Zircon chronological and geochemical constraints on the Late Mesozoic volcanic events in the southeastern margin of the Songliao Basin, NE China
松辽盆地东南缘晚中生代火山事件的锆石年代学与地球化学制约

The Late Mesozoic volcanic rocks are widely distributed in the Yingcheng Formation in southeastern margin of the Songliao Basin. SHRIMP zircon U-Pb dating gives ages between 117Ma and 110Ma for the volcanic rocks indicating that the volcanic succession formed around Aptian-Albian of the Early Cretaceous. Two stages of the volcanism can be identified according to the sedimentary interlayer. Petrographical and geochemical study shows that the early stage was characterized with acidic eruption, while the late stage mainly with medium-basic magmatism. All the rocks are mostly belong to high-K calc-alkaline series or sub-alkaline series. There is an intimate geochemical evolution relationship between the acidic and the medium-basic. Sr-Nd isotopic result indicates that these two volcanic successions were derived from the same magma source, a depleted mantle, and contaminated by the crust in different level during the period of ascending and evolving. Good determination on the volcanic events in the southeastern margin of the Songliao Basin is significant for the study of the Late Mesozoic volcanic activities in the Songliao Basin and correlation with magmatism in adjacent region.