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The ductile deformation Characteristics of Caledonian Intracontinental Orogeny in the Northeastern Jiangshan-Shaoxing Tectonic Zone:Insights from Magnetic Fabric Study and Its Geodynamic Implication

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Acta Geologica Sinica(English Edition) 2016年第1期90卷 75-87页

作者： GONG Genhui CHEN Hanlin WANG Fang LIN Xiubin MENG Lifeng Departement of Earth Sciences Zhejiang University Research Center of Structures in Oil and Gas Bearing Basin Ministry of Education

The Jiangshan-Shaoxing tectonic zone was the northeastern boundary between the Yangtze Block and the Cathaysia Block during the Neoproterozoic and was an intracontinental orogenic belt during late of the early Paleozoic. In this tectonic zone, there develops a lot of mylonite underwent strong ductile deformation and schist, gneiss, and amphibolite with medium and high grade metamorphism which was formed during the late of early Paleozoic. The research of geometry and kinematic of ductile deformation in Jiangshan-Shaoxing tectonic zone is very important to reveal the tectonic process of intracontinental orogeny. This paper uses the anisotropy of magnetic susceptibility （AMS） to determine the ductile deformation geometry and kinematic of Jiangshan-Shaoxing tectonic zone combing with the field survey. In this study, 190 specimens of 19 locations and 221 specimens of 23 locations from Wangjiazhai section and Lipu-Sizhai section were analyzed. The magnetic foliation over magnetic lineation in both Wangjiazhai and Lipu-Sizhai sections together with the field observations indicated a compressional deformation pattern. 3 and 4 strong ductile deformation zones can be established in the Wangjiazhai section and the Lipu-Sizhai section, respectively. According to the magnetic fabric and petro-fabric studies, the Northeastern Jiangshan-Shaoxing tectonic zone suffered two kinds of deformation patterns during the late early Paleozoic, i.e., the thrusting deformation followed by sinistral shear deformation.

关键词： magnetic fabric ductile deformation deformation intensity deformation pattern Jiangshan-Shaoxing tectonic zone

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Paleozoic Accretion-Collision Events and Kinematics of ductile deformation in the Eastern Part of the Southern-Central Tianshan Belt, China

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Acta Geologica Sinica(English Edition) 2002年第3期76卷 308-323页

作者：舒良树 J.Charvet 卢华复 S.C.LAURENT Department of Earth Sciences and State Key Laboratory of Metallization Nanjing University Nanjing 210093 China UMR 6530 CNRS FR009 Departement des Sciences de la Terre Université d'Orléans 45067 Orléans France

The Tianshan range could have been built by both late Early Paleozoicaccretion and Late Paleozoic collision events. The late Early Paleozoic Aqqikkudug-Weiya suture ismarked by Ordovician ophiolitic melange and a Silurian flysch sequence, high-pressure metamorphicrelics, and mylonitized rocks. The Central Tianshan belt could principally be an Ordovician volcanicarc; whereas the South Tianshan belt, a back-arc basin. Macro- and microstructures, along withunconformities, provide some kinematic and chronological constraints on 2-phase ductile *** earlier ductile deformation occurring at ca. 400 Ma was marked by north-verging ductileshearing, yielding granulite-bearing ophiolitic melange blocks and garnet-pyroxene-facies ductiledeformation, and the later deformation, a dextral strike-slip tectonic process, occurred during theLate Carboniferous-Early Permian. Early Carboniferous molasses were deposited unconformably onpre-Carboniferous metamorphic and ductilely sheared rocks, implying the end of the early *** large-scale ductile strike-slip along the Aqqikkudug-Weiya zone was possibly caused by thesecond tectonic event, the Hercynian collision between the northern Tarim block and the southernSiberian block. Late Paleozoic granitic magmatism and superimposed structures overprinted this EarlyPaleozoic deformation belt. Results of geometric and kinematic studies suggest that the primaryframework of the Southern-Central Tianshan belt, at least the eastern part of the Tianshan belt, wasbuilt by these two phases of accretion events.

关键词： kinematics ductile deformation collision-accretion Paleozoic Southern-Central Tianshan belt

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Strain Localized deformation Variation of a Small-Scale ductile Shear Zone

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Journal of Earth Science 2023年第2期34卷 409-430页

作者： Lefan Zhan Shuyun Cao Yanlong Dong Wenyuan Li State Key Laboratory of Geological Processes and Mineral Resources China University of GeosciencesWuhan 430074China

A continental-scale strike-slip shear zone frequently presents a long-lasting deformation and physical expression of strain localization in a middle to lower crustal ***,the deformation evolution of strain localization at a small-scale remains *** study investigatedductile shear zones exhibit a typical transition from protomylonite,mylonite to extremely deformed ultramylonite,and decreasing mineral size from coarse-grained aggregates to extremely fine-grained mixed *** sense indicators such as hornblende and feldspar porphyroclasts in the shear zone are the more significantly low-strain zone of *** microstructure and EBSD results revealed that the small-scale shear zone experienced ductile deformation under medium-high temperature *** aggregates suggested a consistent temperature with an irregular feature,exhibiting a dominated high-temperature prism slip ***,coarse-grained aggregates in the mylonite of the shear zone were deformed predominantly by dislocation creep,while ultra-plastic flow by viscous grain boundary sliding was an essential deformation process in the extremely fine-grained(~50μm)mixed-phases in the ***-derived strain rates calculated from quartz paleopiezometry were on the order of 10^(-15) to 10^(-13) s^(-1)from low-strain mylonite to high strained *** localization and strain ratelimited process was fluid-assisted precipitation presenting transitions of compositions as hydrous retrogression of hornblende to mica during increasing deformation and ***,the potential occurrence of the small-scale shear zone was initiated at a middle-deep crust seated crustal condition dominated by the temperature-controlled formation and rheological weakening.

关键词： strain localization ductile deformation ultramylonite microstructure EBSD texture Gaoligong shear zone

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On the material dependence of experimental shear fracture orientation

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Science China Earth Sciences 2015年第12期58卷 2357-2362页

作者： Enrique GOMEZ-RIVAS Albert GRIERA Department of Geology and Petroleum Geology School of Geosciences King’s College University of Aberdeen Departament de Geologia Universitat Autònoma de Barcelona

It is not uncommon to observe shear fractures in ductile rocks oriented at more than 45° with respect to the maximum compression direction. Since these orientations cannot be explained with the classic Mohr-Coulumb or Tresca yield criteria, Zheng et al.(Journal of Structural Geology, 35: 1394–1405, 2011) proposed the maximum effective moment(MEM) failure criterion. This rule suggests that shear fractures in ductile rocks form at ?55° with the maximum compression axis and that this orientation is material-independent and, therefore, universal. Zheng et al.(Science China: Earth Sciences, 57(11): 2819–2824, 2014) used data from our own experiments as supporting evidence of their failure criterion. In this contribution we discuss why shear fracture formation in ductile rocks indeed strongly depends on the mechanical properties of the deforming medium, and why experimental data should not be taken to prove the validity of the MEM criterion. The formation mechanisms and orientations of shear fractures in our experiments significantly vary depending on the material strength and degree and type of anisotropy(composite and intrinsic). We therefore demonstrate using experimental data that a universal failure angle in ductile and anisotropic rocks does not apply. Additionally, we highlight some inconsistencies of the MEM criterion.

关键词： shear fracture anisotropy fracture orientation material properties failure criteria ductile deformation

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Triassic polyphase deformation in the Feidong-Zhangbaling Massif(eastern China) and its place in the collision between the North China and South China blocks

Triassic polyphase deformation in the Feidong-Zhangbaling Ma...

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中国科学院地质与地球物理研究所2004学术年会

作者： Michel Faure Patrick Monie Dominique Panis Institut des Sciences de la Terre d'Orleans UMR CNRS 6113Batiment GeosciencesUniversite d'Orleans45067 Orleans Cedex 2France

The Feidong-Zhangbaling Massif is located between the Dabieshan and Sulu areas along the Tan-Lu fault in eastern *** tectonicmetamorphic events are distinguished *** earliest deformation(D1) corresponds to a southward compression that occurred during subduction of the South China Block below the North China ***-to-the-south shearing is coeval with Late Permian-Early Triassic blueschist fades metamorphism,and possibly with the development of south-verging recumbent folds in the Neoproterozoic-Paleozoic sedimentary cover of the South China *** main ductile deformation(D2) is an extensional one,characterized by top-to-the-north shearing,coeval with the early stage of exhumation of the high-pressure rocks.A top-to-the-NW ductile shearing,and microfolds overturned to the northwest,belong to a second deformational phase of exhumation(D3) which is distinct from the main event(D2).Previous Ar-Ar mica dates ranging between 245 and 212 Ma suggest Late Permian-Early Triassic ages for the D1 to D3 *** D4 event produced NE-SW trending folds in the sedimentary cover interpreted as gravity collapse structures.A Late Cretaceous brittle extensional event(D5) controls the opening and infill of continental *** the study area,the Tan-Lu fault is a Cretaceous brittle normal *** lack of ductile deformation presented along the Tan-Lu fault suggests that it did not play a significant role in the exhumation of high-pressure metamorphic rocks.

关键词： Structural analysis ductile deformation Qinling-Dabie orogen Permian-Triassic tectonics Eastern China

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