郭颖星
中国地震局地球物理研究所, 北京 100081
基金项目: 国家自然科学基金面上项目（41974103）资助
详细信息
作者简介: 朱涛, 中国地震局地球物理研究所研究员, 博士生导师, 主要从事地幔动力学模拟以及电阻率层析成像方法和应用研究.E-mail: zhutao@cea-igp.ac.cn
中图分类号: P315;P313 收稿日期:2020-10-27
修回日期:2021-03-31
上线日期:2021-08-10
Lithospheric basal shear traction and strain rate beneath Mainland China constrained by uppermantle shear-wave splitting anisotropy
ZHU Tao,GUO YingXing
Institute of Geophysics, China Earthquake Administration, Beijing 100081, China
MSC: P315;P313
--> Received Date: 27 October 2020
Revised Date: 31 March 2021
Available Online: 10 August 2021
摘要
摘要:地幔对流在岩石圈底部产生的剪切拖曳力和应变率的估计有助于理解和认识板块构造运动、岩石圈变形特征和应力分布格局、地壳长期运动状态和克拉通演化的深部动力学环境，但准确地估计它们是一个挑战.本文利用核相剪切波分裂各向异性约束下获得的全球和区域地震速度结构"耦合"的地幔对流模型计算了中国大陆岩石圈底部的剪切拖曳力和应变率.结果表明，与地幔对流速度相比，剪切拖曳力和应变率具有更加复杂的分布格局；剪切拖曳力的大小位于前人估计的范围之内，但其最大值明显较小，不超过4.0 MPa.中国西部的剪切拖曳力明显大于东部；剪切应变率不超过45/100 Ma；地幔黏度的横向变化可能会导致剪切拖曳力与剪切应变率呈负相关关系.
关键词: 数值模拟/
地幔对流/
剪切应力/
剪切应变率
Abstract:Estimation of shear traction and strain rate at the base of the lithosphere due to mantle convection is very helpful to understand the deep geodynamic environment of plate motions, lithospheric deformation and stress pattern, long-term crustal motion and cratonic evolution, howbeit estimating them precisely remains challenging. In this paper, we use global and regional seismic tomography-based mantle flow models to compute the lithospheric basal shear traction and strain rate beneath Mainland China under the constraints of core-refracted shear-wave splitting anisotropy. Our results indicate that, compared with convective velocity, lithospheric basal shear traction and strain rate has more complex pattern; the magnitude of shear traction lies in the range of previous estimations, but has a smaller upper limit that is not above 4.0 MPa; Shear traction beneath the western China is significantly greater than that beneath the eastern China; lithospheric basal shear strain rate is not greater than 45/100 Ma beneath Mainland China; laterally variable mantle viscosity could lead to an inverse relationship between shear traction and shear strain rate.
Key words:Numerical modeling/
Mantle convection/
Shear stress/
Shear strain rate
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