福建泉州晚中生代伸展构造变形特征与年代学制约

晚中生代福建沿海地区发育多期与古太平洋板块俯冲有关的岩浆活动和构造变形.福建泉州地区伸展构造变形主要表现为高角度正断层和低角度正断层或拆离断层, 古构造应力场反演指示其形成于NW-SE向伸展环境.锆石U-Pb年代学指示泉州地区发育4期岩浆活动, 分别为晚侏罗世(~155 Ma)、早白垩世中期(130~125 Ma)、早白垩世末期(~109 Ma)以及晚白垩世早期(~100 Ma之后).结合构造变形的切割关系和岩浆岩年代学, 长乐-南澳剪切带左旋韧性走滑形成于130~120 Ma, 而右旋脆性剪切形成于120~100 Ma之间.古太平洋板块向华南大陆之下的俯冲角度变化导致福建沿海地区发育晚中生代造山带.造山作用开始于早白垩世之初, 结束于早白垩世末期, 以大规模NW-SE向伸展构造发育为标志, 其从同造山挤压到后造山伸展的转换发生于~120 Ma. 

Deformation Characteristics and Geochronological Constraints of Late Mesozoic Extensional Structures in Quanzhou,Fujian Province

Multi-stage Late Mesozoic magmatism and structural deformation related to the subduction of Paleo-Pacific plate occurred in the coast of Fujian Province, southeastern China. Extensional deformation in Quanzhou area presents high-angular normal faults and low-angular normal faults or detachment faults. The extensional deformation developed in NW-striking extensional setting. Zircon U-Pb geochronological data in this study suggest that Late Jurassic (~155 Ma), middle Early Cretaceous (130-125 Ma), late Early Cretaceous (~109 Ma) and early Late Cretaceous magmatic rocks outcrop in Quanzhou area. The comprehensive analyses of cutting relations and geochronological data of magmatic rocks show that the sinistral ductile strike-slip of the Changle-Nan'ao shear zone occurred in 130-120 Ma, whereas the dextral brittle shear developed between 120 Ma and 100 Ma. The angular variations of subduction for the Paleo-Pacific plate underneath the South China led to the development of the Late Mesozoic orogenic belt in the coast of Fujian Province. This orogen commenced at the beginning of Early Cretaceous and terminated in the latest Early Cretaceous, which is marked by the extensive NW-striking extensional structures. The transform from syn-orogen compression to post-orogen extension occurred at ~120 Ma.