The origin and compositions of Mesoarchean oceanic crust: Evidence from the 3075Â Ma Ivisaartoq greenstone belt, SW Greenland

In some areas gabbros include up to 15 cm long white inclusions (xenoliths). These inclusions are composed primarily (> 90%) of Ca-rich plagioclase and are interpreted as anorthositic cumulates brought to the surface by upwelling gabbroic magmas. The anorthositic cumulates have significantly higher initial εNd (+ 4.8 to + 6.0) values than the surrounding gabbroic matrix (+ 2.3 to + 2.8), consistent with different mantle sources for the two rock types.