摘要: Classification of xenoliths The late Cenozoic alkali basalt includes abundant mafic to ultramafic xenoliths. These xenoliths were divided into igneous and granoblastic types, based on the petrographical textures. The two textural types also are discriminated clearly by trace element and isotope compositions. The igneous-type xenoliths are relatively enriched in highly incompatible elements and depleted in Sr and Nd isotope compositions (*’sr/“sr; 0.70457~ 0.70498, ma;-1.5~ 0.1) compared with those of the granoblastic type (87Sr/“Sr; 0.70578~ 0.70826, sNd:-5.4~-2.9). The granoblastic-type xenoliths have slightly low Pb isotope compositions (206Pb/204Pb: 17.72~ 17.93) compared with those of the igneous type (206Pb/2 4Pb: 17.86~ 18.5).Formation of the lower crust beneath Oki-Dogo The isotope compositions of the igneous-type samples are close to the compositions of the late Cenozoic alkali basalt …