| Late Triassic granite plutons in Qinling orogen have long been studied to constrain the timing and collisional processes between the North and South China blocks, and several contradictory geodynamic settings, subduction, syn-collision and post-collision, with a compressional or an extensional tectonics, were recently proposed by geochronological and geochemical works. In order to explore the emplacement mechanism and further to clarify the controversial correlation between emplacement and the regional tectonics, a multidisciplinary structural study was conducted on a typical Late Triassic pluton, the Baliping granitic pluton, and a Late Triassic shear zone, the Shagoujie shear zone, in East Qinling. Combined with the field observations, zircon U-Pb dating, and the structural geology studies, this thesis yields the following conclusions:(1)The protolith of Shagoujie augen granitic mylonite and the Baliping porphyaceous biotite monzogranite were generated by the cognate magma, the crystallization age of which is ca.220.1～223.2Ma. Meanwhile, the Shagou augen granitic mylonite yield210.1±1.5Ma for metamorphic age, representing the formation time of the shear zone.(2)The sinistral transpressional deformation controlled the final stage of the Baliping granitic pluton’s emplacement in the crust whereas the Shagoujie shear zone was formed due to the sinistral transtensional deformation during the cooling stage (220.1～210.1Ma) of the Baliping granitic pluton. The temporal and spatial coexistence of the two different deformation, transpression and transtension, are essentially the result of deformation partitioning along the curved Shandan belt due to the oblique convergence (the convergence direction is38°) between the North China and South China blocks.(3)Taken together, it reveals a plain fact that the Qinling orogen was still in the syn-collision tectonic setting during223.2～210.1Ma due to the oblique convergence between the North China and South China blocks. |
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