| 中国东部及邻区晚中生代伸展拆离构造——综述与新认识 |
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| 引用本文：杨谦,施炜,侯贵廷.2019.中国东部及邻区晚中生代伸展拆离构造——综述与新认识[J].地球学报,40(4):511-544. |
| DOI：10.3975/cagsb.2019.012301 |
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| 基金项目:国家重点研发计划项目(编号: 2017YFC0601402);中国地质科学院地质力学研究所基本科研业务费专项项目(编号: DZLXJK201712) |
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| 中文摘要:伸展构造是大陆岩石圈减薄破坏在上部浅层的一种重要表现。其中, 低角度伸展拆离构造为中国东部以及邻区晚中生代地壳伸展变形的显著构造变形样式, 是研究区域岩石圈浅层构造变形与深部减薄过程关系的重要窗口。结合相关的几何学、运动学、年代学等资料的综述分析, 本文对中国东部及邻区低角度伸展拆离构造时空展布、运动学极性、应变机制进行了系统论述。在空间展布上, 这些伸展拆离构造在东亚大陆的分布不均一, 指示岩石圈的不均匀伸展减薄作用。在形成时代上, 伸展拆离活动主要集中在两个时代区间: 140–125 Ma为伸展拆离构造在中下地壳初始形成期, 在水平伸展作用主导下, 以简单剪切为主; 125–110 Ma为伸展拆离构造快速隆升剥露期, 在垂向挤压的主导下, 以纯剪切为主。相关的几何学和运动学标志表明这些伸展构造总体具有在NW–SE方向上单向低角度伸展拆离运动学特征, 反映它们总体受NW–SE向伸展应力场作用控制。以大兴安岭—太行山—武陵山重力梯度带为界, 东、西两侧区域伸展活动均具有从NW向SE传播的趋势, 且这种趋势西部较东部明显, 表现为不同的动力学背景特征。东部主要受到古太平洋板块后撤影响, 而西部可能与蒙古—鄂霍茨克洋闭合之后, 增厚地壳发生重力崩塌而引发区域大规模伸展活动以及同时发生的秦岭—大别构造带陆内造山后应力伸展的联合作用相关。 |
| 中文关键词:东亚大陆 伸展拆离构造 重力梯度带 应变机制 岩石圈减薄 古太平洋板块 |
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| Late Mesozoic Extensional Detachment Structures in Eastern China and Adjacent Areas: Overview and New Insight |
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| Abstract:Extensional structures constitute an important deformation form in the upper shallow layer of continental lithosphere thinning and destruction. Among them, the low angle extensional detachment structure which is the remarkable tectonic deformation style of Late Mesozoic crust extension in eastern China and adjacent areas is the key to studying the relationship between the deformation characteristics of the shallow layer in lithosphere and its deep layer activity process. Combined with related data of geometry, kinematics and chronology, the authors made a systematic exposition of spatial and temporal distribution, kinematic polarity and strain mechanism of low angle extensional detachment structures in eastern China and adjacent areas in this paper. The spatial distribution of these extensional detachment structures in East Asia continent is not homogeneous and this indicates uneven stretching and thinning of the lithosphere. As for the formation ages, stretching activities were mainly concentrated in two periods: 140–125 Ma was the initial formation stage of these extensional detachment structures in the middle-lower crust and the main deformation mechanism was simple shear which was controlled by horizontal extension; 125–110 Ma was the rapid uplift and erosion stage and the main deformation mechanism was pure shear which was dominated by vertical compression. Relevant marks of kinematics and geometry show that these extensional structures have the characteristics of one-way low angle extensional detachment in the NW–SE direction, implying the effect of uniform NW–SE extension stress field. The stretching activities in east and west regions were separated by Da Hinggan Ling–Taihang Mountain–Wuling Mountain gravity lineament and both had the tendency of spreading from NW to SE, but the west area was more visible than the east one and it also represented the different geodynamic settings. The east part was mainly affected by the retreat of the ancient Pacific plate. The west region might be related to the combined effects of the large-scale stretching activities resulting from the gravitational collapse in thickening crust after the closure of Mongolia–Okhotsk and the stress extension after intra-continental orogeny of Qinling–Dabie belt. |
| keywords:East Asia continent extensional detachment structures gravity lineament strain mechanism lithospheric thinning paleo-Pacific plate |
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