Late Mesozoic kinematics history of the two major fault zones (the Zhaoyuan-Pingdu and the Muping-Jimo ones)in the Jiaobei uplift has been studied based on field observations,fault kinematics analysis and paleostress inversion.These were combined with isotopic dating results of volcanic and granitic rocks from this region by using 40Ar-39Ar,SHRIMP and LA-ICPMS techniques,in order to determine the timing of main tectono-magmatic events and the change in tectonic stress regimes.The results show that the Jiaobei uplift experienced the change in tectonic stress regime from Late Jurassic compression to Early Cretaceous extension.Late Jurassic NW-SE compression resulted in crustal thickening and massive emplacements of crustal-derived S-type granites;their ages indicate two thermal events:one occurring in 160~150 Ma,and the other in 147~142 Ma.The deformation was characterized by both low-angle reverse faulting and left-lateral strike-slip faulting along the NNE-striking fault zones in the Jiaobei uplift.During the Early Cretaceous,tectonic stress regime was changed and dominated by NW-SE to NWW-SEE extension.This extension caused the formation of the Jiaolai basin,induced widespread I-A type granite intrusion(aged in 135~106 Ma)and intermediate to acid volcanic activity.40Ar-39Ar hornblendes and SHRIMP zircon U-Pb dating of a basaltic volcanic layer which was found to be intercalated in the lower section of the Early Cretaceous Laiyang Group,indicate that Early Cretaceous extension initiated at ca.130 Ma.Finally discuss geodynamic settings for the change in late Mesozoic tectonic stress regime from compression to extension.
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张田.2008.胶北隆起晚中生代构造-岩浆演化历史[J].地质学报,82(9):1210-1228. Zhang Tian.2008. Late Mesozoic tectono-magmatic evolution history of the Jiaobei uplift,Jiaodong peninsular[J]. Acta Geologica Sinica,82(9):1210-1228.