Trace Element Geochemistry of Cenozoic Volcanic Rocks in Shandong Province

The Cenozoic volcanic rocks of Shandong Province are mainly alkatic and strongly alkalic basaltic rocks.The contents of major and trace elements including transitional,incompatible and rare-earth ele- ments were determined.The chemical characteristics of major and trace elements indicate that these basaltic rocks were derived from a mantle source and probably represent a primary magma,i.e.,unmodified partical melts of mantle peridotite,in terms of Mg values,correlations between P_2O_5 and Ce,Sr,Ni and Rb concentrations,mantle xenoliths,etc.The abundances of trace elements vary systematically from west to east.The compatible transition elements such as Co,Ni,and Cr show a remarkable deple- tion,whereas the incompatible and rare-earth elements are abundant as viewed from the chondrite-nor- malized patterns.The chemical composition and correlation are consistent with the tectonic setting. According to the batch and fractional partial melting theory,the trace elem(?)nt contents of Shandong volcanic rocks can be calculated from the two-component mixing model.