Abstract:

Southeast coast of China lies in the plate junction between the Pacific and the Eurasian plates, where volcanic rocks are widely exposed and largescale mineralization were developed in the Mesozoic. There is a largescale distribution of acidic volcanic rocks while the mafic and  intermediate volcanic rocks are exposed sporadically.The acid and intermediate volcanic rocks, which are characterized by high alkali, high K, high Al and low Ti, belong to highK calcalkaline series while the mafic volcanic rocks which are characterized by high Si and low alkali belong to highmidK calcalkaline series. The REE fractionation and negative anomaly of europium are more and more obvious from mafic volcanic rocks to acidic volcanic rocks. The mafic volcanic rocks are depleted in Nb, Zr, Y and slightly enriched in Ba, Hf, Th, Ce. The acid and intermediate volcanic rocks are depleted in Ba, Ti, P, Nb, Zr, Ta, Sr and strongly enriched in Pb. The studies of major elements, trace elements and REE suggest that the source of mafic volcanic rocks is separated from the source of acidic volcanic rocks. The remelting of the lower crust caused by heat from basaltic underplating which was widespread in southeast coast of China in the Mesozoic generated a lot of acidic volcanic rocks. The intermediate volcanic rocks, geochemical characteristics of which are controlled by acid volcanic rocks, are generated by mixing of acid magma and mafic magma.

Key words: southeast coast of China, Mesozoic volcanic belt, geochemical characteristics