Evidence of zircon U-Pb dating and rock geochemical characteristics of Badangshan volcanic rocks and metamorphic quartz diorite on the northern margin of North China craton

Metamorphic quartz diorite intruded into the the Badangshan volcanic rocks in Langjunhala area, eastern Chifeng City. LAICP-MS zircon U-Pb dating technique constrained the age of schistosity rhyolite and quartz diorite. The results show that the ages of schistosity rhyolite and quartz diorite are 387.6±2.8Ma and 387.1±2.3Ma, aindicating the Middle Devonian magmatic activity. According to the geochemical characteristics of foliated rhyolite with high silicon, alkali, aluminum, iron, magnesium, calcium and poor peraluminous characteristics, the rocks belong to the calc alkaline series. The light and heavy REE fractionation is weak and the Eu has weak negative anomaly. The foliated rhyolite has lower Ti/Y and Zr/Y ratios, implying the source of lithospheric mantle. Metamorphic quartz diorite is characterized by high aluminium, iron, magnesium, calcium and peraluminous, belonging to calcalkaline series magma. The fractionation of light and heavy rare earth elements is weak, with weak negative Eu anomaly. The metamorphic quartz diorite is enriched in large ion lithophile elements and depleted in high field strength elements. It has obvious negative anomalies of Ta, Nb and Y, implying mixed source characteristics of crust and mantle. Tectonic environment discriminations show that it formed on the active continental margin and was the product of subduction of the oceanic plate, probably related to the extensional environment after the collision between the Bainaimiao island arc and the northern margin of the North China craton.