A Typical Sublithospheric Mantle beneath the Tello Region, SE-Ngaoundéré (Cameroon Line)  

作　　者：Nguihdama Dagwai Kamgang Pierre Mbowou GbambiéIsaac Bertrand Chazot Gilles Ngounouno Ismaïla 

机构地区：[1]École Normale Supérieure,Universitéde Maroua,Cameroun [2]Département des sciences de la Terre,Facultédes Sciences,Universitéde YaoundéI,Yaoundé,Cameroun [3]École de Géologie et d’Exploitation Minière(EGEM),Département de Mines et de la Géologie,Universitéde Ngaoundéré,Meiganga,Cameroun [4]UniversitéEuropéenne de Bretagne,Brest,France

出　　处：《Advances in Geological and Geotechnical Engineering Research》2022年第2期48-57,共10页地质与岩土工程研究进展（英文）

摘　　要：Peridotite xenoliths,raised to the surface by alkaline basalts or kimberlites,provide us direct information on the processes and composition of the upper mantle.They are the major source of information on the state of stress,pressure and temperature in the deep mantle.They are thus a source of petrological and geochemical information that is generally not available on the Earth’s surface.Fresh spinel-lherzolite xenoliths exhibit a protogranular components of the Tello volcano.The Tello is the continental sector of the Cameroon Line,located in the South East of the town of Ngaoundéréat 75 km approximately between(N7°13’,N7°14’)and(E13°40’and E13°60’).Minerals’composition of the xenoliths is~64%olivine,~24%orthopyroxene,~11%clinopyroxene and~1%spinel.Significant variation in(Cr/Cr+Al)of the system shows the reciprocal nature of the spinel solution.The Tello spinel lherzolites show internal chemical homogeneity and represent a normal upper mantle.Their mineral chemistries suggest equilibrium condition of 830°-925°and 1.4 GPa-2.3 GPa.These data suggest that there is good correlation bracket between increasing activity of Al2O3 and decreasing of practionning of TiO2 into spinel.The AlIV and AlVI contents vary by 0.05-0.2 and 0.03-0.2 respectively.The majority of samples caracterise the lithospheric mantle.

关 键 词：Spinel-Lherzolite xenoliths Protogranular Sublithospheric mantle Tello Cameroon line 

分 类 号：P58[天文地球—岩石学]