Collaborative Research: Seismological and Geodynamic Investigation of Mantle Anisotropy

本项目将评估上地幔方位各向异性的全球地震学和地球动力学模型的鲁棒性、分辨率和所需的复杂性，以提高我们对地幔动力学的理解。近年来，人们对地震各向异性模型进行了改进，这些模型可能表明了地幔流的剪切作用。特别是表面波反转已经成功地与地幔环流模型联系起来。这些发现使得在不久的将来使用复杂的合成数据集来测试区域构造模型的假设似乎是可行的。然而，虽然关于各向异性影响的几个问题仍未得到解答，但对不确定性进行彻底估计的全面和定量模型仍然缺乏，这也是事实。该项目解决了地震分析和改进地球动力学模型的一些相关问题，例如：相对于数据选择和反演方法，方位角各向异性模式有多稳定？大陆和海洋区域下各向异性的约束有多好？对流模型的特点是什么，从牛顿到幂律流变学，从横向恒定到变化粘度，从有限应变到纹理建模。将进行一系列分辨率和综合模型试验，以评估地震模型的稳健性。这样一个地震学和地球动力学相结合的研究项目将导致对上地幔结构、各向异性形成和地幔对流的新见解。目的是使我们对基于地幔流动的岩石圈和上地幔变形的理解形式化，以便开发具有特定区域预测的模型，这些模型对现场活动的设计和地质假设检验有用。

This project will evaluate the robustness, resolution, and required complexity of global seismologic and geodynamic models of upper mantle azimuthal anisotropy in order to improve our understanding of mantle dynamics. Recent years have seen a refinement of seismological models of anisotropy, presumably indicative of shearing in mantle flow. Particularly surface wave inversions have been linked to models of mantle circulation with some success. Such findings make it appear feasible to test hypotheses for regional tectonic models using sophisticated synthetic data sets in the near future. However, while several questions about the implications of anisotropy remain unanswered, it is also true that comprehensive and quantitative models with thorough estimates of uncertainties are still lacking. This project addresses some of the relevant issues of seismological analysis and improved geodynamic models, such as: How stable are azimuthal anisotropy patterns with respect to data selection and inversion methods? How well constrained is anisotropy under continents and oceanic regions? What are the characteristic to convection models, from Newtonian to power-law rheology, from laterally constant to varying viscosity, and from finite strain to texture modeling. A range of resolution and synthetic model tests will be performed to evaluate the robustness of the seismological models. Such a combined seismologic and geodynamic research program will lead to new insights into upper mantle structure, anisotropy formation, and mantle convection. The aim is to formalize our understanding of lithospheric and upper mantle deformation based on mantle flow, in order to develop models with specific regional predictions that are useful for the design of field campaigns and geologic hypothesis testing.