SEISMOLOGY AND GEOLOGY ›› 2016, Vol. 38 ›› Issue (2): 259-277.DOI: 10.3969/j.issn.0253-4967.2016.02.003

• Research Paper • Previous Articles     Next Articles

INFLUENCES OF OBLIQUITY ANGLE DIFFERENCE ON THE EVOLUTION OF FEN-WEI RIFT: A STUDY FROM SEGMENTED TRANSTENSION CLAY MODEL

ZHUO Yan-qun1, S. A. Bornyakov2, GUO Yan-shuang1,3, MA Jin1, S. I. Sherma2   

  1. 1. State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029, China;
    2. Institute of the Earth's Crust, Siberian Branch, Russian Academy of Sciences, St. 128 Lermontova, Irkutsk 664033, Russia;
    3. Department of Civil Engineering, University of Toronto, Toronto M5S1A4, Canada
  • Received:2015-03-18 Revised:2016-01-05 Online:2016-06-20 Published:2016-08-11

黏土实验模拟分段剪切拉张下的偏斜角差异对汾渭裂谷带形成演化的影响

卓燕群1, S. A. Bornyakov2, 郭彦双1,3, 马瑾1, S. I. Sherman2   

  1. 1. 中国地震局地质研究所, 地震动力学国家重点实验室, 北京 100029;
    2. Institute of the Earth's Crust, Siberian Branch, Russian Academy of Sciences, St. 128 Lermontova, Irkutsk 664033, Russia;
    3. Department of Civil Engineering, University of Toronto, Toronto M5S1A4, Canada
  • 作者简介:卓燕群,男,1986年生,2015年毕业于中国地震局地质研究所固体地球物理学专业,获博士学位,助理研究员,从事与地震相关的构造变形场实验研究,电话:010-62009010,E-mail:zhuoyq@163.com,zhuoyq@ies.ac.cn。
  • 基金资助:

    国家自然科学基金（41172180，41211120180，41511130029）、中国地震局地质研究所基本科研业务专项（IGCEA1525，IGCEA1203）与中国地震局“地震科技重点突破计划前期工作”项目和俄罗斯基础研究基金（120591161GFENa）共同资助。

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Abstract:

The Fen-Wei rift is composed of a series of Cenozoic graben basins, which extends in an S-shape and strikes mainly NNE. Two distinct types of basins are defined in the Fen-Wei rift. The NEE-striking basins(or basin system) are bounded by active faults of mainly normal slip while the NNE-striking basins are characterized by their dextral strike-slip boundary faults. The adjacent NEE-striking basins(or basin systems) are linked by the arrangement of NNE-striking basins and horsts that is called the linking zone in this study. The segmentation of the Fen-Wei rift shows that the geometry and the activity of different rift segments are varied. The southern and northern rift segments strike NEE and are characterized by tensile movement while the central rift segment strikes NNE with transtensional motion. Previous field surveys show that the ages of the Cenozoic basins in the Fen-Wei rift are old in the southern rift segment, medium in the northern rift segment, and young in the central rift segment. The sizes of linking zones are large in the central rift segment, medium in the northern rift segment, and small in the southern rift segment. In addition, the east tip of Xinding Basin propagates towards NEE along the northern rift segment and the west tip of the basin grows towards NNE, while the shape of Linfen Basin is almost antisymmetric with respect to the Xinding Basin. However, the previous laboratory or numerical simulations cannot explain these features because they didn't pay enough attention to the control of the rift segmentation on the evolution of NEE-striking basins and their linking zones. In this study, based on the previous field studies, we study the fracture process of a clay layer under the segmented dextral transtension of the basement. The spatiotemporal evolution of the deformation field of the clay layer is quantitatively analyzed via a digital image correlation method. The experiment reproduced the main architecture of the Fen-Wei rift. The results show that:(1) The chronological order of basin initiation and the different sizes of linking zones in deferent rift segments are caused by the different obliquity angles(the angle between the rift trend and the displacement direction between the opposite sides of the rift) among the southern, northern and central rift segments.(2) The interaction between adjacent NEE-striking basins leads to the formation of NNE-striking linking zones.(3) The interaction between adjacent rift segments may cause the special distribution of Xinding and Linfen Basins. Thus, we propose that the differences of the Fen-Wei rift segments are mainly controlled by the different obliquity angles. The lack of considering the influences of pre-exiting structures leads to the limited simulation of the details within the southern and northern segments of the Fen-Wei rift. Further studies may improve the model if this is taken into account.

Key words: obliquity angle, basin interaction, rift segment interaction, spatiotemporal evolution of deformation field, Fen-Wei rift

摘要：

汾渭裂谷带由2组走向不同的盆地组成：以拉张为主的NEE向盆地（或盆地系）和以右旋走滑为主的NNE向盆地。相邻NEE向盆地（或盆地系）间的连接区由NNE向盆地和地垒组成。汾渭裂谷带南、北段总体走向NEE并以拉张为主，中段总体走向NNE且具走滑兼拉张的性质。汾渭裂谷带各段具有以下特征：各裂谷段新生代盆地按照先南、再北、后中段的时间顺序形成；盆地连接区规模依中、北、南段递减；忻定盆地东端平行于裂谷带北段走向延伸成NEE向，西端沿逆时针方向旋转成NNE向，而临汾盆地与忻定盆地呈近似反对称的展布。但是已有模拟实验或数值实验均无法解释这些特征，原因在于它们忽略了裂谷分段性对NEE向盆地及其连接区演化的控制作用。文中结合已有地质调查资料，基于黏土实验和数字图像相关方法，观测了在基底的分段右旋剪切拉张作用下上覆黏土盖层的裂陷过程，并对黏土盖层表面的变形场时空演化进行了定量分析。实验再现了汾渭裂谷带的主要构造特征，结果表明：1）裂谷带南、北、中段偏斜角（裂谷带两侧块体的相对运动方向与裂谷带走向之间的夹角）的依次递减是造成NEE向盆地的形成时间和连接区规模在各裂谷段呈现上述特征的原因。2）相邻NEE向盆地的相互作用是形成具有右旋剪切拉张的NNE向连接区的原因。3）相邻裂谷段之间的相互作用可能是造成忻定盆地和临汾盆地特殊构造特征的原因。因此，汾渭裂谷带各段的构造差异主要源于各段偏斜角的差异。但模型还存在不足之处，其中值得进一步完善的是模型未考虑汾渭裂谷带先存构造的影响，因而未能详细模拟汾渭裂谷带南、北段内盆地的构造特征。

关键词: 偏斜角, 盆地相互作用, 裂谷段相互作用, 变形场时空演化, 汾渭裂谷带

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