Features and origin of inclusions in the Jiliuhe granite, northeastern Inner Mongolia,China

Monzogranite and granodiorite are distributed in a NE direction along both banks of Jiliu River in the Along Mountains area,northeastern Inner Mongolia. Many dark- colored microgranular mafic inclusions occur in these rocks. The in- clusions have typical magmatic and quench textures and contain acicular apatite, and some inclusions contain K- feldspar and quartz megacrystals of host rocks. The inclusions are mainly rounded in shape,showing pronounced plastic rheological charac- ters. They usually have a clear- cut contact relationship with the host rocks and sometimes transition or foggy contacts are also seen. The host rocks are rich in Si and K and exhibit the characteristics of magmatic evolution. Inclusions are rich in Mg,Fe and Ca and poor in Si,Al,and Na with Na>K. The rare earth element (REE)and trace element patterns for the inclu- sions and their host rocks are similar and both show an asymmetric, right- inclined LREE- enriched shape. Inclusions exhibit weak Eu depletion, while host rocks moderate- weak Eu depletion. Inclusions and host rocks display similarities in respect to geochemistry as well as non- cognate characters. These features indicate that dark inclusions in the Early Carboniferous Jiliuhe granites are the product of magma mixing and partly represent the basic end- member of mixed magma.