摘要
Deweras群位于太古界津巴布韦克拉通的西北边缘Magondi沉积变质带内,岩性主要为变质陆相沉积岩和玄武岩,是古元古界地壳运动形成大陆边缘裂谷盆地相。出露在南部的Deweras群沉积岩和基性火山岩与北中部能进行较好的对比。通过分析Deweras群变质玄武岩的地球化学元素含量,分别使用不活泼痕量元素比值Zr/TiO2与SiO2、Nb/Y与SiO2两对参数统计,认为Silverside地区的变质玄武岩属于亚碱性玄武岩。各种微量元素分布模式和比值参数相图分析也表明:位于变质带南部即Munyati,Mupfure和Alaska地区的基性熔岩与变质带北中部Doma西部地区角闪岩岩席特征一致,此处变质玄武岩均是幔源型原始岩浆演化成因。
Deweras Group, belonging to the Magondi Belt at the northwest rim of Archean Zimbabwe Craton, is composed of the metamorphic rocks of continental sediments and basalts deposited in a rift-related basin margin environment marked by crustal movement in the Palaeoproterozoic.The sediments and basic volcanic rocks of this group, occurring in the southern part of the belt, show a good stratigraphic correlation with those between the northern and middle part of the belt. Through the analysis of the elements in the metabasalt, using the immbole trace elements Zr/TiO2 versus SiO2 and Nb/Y versus SiO2 of whole rock geochemical data, the Deweras Metabasalt of the Silverside area were classified as subalkaline basalts, in addition various trace elements have a similar distribution of their values.The plot coincides with that of Deweras basic lavas of the Munyati, Mupfure and Alaska （southern part of the belt） and amphibolite sills in Doma West area （northern and middle parts of the belt）. They are characterised by a similar trend of their primitive-mantle normalised element patterns.
出处
《地质调查与研究》
2007年第3期161-167,共7页
Geological Survey and Research
基金
中央财政国外矿产资源风险勘查专项资金项目(财建[2005]897)
