Whole-rock geochemical, U-Pb and Sm-Nd isotope characteristics of the Dongueni Mont nepheline syenite intrusion, Mozambique  

作　　者：Vicente Albino Manjate 

机构地区：[1]Instituto Nacional de Minas, Av24 de Julho, 1895, Maputo, Mozambique

出　　处：《Geoscience Frontiers》2017年第5期1063-1071,共9页地学前缘（英文版）

基　　金：the fostering research institutions (Cnpq and PRO-AFRICA);the Mining and Geologic Institute for the financial help

摘　　要：The Dongueni Mont nepheline syenite intrudes migmatitic paragneisses and siliciclastic metasediments of the Barue Complex, Mozambique. This study reports the whole-rock geochemical, U-Pb and Nd isotopic data of the nepheline syenite. The ferroan and alkalic geochemical characteristics are typical of alkaline rocks formed in a within-plate setting. The strong depletion in high field strength elements(HFSEs)(e.g. Ba, Nb, P,and Ti) and enrichment in large ion lithophile elements(LILEs)(e.g. Rb, Th, K, and Pb) are consistent with magmatism in a continental alkaline magmatic province associated with intracontinental rifting. Zircon U-Pb data yielded crystallization ages from 498 ± 19 to 562± 14 Ma,consistent with the Pan-African Orogeny and the inherited zircons yield an age of 1040 Ma, which supports the presence of a Mesoproterozoic crust. Theε_(Nd)(t) values from the nepheline syenite samples range from-15.1 to-16.1 and the T_(DM)values from 1.77 to 1.67 Ga, which indicate that the initial nepheline syenite magma formed from a tholeiitic or mantle source in a within-plate setting with crustal assimilation.The Dongueni Mont nepheline syenite intrudes migmatitic paragneisses and siliciclastic metasediments of the Barue Complex, Mozambique. This study reports the whole-rock geochemical, U-Pb and Nd isotopic data of the nepheline syenite. The ferroan and alkalic geochemical characteristics are typical of alkaline rocks formed in a within-plate setting. The strong depletion in high field strength elements(HFSEs)(e.g. Ba, Nb, P,and Ti) and enrichment in large ion lithophile elements(LILEs)(e.g. Rb, Th, K, and Pb) are consistent with magmatism in a continental alkaline magmatic province associated with intracontinental rifting. Zircon U-Pb data yielded crystallization ages from 498 ± 19 to 562± 14 Ma,consistent with the Pan-African Orogeny and the inherited zircons yield an age of 1040 Ma, which supports the presence of a Mesoproterozoic crust. Theε_(Nd)(t) values from the nepheline syenite samples range from-15.1 to-16.1 and the T_(DM)values from 1.77 to 1.67 Ga, which indicate that the initial nepheline syenite magma formed from a tholeiitic or mantle source in a within-plate setting with crustal assimilation.

关 键 词：OROGENY GEOCHRONOLOGY Model age NEPHELINE SYENITE Crystallization 

分 类 号：P588.122[天文地球—岩石学] P597[天文地球—地质学]