The discovery of Middle Jurassic volcanic rocks in northern Fujian Province and its geological significance

There are only very few Middle Jurassic volcanic rocks exposed along the southeast coast of China, but they are very important for the study of the regional Mesozoic tectonic magmatic activiy and tectonic evolution. The authors discovered for the first time the Middle Jurassic volcanic rocks in the Tieshan area of Zhenghe during the survey of large area of Cretaceous volcanic rocks in northern Fujian Province. The zircon U-Pb age obtained by LA-ICP-MS technique is 173.63±0.80Ma. The volcanic rocks are welded tuff, belonging to the calc-alkaline series. Geochemical data show that they are peraluminous rocks rich in potassium and large ion lithophile elements but poor in high field strength elements. Therefore, these rocks must have been formed in a continental margin arc environment, related to the subduction of the paleo-Pacific plate.