Abstract:Objectives: Mount Yunmeng Area, Beijing locates in the middle part of Yanshan Orogeny, the northern margin of the North China Craton (NCC). In this area, there are many Mesozoic magmatic activities, the E—Wtrending thrust Sihetang shear zone, and NEtrending extensional Dashuiyu shear zone. Although, many isotopic dating works have been done for these plutons and movements, there are less works to organize these data to describe their period relationship systematically and discuss their indication to the evolution of the Yunmengshan Metamorphic Core Complex (YMCC) and NCC.Methods: The zircon isotopic dating and single mineral (hornblende and biotite) 40Ar/39Ar dating are analyzed in this work. The cooling rates around the Mount Yunmeng are calculated and discussed.Results: Through the Zircon UPb isotopic dating, the ages of plutons are defined. The 206 Ma comes from the trapped magma zircon. Among the exposed rock masses, Shatuozi pluton is 159~151 Ma, Shicheng Pluton 169~151 Ma, Changyuan Pluton 156~151 Ma, Yunmengshan batholith 146~141 Ma, Fengjiayu—Xibailianyu granite pluton 130~124 Ma, Fengjiayu diorite pluton 127 Ma, Dadonggou granite pluton 127 Ma. Combined with the results of 40Ar/39Ar dating, the cooling rates are calculated. During the development of Sihetang shear zone, the cooling rate of the western, northern and eastern part of the YMCC is 76.92℃/Ma, 50.2℃/Ma and 13.7℃/Ma separately. During the development of Dashuiyu shear zone, they are 18.31℃/Ma, 6.13℃/Ma and 28.57℃/Ma separately. At the late of the development of YMCC, it is 50.0℃/Ma.Conclusions:The time of Mesozoic magmatic activities and tectonic movements in Yunmenshan area, and the cooling rate around the Yunmengshan batholith in different tectonic evolution stages are worked out. We figure out that there are three stages of magmatic activities: Late Triassic, Late Jurassic and Early Cretaceous. Besides, the Yunmengshan Area suffers three time significant tectonic events. In Early Jurassic, it behaves as the regional angular unconformity in the Yunmengshan area. There are less magmatic activities with the compress movements. In the earlier of Early Cretaceous (143~135.5 Ma), the Sihetang shear zone develops along the northern margin of the Yuanmengshan batholith. In the later of Early Cretaceous, (135~93.9 Ma), the Yunmengshan metamorphic core complex with the Dashuiyu shear zone as the detachment shear zone, develops along the southeastern margin. The northern and western margins of the Yuanmengshan batholith are affected by the Sihetang shear zone and have the higher cooling rate. At the early stage, the eastern margin is less affected by the Sihetang shear zone, with the smaller cooling rate, and mainly behaves the slow isostatic uplift. While at the late stage, with the high influence of the Dashuiyu shear zone, it is of the quick uplift. As a result, in Mesozoic, the Yunmengshan area has suffered many stages magmatic activities and tectonic movements, and it has the different cooling rates in different areas.