WANG Yang JI Guangyi Key Laboratory of Isotope Geochronology and Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640 School of Earth Science and Mineral Resources, China University of Geosciences, Beijing, 100083 Geological Institute of Beijing Municipality, Beijing, 100011
Mesozoic volcanic rocks are widespread throughout the Great Xing’an Range,NE China.However,precise data constr...
Ji-Feng Ying~*,Xin-Hua Zhou,Lian-Chang Zhang,Fei Wang State Key Laboratory of Lithospheric Evolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,P.O.Box 9825,Beijing 100029,China
Ar-Ar dating results of late Mesozoic-Cenozoic volcanic rocks from the Yanji area, NE China provide a new volcano-sedimentary stratigraphic framework. The previously defined “Triassic-Jurassic” volcanic rocks (including those from Sanxianling, Tuntianying, Tianqiaoling and Jingouling Fms.) were erupted during 118―106 Ma, corresponding to Early Cretaceous. The new eruption age span is slightly younger than the main stage (130―120 Ma) of the extensive magmatism in the eastern Central Asian Orogenic Belt and its adjacent regions. Subduction-related adakites occurring in the previously defined Quanshuicun Fm. were extruded at ca. 55 Ma. Based on these new Ar-Ar ages, the late Mesozoic to Palaeocene volcano-sedimentary sequences is rebuilt as: Tuopangou Fm., Sanxianling/Tuntianying Fm. (118―115 Ma), Malugou/Tianqiaoling Fm. (K1), Huoshanyan/Jingouling Fm. (108―106 Ma), Changcai Fm. (K2), Quanshuicun Fm. (~55 Ma) and Dalazi Fm. Our results suggest that subduction of the Pa- laeo-Pacific Ocean beneath the East Asian continental margin occurred during 106 to 55 Ma, consistent with the paleomagnetic observations and magmatic records which indicated that the Izanagi-Farallon ridge subduction beneath the southwestern Japan took place during 95―65 Ma.
