Structural and geochronological constraints on the Mesozoic tectonic evolution of the North Dabashan zone, South Qinling, central China

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• 作者：Jianhua Li^a ; ^b ; ^{lijianhua0302@gmail.com} ; Yueqiao Zhang^a ; ^{yueqiao-zhang@sohu.com} ; Shuwen Dong^c ; Wei Shi^a
• 关键词：Structural geology ; 40Ar/39Ar geochronology ; Mesozoic ; Collisional orogeny ; Intra-continental orogeny ; Dabashan belt
• 刊名：Journal of Asian Earth Sciences
• 出版年：2013
• 出版时间：5 March, 2013
• 年：2013
• 卷：64
• 期：Complete
• 页码：99-114
• 全文大小：4614 K

文摘

Structural and ⁴⁰Ar/³⁹Ar data from the mylonitic rocks of the North Dabashan zone (NDZ) document kinematic and tectonothermal characteristics of the Mesozoic collisional and intra-continental orogenesis in the southern part of the Qinling orogenic belt. The NDZ underwent two deformational phases during the Mesozoic period. The earlier one is characterized by top-to-the-SW thrust ductile shearing along a NW-trending shear zone (DSZ-1), while the later one is featured by dextral strike-slip ductile shearing along another NNW-trending shear zone (DSZ-2). The timing of the two deformation events have been constrained to be 245-189 Ma and 178-143 Ma respectively, by using mica ⁴⁰Ar/³⁹Ar geochronology. It is proposed that the earlier deformation event was associated with the Middle Triassic-Early Jurassic collision between the North and South China Blocks, which generated the initial framework of the NDZ; and the later one was related to the Middle Jurassic to Early Cretaceous intra-continental orogeny in East Asia, which caused a significant eastward extrusion of the South Qinling and led to the formation of the SW-convex Dabashan foreland orocline. The distinguishing between these two deformation events sheds a new insight into the Mesozoic tectonic evolution of the Qinling orogenic belt.