| 阿拉善地块东缘新生代中新世挤压变形及动力学背景 |
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| 引用本文： | 赵衡,张进,曲军峰,张北航,牛鹏飞,惠洁,云龙,李岩峰,王艳楠,张义平.阿拉善地块东缘新生代中新世挤压变形及动力学背景[J].地球科学,2020,45(4):1337-1361. |
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| 作者姓名： | 赵衡 张进 曲军峰 张北航 牛鹏飞 惠洁 云龙 李岩峰 王艳楠 张义平 |
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| 作者单位： | 1.中国地质科学院地质研究所, 北京 100037 |
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| 基金项目： | 国家重点研究开发项目2017YFC0601301国家自然科学基金项目41572190中国地质调查局项目12120115069601 |
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| 摘 要： | 在阿拉善地块东缘发现新生代中新世挤压构造，形成近SN或NE-SW走向的逆冲断层及卷入新生代地层的褶皱.其形成背景关系到阿拉善地块新生代的变形特征以及与青藏高原扩展的关系.为了进一步探讨阿拉善地块东缘的挤压构造是否受青藏高原扩展控制，为青藏高原北缘新生代扩展过程的研究提供资料，通过详细地质填图、区域地质调查与对比方法，确定了这些挤压构造的几何样式以及运动学特征，结合断层滑动矢量，恢复出变形时的古应力场.室内外的分析表明，形成这些挤压构造的最大主应力方位为NW-SE或近EW向，结合盆地地震反射资料、卷入构造的地层，推测变形的时代是中新世中晚期.这期变形的动力可能是阿拉善地块受到青藏高原北缘的挤压向东运动所致.同时在阿拉善地块向东运动的过程中，其内部发育的早期东西向构造带发生右行走滑，和阿拉善东缘的挤压构造一同调节地块的变形.晚中新世之后，高原东北缘最大主应力方位发生顺时针旋转，阿拉善东缘挤压构造被后期构造叠加.
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| 关 键 词： | 阿拉善 中新世 陆内变形 印度-欧亚碰撞 青藏高原 构造 |
| 收稿时间： | 2019-05-26 |
Characteristics and Dynamic Background of Cenozoic Compressive Structures in Eastern Margin of Alxa Block |
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| Abstract: | A Cenozoic compressive belt, which is manifested by near SN or NE-SW trending thrust faults or folds, was observed in the eastern margin of the Alxa block. The compressive belt is vital to the understanding of the deformation pattern of the Alxa block as well as its relationship with the propagation of the northeast Tibetan plateau. To better understand how these compressive structures were controlled by the growth of Tibetan plateau, field mapping and regional comparison along the eastern margin of the Alxa block were carried out. By analyzing the geometric and kinematic characteristics of these structures in the Cenozoic strata, the paleo-stress field which shows that these structures were governed by the NW-SE or near EW compression regime was rebuilt by us. Together with seismic profile and the strata involved in the compressive zone, it tentatively interprets the formation of the compressive belt was formed in the Middle-Late Miocene. The dynamics of this event could be attributed to the eastward extrusion of the Alxa block caused by the intense push from the Tibetan plateau during Miocene, which indicates the northeastward Tibetan plateau growth. Meanwhile, dextral slip faults are accommodation faults developed on the pre-existing basement foliations, together with the eastern compressive belt, to adjust the eastward movement of the Alxa block. During the Middle to Late Miocene, the northeastern plateau was subjected to intense NE-oriented compression, after which the maximum principal stress demonstrated a clockwise rotation. The compressive structures along the eastern margin of Alxa were replaced by later structures. |
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