Estimating the lithospheric flexure of a plate with non-uniform flexural rigidity: a quantitative modelling approach
Estimating the lithospheric flexure of a plate with non-uniform flexural rigidity: a quantitative modelling approach
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估计具有非均匀弯曲刚度的板块的岩石圈弯曲：定量建模方法
DOI：
10.1186/s40623-021-01497-y
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发表时间：
2021
影响因子：
3
通讯作者：
Gao Jin-Yao
中科院分区：
文献类型：
--
作者：
Xu Ming-Ju;Wu Zhao-Cai;Ji Fei;Ruan Ai-Guo;Li Chun-Feng;Gao Jin-Yao
岩石圈变形是板块构造的一个基本过程。因此，确定岩石圈如何对地质负荷作出反应以更好地理解构造过程是至关重要的。岩石圈可以被模拟成一个薄而有弹性的板块在长期地质时间尺度上的弯曲（10 ~ 10 ~ 5年）。正交各向异性板挠度的偏微分方程间接用于计算理论导纳和相干性，然后将其与观测到的导纳和相干性进行比较，以反演板的非均匀弯曲刚度（或有效弹性厚度，T e）。然而，由于经典岩石圈模型可能高估了板块的挠度，精确恢复可变岩石圈挠度的过程仍然没有解决。这里我们采用经典岩石圈模型，分别在表面和莫霍面施加外部和内部载荷，并假设补偿物质比莫霍面的地幔物质密度大。岩石圈挠度误差主要来源于该岩石圈模型的T - e和Moho恢复误差。然后进行了综合建模，分析了T和Moho误差的影响。综合模型分析表明：(1)te误差引起的挠曲误差呈波纹状，且在高te区域波纹状较宽；(2) Moho误差引起的挠曲误差主要发生在低热区，在低热区应用Airy均衡理论仍可能大大高估岩石圈变形幅度；(3)岩石圈挠度误差在高、低温度区分别以T - e和Moho误差为主。
Lithospheric deformation is a fundamental process in plate tectonics. It is, therefore, critical to determine how the lithosphere responds to geological loads to better understand tectonic processes. The lithosphere can be modelled as the flexure of a thin, elastic plate over long-term (> 10 5 yr) geological timescales. The partial differential equation for the flexure of an orthotropic plate is used indirectly to calculate theoretical admittance and coherence, which are then compared against the observed admittance and coherence to invert for the non-uniform flexural rigidity (or effective elastic thickness, T e) of the plate. However, the process for accurately recovering variable lithospheric flexure remains unresolved, as the classical lithospheric model may overestimate the deflection of the plate. Here we adopt the classic lithospheric model with applied external and internal loads at the surface and Moho, respectively, and assume that the compensation material is denser than the mantle material beneath the Moho. The lithospheric flexure errors are derived mainly from the T e and Moho recovery errors in this lithospheric model. Synthetic modelling is then performed to analyse the influence of the T e and Moho errors. The analysis of synthetic modelling shows that:(1) the T e error-induced flexure errors exhibit a rippling pattern, and the rippling pattern is broader in high T e regions;(2) the Moho error-induced flexure errors mainly occur in the low T e regions, and applying Airy isostasy theory in low T e regions may still greatly overestimate the lithospheric deformation amplitude; and (3) the lithospheric flexure errors are dominated by the T e and Moho errors in the high and low T e regions, respectively.