 [2]国家海洋信息中心,天津300171 [3]中国地质大学,湖北武汉430074 [4]吉林大学,吉林长春130061

出　　处：《地质通报》2023年第12期2109-2120,共12页Geological Bulletin of China

基　　金：中国地质调查局项目《铀铁铜铝等战略性矿产资源调查》(编号:DD20230027);《华北豫西等重点成矿区带铝铜镍等矿产地质调查》(编号:DD20221686);《内蒙古阿拉善-河套地区区域地质调查》(编号:DD20211191)。

摘　　要：对内蒙古扎兰屯哈拉苏斑状正长花岗岩进行年代学、地球化学和Hf同位素组成研究。LA-ICP-MS锆石测年结果指示,哈拉苏斑状正长花岗岩于晚三叠世(213.17±0.93 Ma)侵位,矿物组合以石英、碱性长石和斜长石为主,富SiO_(2)(72.56%~74.36%)、K_(2) O(4.74%~5.49%),贫MgO(0.12%~0.34%)、CaO(0.54%~0.95%)、TiO_(2)(0.19%~0.29%)和P 2 O 5(0.042%~0.053%),A/CNK=1~1.05,小于1.1,强烈亏损Ba、Sr、Eu、P、Ti,表现出铝质A型花岗岩的矿物组合及地球化学特征。哈拉苏A型花岗岩具有高的εHf(t)值(+9.08~+15.3),可能源于新生中基性地壳物质的部分熔融。哈拉苏A型花岗岩形成于后碰撞构造环境。可能受古亚洲洋闭合的远程效应影响,扎兰屯地区地壳加厚并向后造山伸展机制转换,随后在晚三叠世形成了扎兰屯地区哈拉苏斑状正长花岗岩。In this paper,the geochronology,geochemistry and Hf isotopic composition of the Harasu porphyritic syenogranite in Zalantun,Inner Mongolia were studied.LA-ICP-MS zircon dating indicates that the Harasu porphyritic syenogranite was emplaced during the Late Triassic(213.17±0.93 Ma).The mineral assemblage is mainly composed of quartz,alkaline feldspar and plagioclase.The Harasu porphyritic syenogranite is characterized by high SiO_(2)(72.56%~74.36%),K_(2) O(4.74%~5.49%),low MgO(0.12%~0.34%),CaO(0.54%~0.95%),TiO_(2)(0.19%~0.29%)and P 2 O 5(0.042%~0.053%),A/CNK=1~1.05,<1.1.It is strongly depleted in Ba,Sr,Eu,P and Ti,showing the geochemical characteristics of aluminous A-type granite.The Harassu A-type granites have highεHf(t)values(+9.08~+15.3),which may due to the partial melting of new meso-basic crustal materials.The Harasu A-type granite is recognized as the product of a post-orogenic tectonic.The crust in Zalantun area was thickened and transformed into a post orogenic extension mechanism,which may be affected by the remote effect of the closure of the Paleo-Asian Ocean,and then the Late Triassic Harasu porphyritic syenogranite in Zalantun area was formed.

关 键 词：A型花岗岩 晚三叠世 地球化学 锆石U-PB测年 内蒙古扎兰屯 地质调查工程 

分 类 号：P534.51[天文地球—古生物学与地层学] P588.121[天文地球—地质学] P59