Characteristics of Volcanic Rocks and Tectonic Setting of Diagenesis of the Tanjianshan Group

The volcanic rocks of Tanjianshan group can be divided into two parts: the Volcanic clastics of the lower part(O1-2h)and the Lava subvolcanics of the upper part (O3y). Much research had been done from Rock combination, Rock chemistry, Geochemistry and so on. The volcanic rocks of the lower part appear a valley environment characteristic and the upper part presents the characteristic of a type of island arc environment. From descend upwards, the bimodal volcanic rocks turn into the type of island arc calcium alkaline volcanic ,which can indicate the tectonic setting of diagenesis that experienced a few stages from the formation of the continental rift, gradual stability, the ocean-continent subduction to the formation of a type of island arc volcanic.