摘要
林西县前地村地区斑状石英闪长岩是区内与成矿密切相关的花岗岩类。本文应用系统岩石地球化学特征研究方法,在借鉴前人同位素测年研究成果的基础上,对本区斑状石英闪长岩的成因类型、岩浆物质来源及其形成的构造环境进行了初步研究。结果显示其岩石化学成分具高钾、低钠,富镁铁而贫硅铝,属于高钾钙碱性系列岩石,具有I型花岗岩的特点。微量元素显示富集Rb、Sr、Ba、U等大离子亲石元素,亏损K、Th、Nb、Ta、P等高场强元素,稀土元素呈现出曲线斜率较大,轻稀土富集、重稀土亏损的右倾分布模式,Eu显示为正常型或弱正Eu异常。岩石成因为基性岩的部分熔融所形成,其形成的构造环境为古俯冲带构造环境,锆石U-Pb表面年龄为239Ma,表明区内斑状石英闪长岩的形成可能与西伯利亚板块及华北板块间南北俯冲碰撞增生造山作用有关。
The porphyritic quartz diorite in Qingdi area of Linxi County,Inner Mongolia is a kind of granite closely related to mineralization.In this paper,the genetic types,the source of magma,and the geotectonic setting of formation of the porphyritic quartz diorite in this area are preliminarily studied by the characteristics of rock geochemistry,and the results of previous studies on isotopic dating.The results show that the rocks are of characteriscts of high K,low Na,rich in Mg-Fe and poor in Si-Al.They belong to the rocks with high K calc alkaline series and have the characteristics of I-type granite.The large ionic lithoophile trace elements such as Rb,Sr,Ba,and U were enriched,and the high field strength elements such as K,Th,Nb,Ta and P are depleted,REE present a right-leaning distribution pattern showing the large curve slope with enrichment of light rare earth elements and depletion of heavy rare earth elements.Eu shows normal or weakly positive Europium Anomaly.The rocks are formed by partially melting of basic rocks in a tectonic setting of paleosubduction zones.The U-Pb apparent age of Zircon is 239Ma,it is suggested that the formation of the porphyritic quartz diorite may be related to the subduction and accretion orogeny between the Siberia plate and the North-china plate in North-south direction.
作者
信铁军
Xin Tiejun(Chemical Geological Prospecting Institute of Liaoning Province Co.,Ltd,Jinzhou,Liaoning,121000,China)
出处
《化工矿产地质》
CAS
2024年第2期97-106,共10页
Geology of Chemical Minerals
关键词
斑状石英闪长岩
成因
构造环境
林西
大兴安岭中南段
Porphyrtic Quartz Diorite
Origin
Tectonic setting
Linxi County
Mid-Southern Greater Hinggan
作者简介
信铁军(1971~),男,主要从事固体矿产地质勘查工作,高级工程师。E-mail:275590291@qq.com。
