地球物理学进展 ›› 2017, Vol. 32 ›› Issue (6): 2383-2393.doi: 10.6038/pg20170613

所属专题: 青藏高原

• 空间与固体地球物理 • 上一篇    下一篇

青藏高原东北缘岩石圈变形方式的动力学模拟研究

孙玉军1, 胡道功1, 张怀2, 范桃园1, 张耀玲1, 李冰1,3, 石耀霖2   

  1. 1. 中国地质科学院地质力学研究所, 北京 100081;
    2. 中国科学院计算地球动力学重点实验室, 中国科学院大学, 北京 100049;
    3. 中国地质科学院, 北京 100037
  • 收稿日期:2017-05-11 修回日期:2017-11-09 出版日期:2017-12-20 发布日期:2017-12-20
  • 通讯作者: 石耀霖,男,1944年生,教授,主要从事地球动力学研究.(E-mail:shiyl@ucas.ac.cn) E-mail:shiyl@ucas.ac.cn
  • 作者简介:孙玉军,男,1983年生,博士,副研究员,主要从事地球动力学数值模拟方面的研究.(E-mail:sunyujunabc@163.com)
  • 基金资助:

    国家自然科学基金项目(41641039,41590860,41574090)和中国地质调查项目(GZHL20120301,DD20160268-3)联合资助.

Numerical study on the dynamics of lithospheric deformation pattern in the northeastern Tibetan plateau

SUN Yu-jun1, HU Dao-gong1, ZHANG Huai2, FAN Tao-yuan1, ZHANG Yao-ling1, LI Bing1,3, SHI Yao-lin2   

  1. 1. Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China;
    2. Key Laboratory of Computational Geodynamics, Chinese Academy of Sciences, Beijing 100049, China;
    3. Chinese Academy of Geological Sciences, Beijing 100037, China
  • Received:2017-05-11 Revised:2017-11-09 Online:2017-12-20 Published:2017-12-20

摘要:

青藏高原东北缘是青藏高原横向扩展的前缘位置,其岩石圈变形方式和动力学机制是理解青藏高原横向扩展模式的关键.本研究利用数值模拟方法,以地表地形、岩石圈结构和地表热流等观测为约束,重点讨论了流变强度差异对青藏高原东北缘岩石圈变形方式的影响.结果表明:当青藏高原周缘地块岩石圈地幔强度相对较高,地壳强度相对较低的情况下,在不断扩展的青藏高原挤压作用下,周缘地块地壳增厚,增厚的地壳在重力作用下使得下覆岩石圈地幔俯冲下插;而当周缘地块岩石圈地幔强度非常高,则有限的地壳增厚不能使其俯冲下插,只能在地壳部分形成有限的缩短变形;低黏滞性、高速流动的下地壳使得下地壳整体增厚,从而对青藏高原地表的整体抬升有重要贡献,而对岩石圈地幔的变形方式影响有限.

Abstract:

The northeastern margin of the Tibetan plateau is the lateral expansion front of the Tibetan plateau. However, dynamic processes, such as lithospheric structure and strain localization, are still unclear. The lithospheric deformation pattern is critical to understand the dynamics of this region. In this study, taking the topography, lithospheric structure and heat flow as constraints, we discussed the effect of rheological contrasts on the lithospheric deformation. The results indicate that when the strength of mantle lithosphere is relatively high and the strength of crust is relatively low beneath this region, the crust is thickened under the continuous compression of the Tibetan plateau. The mantle lithosphere may subduct beneath the Tibetan plateau under the gravity of thickening crust. However, when the strength of mantle lithosphere is very high (rigid), the mantle lithosphere may not subduct beneath the Tibetan plateau. In this case, the plastic deformation focuses in the crust. When the lower crust of the Tibetan plateau has low viscosity and high velocity, the thickened lower crust may lead to the whole uplift of the Tibetan plateau. Thus, weak and high velocity lower crust plays an important role for the high and flat Tibetan plateau. However, the effect of lower crust in this case on the deformation of mantle lithosphere is limited.

中图分类号: