| Xinyang-Yuanlong Larger scale Ductile Strike-Slip Shear Zone(XYDSZ),of the west Qinling north margin,is located in Tianshui area,Gansu province,and also lies in the NE margin of the Qinghai-Tibet Plateau,the geotectonic Setting lies at the junction of the Qilian orogenic belt and the North Qinling orogenic belt of the middle section of the Central Orogenic System of China,and also stretches over the S-N(Helanshan-Sichuan-Yunnan) tectonic belts in the central area of China,It occupies a superposed tectonic position,which is overlapped by the paleo-Asiatic tectonic domain,the Tethyan tectonic domain and the Pacific tectonic domain.Because it lies at the junction,the transition,transformation and connection sections of the Qilian orogenic belt and the Qinling orogenic belt,this region not only presents similarities with the two orogenic belts,but also many differences from them It is of vital scientific significance for us to study the multi-phase orogenic processes between the convergence and divergence of the North China plate and the Yangtze plate,the composition, configuration,structure,evolution and transformation of orogenic mechanism at the junction of orogenic belt position,also orogenic process and the dynamics,etc.All these involve a significant foundation for the geological issues of the China continental geotectonic framework and evolution,the continental orogenic belt and continental dynamics.According to the geometry,kinematics,structural petrology,mineralogy,isotopic chronology etc.researches which can gain some conclusions as below:1,That the plane structural geometry pattern and the distribution of stratum of research field indicated that the Qinling and Qilian are not simply connected and corresponded with each other,but the structural relationship showed a huge juxtaposition and conjoin. Xinyang-Yuanlong Shear Zone of the junction is a lager dextro-rotational ductile strike-slip shear zone,which subdivided both Qilian and Qinling structural units;2,According to the granitic mylonite's mineralogy,,microstructure,structural fabric and mineral assemblage characteristic,and integrating stratigraphy,regional geology and magmatic rock distribution suggested that the shear zone formed from middling-superficial level(＜15km) in mid-pressure-low-temperature greenschist facies,the pressure about 6kb,the temperature about 350-450℃;3,The LA-ICP-MS U-Pb zircon isotopic dating of granitic mylonites was carded out, which confirmed the ages are XYZ08=(935.5±3.1Ma),XYZ07=(978.5±4.8Ma) and YL02 =(914.7±7.6 Ma ) of the protolith,which are the neoproterozoic(Jinningian) products of the North China block and Yangtze block subduction-collision tectonic-magmatic thermal event;4,The Qilian and Qinling orogenic belts's junction is a complex overlay tectonic region undergone complexly differ times and levels tectogenetic influence.Based on stratigraphy and areal structure characteristic,and integrated,the biotite(40)Ar/39Ar isotopic dating results of predecessors confirm that the shear,zone,formed from lower carboniferous,was the hercynian movement result,which indicated Qilian-Qinling on strike-slip collage tectonic setting during eopaleozoic era;5,According the areal geology evolvement characteristic researches suggested the Qilian and Qinling belts's junction undergone five times major tectonic movements:①Paleoproterozoic Era is the metamorphosed basements formed and evolved stage;②Meso-neoproterozoic transition basements formed and evolved stage,Jinningian the North China block and Yangtze block were converged;③Eopaleozoic was the block structure evolve and Caledonian subduction-collision stage;④The intraplate extensional tectonics and the Qilian-Qinling orogenic belts's oblique collision strike-slip collage were occurred in Neopaleozoic-Triassic stage;⑤In Neozoic-Cenozoic stage mostly happened the intracontinental evolvement,which behaved as brittle fractural shear strike-slip,fault block activities,mountains uplift,basin subsidence.
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