Geochemistry of Neoproterozoic metavolcanic rocks from the Tahtai Logomiti area,Tigrai,Northern Ethiopia:Implication for petrogenesis and tectonic settings  

作　　者：Azeb Gebremicale Mulugeta Alene Teklay Gidey 

机构地区：[1]School of Earth Sciences,Mekelle University,P.O.Box:231,Mekelle,Ethiopia [2]School of Earth Sciences,Addis Ababa University,P.O.Box:1176,Addis Ababa,Ethiopia [3]Department of Earth,Environmental and Planetary Sciences,Case Western Reserve University,Cleveland,OH,USA [4]Faculty of Mines,Aksum University,P.O.Box:1010,Aksum,Ethiopia

出　　处：《Acta Geochimica》2025年第1期128-144,共17页地球化学学报(英文)

摘　　要：The Tahtai Logomiti area is characterized by metavolcanic and metavolcaniclastic interbedded with clastic and carbonate metasedimentary rocks of Neoproterozoic age.New geological,petrographic,major,and trace elements data were used to evaluate the metamorphism,petrogenesis,and paleo-tectonic setting of the area.The field and petrographic observation indicate that the area has undergone greenschist facies metamorphism.Based on mineralogy and geochemical attributes,these metavolcanic rocks are classified as basalt,basaltic-andesite,andesite,and dacite.The moderate degrees of light rare earth element(LREE)enrichment,flat heavy rare earth element(HREE)pattern,and low Nb/Y ratio,represent shallow mantle sources.In addition to that,the TiO_(2)/Yb vs.Nb/Yb diagram,high(La/Yb)N ratio(>3.44),indicates shallow melting and depleted magma sources.However,the high ratios of(Th/Ta)>3.8,(La/Ta)>38,and low ratios of(Th/La)<1,(Nb/La)<1,and high Pb content would indicate crustal contamination of the magma.The discrimination diagram and trace element ratios(Nb/Y,La/Sc,La/Y,and La/Th)indicate that the metavolcanic rocks have a calc-alkaline affinity.In addition,the ZrNb-Y and Th-Hf-Ta plots show that the rocks formed under a volcanic-arc setting.The general petrological and geochemical characteristics of the Tahtai Logomiti metavolcanic rocks suggest that the area is associated with subduction-related arc accretion of the Arabian Nubian Shield.

关 键 词：Deformation METAMORPHISM FOLIATION CALC-ALKALINE NEOPROTEROZOIC Arabian Nubian Shield 

分 类 号：P548[天文地球—构造地质学] P534.3[天文地球—地质学]