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Compression–Right Lateral Shear Ductile Deformation Of Kanggur Ductile Deformation Zone In Eastern Tianshan Mountains,and Its Geochronological Constraints

Posted on:2020-04-08Degree:MasterType:Thesis
Country:ChinaCandidate:J HuFull Text:PDF
GTID:2370330575476152Subject:Structural geology
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The Kanggur ductile deformation zone of eastern Tianshan mountains is distributed in the east-west direction between the Kanggur fault and Yamansu fault.Present studies indicate that the it has two stages of different ductile formation,early ductile compressional,and later right lateral shear,but had distinct ideas about the deformation time.The ductile deformation of extrusion-strike-slip phases was recorded and preserved in the deformation rocks of Carboniferous sedimental-volcanic series and syntectonic magmatic are distributed along the deformation zone.In this paper,we carry out the macrostructure analysis,microstructure observation,finite strain measurement and quartz c-axis fabric?EBSD?analysis for the deformation rocks of Carboniferous sedimental-volcanic series and syntectonic magmatic,in order to identifies different types of structural deformation in the two stages of extrusion-strike-slip.Moreover,we did a chronological analysis in the zircon U-Pb of the syntectonic rock mass and biotite 40Ar/39Ar dating from the western part of the deformation zone.The tectonic environment of the Kanggur ductile deformation zone is discussed,furthermore,it provides important evidence for the tectonic evolution of the central Asian ancient ocean basin after its closure.The analysis results indicates,different type features of macro-micro structural and mineral fabric are show within different tectonic deformation stages.In the ductile compressional deformation,deformation is occurred in the Carboniferous sedimentary-volcanic rock series and intrusive rock mass before 285 Ma,the macro-micro structural suggest that the symmetry phenomenon.In the right lateral,?1?Carboniferous sedimentary-volcanic rock series and early-middle Permian intrusive rocks both are deformed;?2?The morphology of syntectonic rock mass indicates a right lateral shear?e.g.,Huangshandong,Huangshanxi,Xiangshan and Jingxia,etc.?;?3?The structural phenomenon show that the kinematic by S-C fabric,boudinage structure,foliation,lineation,asymmetric porphyroid and domino structure,etc.;?4?ductile deformation of extrusion-strike-slip phases was occurred in the Carboniferous sedimental-volcanic series,early ductile compressional superimposed later right lateral shear.Systematic measurement of the finite strains of quartz and triaxial strain rate in mylonites indicates that the strain type in general compression is L-S and LS tectonites.Combined with the deformation behavior of quartz,feldspar and quartz C axis EBSD fabric analysis,the results show that the early middle temperature?500550??is formed by N-S direction compression,and the later superimposed low temperature?400??is led to E-S right lateral ductile shearing.Results of zircon U-Pb and biotite 40Ar/39Ar dating,and combined with regional tectonic,the early extrusion ductile deformation of kanggur ductile deformation zone was formed in 300285 Ma,which was related to the intracon tinental extrusion after collision between Tarim plate and middle Tianshan plate;The right lateral shear was originated in post-collisional extensional setting.
Keywords/Search Tags:Kanggur ductile deformation zone, EBSD, Finite strain, 40Ar/39Ar, U-Pb age
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