摘要
莫桑比克位于南部非洲,矿产资源极其丰富,是钛矿主要出口大国,目前主要开发利用的以海岸沿线的钛锆沙矿为主,钛铁矿原生矿的开发利用及其成矿地质背景研究程度相对较低。本文采集了莫桑比克太特省一带与原生钛铁矿共生的斜长岩系列分析样品,对斜长岩样品锆石U-Pb定年,获得岩石形成的地质年龄为580±5 Ma;样品岩石化学特征反映了斜长岩属低Ti、低Mg、低K拉斑玄武岩系列;稀土地球化学元素反映斜长石堆积明显,δEu出现极高的正异常;LREE/HREE比值为8.27~21.44,总体显示为轻稀土富集型稀土配分模式曲线,指示了斜长岩为深部原始地幔高度熔融及结晶分异而成;微量元素中具有明显的富集Rb、Sr、Ba等大离子亲石元素,亏损Zr、Nb等高场强元素,并且Ta/Hf比值为0.1~0.26,Th/Ta比值为3.14~13.59,反映斜长岩形成于陆内弧后伸展构造环境。通过对钛铁矿成矿围岩的研究,揭示了钛铁矿的成因类型为岩浆晚期结晶分异型,成矿模式为结晶分异压滤型;同时揭露了莫桑比克赞比西构造带660~610Ma泛非造山运动重要证据。
Mozambique is located in southern Africa.It is rich in mineral resources,and is one of the major export countries of titanium ore.Currently most industrial mining is based on the titanium zirconium sand ore along the coast.The primary ilmenite deposits are far less explored,and their geological background is largely unclear.A series of anorthosite samples closely related to the primary ilmenite have been collected in the Tete Province,Mozambique.Zircon U-Pb ages for the anorthosite samples are 580±5 Ma,which indicate the time of rock formation.The chemical characteristics of the samples indicate that the anorthosites are low Ti,low Mg and low K tholeiites.Rare earth elements show obvious accumulation of plagioclase,δEu shows extremely high positive anomaly;the LREE/HREE ratios are 8.27~21.44,which shows the enrichment of LREE,indicating that the anorthosites were formed by high-degree melting and crystallization differentiation of the primary mantle.The trace elements have obvious enrichment of Sr,Ba and other large-ion lithophile elements,as well as depletion of Zr,Nb and other high field strength elements.The Ta/Hf ratios are 0.1~0.26,Th/Ta ratios are 3.14~13.59,reflecting the formation of anorthosites in the continental retro-arc extensional tectonic environment.The study of the country rock of the ore-forming ilmenite has revealed that the genetic type of the ilmenite is late-stage magmatic crystallization differentiation,and the ore-forming model is crystallization,differentiation,pressure,filtration.Our data also show the important evidence of the 660~610 Ma Pan-African orogeny in the Zambezi tectonic zone in Mozambique.
作者
刘高峰
楼法生
罗春林
王斌
廖六根
卢先锋
陈浩鹏
朱昌杰
CUMBANE Antonio
刘永旭
LIU Gaofeng;LOU Fasheng;LUO Chunlin;WANG Bin;LIAO Liugen;LU Xianfeng;CHEN Haopeng;ZHU Changjie;CUMBANE Antonio;LIU Yongxu(Geological Survey Institute of Jiangxi Province,Nanchang,330030,China;Matola Bureau of Geology,Mineral Resources and Energy,Matola,1115,Mozambique;Coalfield Geological Research Institute of Jiangxi Province,Nanchang,330030,China)
出处
《地质学报》
EI
CAS
CSCD
北大核心
2021年第4期1100-1113,共14页
Acta Geologica Sinica
基金
2010年国外风险勘查资金项目资助的成果(编号:10141014B011)。
