摘要
【研究目的】卢帕地体是坦桑尼亚第二大金矿集区所在地,对于其形成时代及成因机制争议较大。【研究方法】本次通过锆石年代学和地球化学特征分析,厘定卢帕地体花岗岩的形成时代和成因机制。【研究结果】锆石U-Pb年代学研究表明卢帕地体内花岗岩有两类:新太古代花岗岩类,年龄为2663±22 Ma~2778±13 Ma;古元古代花岗岩年龄为1944±10 Ma~2006±10 Ma,地球化学特征与I型花岗岩相似。卢帕地体内分布的其它基性岩、碳酸岩等代表了罗迪尼亚超大陆裂解开始的时间。【结论】岩石地球化学特征表明非A型花岗岩,其物质来源并非来自地幔,而是地壳重熔的结果。花岗岩构造环境判别图解显示,样品投影落在火山弧花岗岩中,花岗岩集中于大陆花岗岩区域,远离大洋花岗岩、大洋玄武岩和辉长岩区域,新太古代与古元古代的花岗岩形成于大陆边缘弧。
This paper is the result of rock geochemistry.[Objective]Lupa terrane is the second largest gold ore concentration area in Tanzania,and its formation age and genetic mechanism are controversy.[Methods]Through the analysis of zircon geochronology and geochemical characteristics of granite,the formation age and genetic mechanism of the Lupa terrane granite are determined.[Results]Zircon U-Pb geochronology studies indicate that there are two types of granites in the Lupa terrane:Neoarchean granites(2663±22 Ma~2778±13 Ma);Paleoproterozoic granite(1944±10 Ma~2006±10 Ma),and their geochemical characteristics are similar to those of I-type granite.The other basic rocks,carbonates and other rocks distributed within the earth represent the beginning of the breakup of the Rodinian super continent.[Conclusions]The geochemical characteristics of rocks indicate that the material source of non-A-type granite is not from the mantle,but the result of crustal remelting.The tectonic environment discrimination diagram of the granite shows that the sample projection falls in the volcanic arc granite,and the granite is concentrated in the continental granite area,away from the oceanic granite,oceanic basalt and gabbro area.The Neoarchean and Paleoproterozoic granites were formed in the continental margin arc.
作者
何胜飞
刘晓阳
孙凯
许康康
龚鹏辉
HE Shengfei;LIU Xiaoyang;SUN Kai;XU Kangkang;GONG Penghui(Tianjin Centre,China Geological Survey(North China Center for Geoscience Innovation),Tianjin 300170,China;Southern African Mining Research Insititute,China Geological Survey,Tianjin 300170,China)
出处
《华北地质》
2024年第3期14-22,35,共10页
North China Geology
基金
中国地质调查项目“非洲中东部7国矿产资源潜力评价项目(DD20160108)”
“非洲中东部大型铜钴资源基地评价(DD20190439)”
“南部非洲国际合作地质调查(DD20221801,DD20230125)”。
