Multi-scale rheology and strain localization of the continental lithosphere

岩石的力学流动特性(即岩石流变性)控制着岩石的变形，因此对于对板块构造、造山、地震和构造矿物、石油和天然气矿床的总体理解至关重要。然而，尽管这些尺度对经济和环境地质学具有最高的相关性，但人们对dm到10公里尺度的流变学知之甚少。该项目旨在通过一种创新的实验方法来填补这一空白，该方法将实验室变形实验和地质现场数据与热-机械多尺度数值实验相结合。在中等尺度上存在岩石流变学的基本不确定性，因为对流变学的限制主要来自毫米到厘米尺度的实验室变形实验或大规模地球物理和大地测量观测(10-100公里尺度)的反演。两者都不容易外推到中等长度尺度，因为流变学是依赖于尺度的，在地质时间和长度尺度上具有高度的动态性。这个问题的物理复杂性不允许理论上的解决方案。因此，提出了一种新颖的数值方法，该方法采用了一种新的热力学一致性多尺度方法，并利用实验室和自然数据进行了校准。本工程的主要成果有三：1)获得了从dm到km尺度的岩体流动规律。2)将小尺度实验室实验与大尺度地球物理和大地测量学相结合，确定了描述岩石流变学随尺度演化的定量规律。3)确定了地质条件下控制剪切局部化的物理尺度长度。

Mechanical flow properties (i.e., rock rheologies) control the deformation of rocks and are therefore of utmost importance for the general understanding of plate tectonics, mountain building, earthquakes, and structural mineral, oil, and gas deposits. However, little is known about rheology on dm- to 10km scales although these scales are of highest relevance for economic and environmental geology. This project intends to fill this gap with an innovative experimental approach that reconciles laboratory deformation experiments and geological field data with thermal-mechanical multi-scale numerical experiments. The fundamental uncertainty regarding rock rheology on intermediate scales exists because constraints for rheology mainly stem from mm- to cm-scale laboratory deformation experiments or from the inversion of large-scale geophysical and geodetic observations (10-100km scale). Both cannot be easily extrapolated to intermediate length scales because rheology is scale-dependent and highly dynamic over geological time and length scales. The physical complexity of this problem does not permit theoretical solutions. Therefore, an innovative numerical approach calibrated with laboratory and natural data is proposed that employs a new thermodynamically consistent multi-scaling method. Three main outcomes are expected from this project: 1) Flow laws of rock masses are obtained from dm- to km scale. 2) Quantitative laws describing how rock rheology evolves with scale are determined, connecting small-scale laboratory experiments with largescale geophysics and geodetics. 3) The physical scaling lengths governing shear localization on dm- to km scales under geological conditions are identified.