The volcanic rocks from the Batamayineishan Formation in the Beisantai area are mainly composed of basalt, basaltic andesite, andesite and dacite, with minor volcaniclastic rocks. These rocks have low TiO2 and high Na2O, indicating characteristics of calc-alkaline series. Geochemical research result shows that they are characterized by LREE-enriched patterns with slightly negative Eu anomalies. The rocks have high large ion lithophile element（LILE）, and low high field strength element（HFSE）concentrations with strong negative Nb, Ta and Ti anomalies. From basic through intermediate to felsic, the depletions in Sr, Ti and P of the studied volcanic rocks increase gradually. These geochemical characteristics indicate that the volcanic rocks are products of mantle-derived magma related to oceanic subduction in an island-arc setting. The LA-ICP-MS zircon U-Pb dating of the andesite and the dacite yielded ages at 325～321 Ma and 310 Ma, respectively. In combination with the published age（300 Ma）of basalts from this formation, it is inferred that subduction of the Junggar ocean in eastern Junngar Basin lasted to the Late Carboniferous. Consequently, the final closure of the Junggar ocean occurred most likely after 310 Ma.
Chen Chunyong Wang Chong Luo Jinglan He Xianying Ma Shangwei Xu Xuelong Dai Jingjing Liu Yong. Zircon U-Pb ages and geochemical characteristics of the Carboniferous volcanic rocks in the Beisantai area, eastern Junggar and their tectonic implications[J]. Chinese Journal of Geology, 2018, 53(3): 1136-1156.