内蒙古满都拉地区索伦缝合带多期变形年代学

索伦缝合带是古亚洲洋构造演化的重要界线，其构造变形特征能为理解洋盆俯冲、碰撞拼合和陆内调整过程提供必要约束。索伦缝合带在满都拉地区出露杂乱堆积（无序）、浊积岩、火山岩和海陆交互相沉积岩等岩石构造单元，记录了多期次叠加变形作用。野外露头观察、构造要素测量和构造叠加样式显示3期构造变形：D1期变形主要发育在浊积岩单元中，以轴向SW-NE同斜紧闭褶皱为特征；D2期发育近ESE-WNW走向逆冲推覆构造，并伴随一系列断层相关褶皱；D3期形成区域上NE走向左行走滑断层，切割前两期变形。本研究拟采用云母40Ar/39Ar和锆石LA-ICP-MS U-Pb年代学方法，研究韧性剪切带内糜棱岩和云母片岩，及与构造带存在切割关系的变形和未变形花岗岩年代，结合构造变形几何学和运动学分析，探讨多期变形与造山带构造运动的关系，恢复古亚洲洋晚古生代构造演化动力学过程。

Structural and kinematic analysis of the Solonker suture zone will provide essential constraints on the Palaeo-Asian oceanic crust subduction, subsequent collision and intracontinental tectonism. The Mandula area is located within the Solonker suture zone and crops out chaotic assemblage, turbidite unit, volcanic rock unit and marine-terrigenous sediment unit. They experienced a polyphase deformation during the Late Paleozoic, but insufficient studied by now. Three phases of deformation are recognized by field observations, measurement of foliation and lineation and analysis of superimposed structures. D1 is mainly preserved in the turbidite unit is characterized by a series of isoclinal folds with fold axes striking SW-NE. D2 is developed in all litho-tectonic units and is characterized by ESE-WNW striking thrust faults and a series of fault-related folds. D3 is characterized by the development of regional NE striking strike-slip faults, which crosscut the previous two generations of structures. Each phase of deformation is in need of precise age constraints. A further probe into the relationship between the polyphase deformation and geodynamics is necessary. This study will focus on the geochronology of each phase of structural deformation. Mylonitic rock and mica schist from the shear zone related to each tectonic event will be collected for 40Ar/39Ar dating, with care taken to ensure that the mineral grains to be dated grew during the specific deformation event being analyzed. The deformed/undeformed granitic rock cut by/cutting a certain fault or shear zone will be taken for zircon U-Pb dating to determine the age of fault activity. The structural and geochronologic data will construct the relative deformation order in the Mandula area, reveal the Late Paleozoic geodynamic scenario in the study area, and give a few insights for the tectonic evolutional processes about accretionary orogens.