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| 南秦岭构造带中段晚中生代陆内变形特征与侧向挤出构造 | |
| 引用本文： | 陈虹,胡健民,武国利,田蜜.南秦岭构造带中段晚中生代陆内变形特征与侧向挤出构造[J].吉林大学学报(地球科学版),2014,44(6):1906-1927. |
| 作者姓名： | 陈虹 胡健民 武国利 田蜜 |
| 作者单位： | 1.中国地质科学院地质力学研究所，北京100081; 2.国土资源部古地磁与古构造重建重点实验室，北京100081; 3.中国科学院地质与地球物理研究所，北京100029; 4.中国石化石油勘探开发研究院无锡石油地质研究所，江苏 无锡214126 |
| 基金项目： | 国家自然科学基金项目，中国地质调查局地质调查工作项目 |
| 摘 要： | 南秦岭构造带位于秦岭造山带南部，在中生代时期经历了复杂的陆内变形过程。在晚中生代阶段，南秦岭构造带内发育一系列平行造山带的走滑断裂带。目前对于这些走滑断裂带不同构造位置的变形特征、变形叠加关系以及动力学机制等方面的认识并不充分。构造研究显示，南秦岭构造带内的宁陕断裂和安康断裂均发育大量平行于断裂带的A型褶皱群和近水平的拉伸线理，表明南秦岭构造带经历了以走滑剪切变形为主的构造阶段。运动学特征表明，宁陕断裂以左行剪切变形为主，而安康断裂则以右行变形为特征。选择典型岩石样品进行同位素测年来限定断裂活动的时代，其中:宁陕断裂带内同构造花岗岩脉的锆石SHRIMP U-Pb定年结果为（186.0±4.0） Ma；安康断裂带内云母矿物的40Ar-39Ar定年结果为161.2~173.5 Ma。虽然宁陕断裂和安康断裂的运动方向不同，但是同位素年代学研究限定了两条断裂发生走滑变形的时间都是早-中侏罗世，从而共同构成了南秦岭构造带中间块体整体向东挤出的构造特征。同时也表明，相互碰撞的大陆在碰撞之后将很快转变为以平行造山带侧向挤出和走滑位移为主的陆内变形演化阶段。 |
| 关 键 词： | 南秦岭构造带 陆内变形 侧向挤出 宁陕断裂 安康断裂 秦岭造山带 |
| 收稿时间： | 2014-10-14 |
Late Mesozoic Intra-Continental Deformation and Lateral Extrusion in Central Segment of Southern Qinling Belt |
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| Chen Hong,Hu Jianmin,Wu Guoli,Tian Mi.Late Mesozoic Intra-Continental Deformation and Lateral Extrusion in Central Segment of Southern Qinling Belt[J].Journal of Jilin Unviersity:Earth Science Edition,2014,44(6):1906-1927. | |
| Authors: | Chen Hong Hu Jianmin Wu Guoli Tian Mi |
| Institution: | 1.Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing100081，China; 2.Key Laboratory of Paleomagnetism and Tectonic Reconstruction，Ministry of Land and Resources, Beijing100081, China; 3.Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing100029，China; 4.Wuxi Research Institute of Petrolem Geology, China Petroleum, Chemical Corporation, Wuxi214126，Jiangsu，China |
| Abstract: | Southern Qinling belt is located in the south part of the Qinling orogen, which experienced the complex intra-continental deformation in Mesozoic. In the Late Mesozoic period, there were a series of strike-slip faults developed along the orogen in the southern Qinling belt. At present, the understanding of the deformation features, superposition relationship and dynamic mechanism for these strike-slip faults on different location is not sufficient. Structural studies show that the Ningshan fault and the Ankang fault are characterized by the A type fold and sub horizontal stretching lineation, which indicated the southern Qinling belt underwent a tectonic stage dominated with the strike-slip shear deformation. Kinematic studies revealed the Ningshan fault was characterized by a sinistral shear deformation, while the Ankang fault by dextral characteristics. We chose the typical rock samples for isotopic dating to limit the fault activity time. The zircon SHRIMP U-Pb age of the syn-tectonic granite vein in the Ningshan fault was (186.0±4.0) Ma, and the mica 40Ar-39Ar dating results in the Ankang fault are 161.2-173.5 Ma. Although the kinematic features are opposite between the Ningshan fault and the Ankang fault, the geochronological results defined that the deformation time of these two faults is the same, e.g. Early-Middle Jurassic, both of which constitute a eastward extrusion for the central block of southern Qinling belt. This tectonic characteristic also indicated that the deformation of the orogen was soon transformed into the intra-continental deformation stage, which was dominant with the lateral extrusion and strike-slip displacement along the orogen. |
| Keywords: | southern Qinling belt intra-continental deformation lateral extrusion Ningshan fault Ankang fault Qinling orogen |
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