GEOCHEMISTRY OF TRIASSIC DEPOSITS IN EASTERN LINQING DEPRESSION AND ITS TECTONIC SIGNIFICANCE

The mineral composition of clastic sedimentary rocks is an important indicator to tectonic setting of the sediments. In this paper, we analyzed the major and trace elements of the Triassic clastic deposits sampled from the Eastern Linqing Depression. Results show that, the Triassic samples are mainly greywacke and arkose with low maturity. The parent rock of the clastic sedimentary rock is consistent with continental crust in general which mainly are sedimentary rocks and granite, and the Eastern Linqing Depression was a tectonic environment of active continental margin close to the continental island arc in Early-Middle Triassic Epoch. The dynamic mechanism can be connected to the subduction of the Qinling ocean crust beneath the North China plate in early stage and the collision between the Yangtze plate and North China plate later on. This study provides the geochemical evidence for determining the tectonic environment of the south side to the eastern North China in Triassic period.