褶皱冲断带构造砂箱物理模型研究进展

A Review of Tectonic Sandbox Modeling of Fold-and-thrust Belt

地壳浅层次褶皱冲断带普遍受控于具耦合互馈特性的多种机制或边界条件,从而具有长期的构造演化过程和复杂的构造特征。自19世纪初以来,基于地质构造过程自相似性和"无理有效性"的砂箱物理模型,为解译褶皱冲断带的演化过程及其动力学机制等提供了独立有效的手段。本文主要基于国内外地壳浅表褶皱冲断带构造变形过程为研究对象的构造砂箱物理模型研究结果与进展进行综述性报道,以期为同行提供参考与借鉴。基于与地壳浅表地层具相似流变学特性的砂箱物理模拟研究,揭示出地壳浅层次构造变形过程普遍自相似性生长过程,符合库伦临界楔理论。褶皱冲断带挤压变形过程中,基底特性(基底几何学、有效摩擦角、基底耦合性和流体超压)、变形物质特性(空间几何学、能干层、流变学和非均一性)、动力学机制(砂箱几何边界、汇聚速率和汇聚方向)、浅表作用(剥蚀和沉降)等对于地壳浅表构造变形过程具有明显的控制作用。构造砂箱物理模型在解译不同构造变形过程与机制的研究中发挥着越来越突出的作用。

Brittle deformation in fold-and-thrust belt of shallow crust is generally characterized by a long tectonic history and complex geological features which results from interdependent parameters. Since the 1810 s, tectonic sandbox modeling has been a powerful and indispensable tool to help in providing a unified picture of the evolution of deformation in shallow crust with considerable spatial and temporal detail based on self-organization and unreasonable effectiveness of tectonics. Here we review current understandings from tectonic sandbox models of fold-and thrust belt, to help present and future modelers and researchers in understanding of basin-mountain evolution and their dynamics. The classic sandbox models suggest that extensional and shortening deformation in shallow crust follow the critical Coulomb wedge theory, with self-similar growth processes. Furthermore, past practices of sandbox modeling have explored the role of main parameters governing deformation, and these parameters are the properties of basement（geometry, friction, basal coupling, fluid overpressure）, the properties of deforming material（geometry, rheology, mechanical layering, inhomogeneity）, kinematics（boundary geometry, velocity, obliquity） and surface processes（erosion and sedimentation）. It should be noted that the sandbox models have grown increasingly bold in understanding mechanical and structural evolution of fold-and-thrust belt in shallow crust, and inconsistence between models and natural systems are common in parameters such as spatial scale, time scale, material properties, and number of active processes.