THE PETROCHEMISTRY AND TECTONICS OF LATE TRIASSIC TUMUGOU FORMATIONIN ZHONGDIAN

In this paper, we have a study on the trace element and REE of the Late Triassic Tumugou Formation deep water turbidite and arc volcanic rock in Eastern Zhongdian with the mineral composition statistics of Dickinson(1983). According to the statistics of mineral composition of 40 samples of sandstone, the plotted points are within the area of recycled orogen. The characteristics of trace element and REE are close to the continental island arc area in diagram. According to the characteristics and the related diagram of major element, they are close to the active continental margin and island arc environment, which are same as the tectonic environment of volcanic rock. The Tumugou Formation is an island arc volcanic-sedimentary rock series formed in the transition process from a passive continental margin to an active continental margin of the eastern margin of Zhongdian fold zone.