关键词: 克拉通, 地幔风, 数值模拟, 动态演化

Abstract:

Cratons typically possess a thick, low-heat-flow, and high-rheological-strength cratonic lithospheric mantle. Meanwhile, geophysical observations have identified clear vertical layering within the lithospheric mantle, attributed to modification by subducted slabs or deep mantle melts/fluids acting from below. However, although lateral mantle wind disturbances are known to play a crucial role in craton evolution, their impact on the vertical layering of cratonic lithospheric mantle and the underlying mechanisms remain unexplored. This study uses 2D thermodynamic numerical modeling to analyze the effects of mantle wind on model outcomes under various thermal and density structures of the cratonic lithosphere. The results reveal that lateral mantle wind disturbances create a low-viscosity zone between the upper and lower cratonic lithospheric mantle, and the lower lithospheric mantle, which is exposed to the asthenosphere, experiences horizontal displacement relative to the overlying plate. Rocks within the low-viscosity zone undergo significant dynamic metamorphism, leading to reduced permeability, which confines the modifying effects of melts/fluids below its lower boundary and thereby controls the formation of vertical layering in the cratonic lithosphere through metasomatism. This phenomenon may also serve as a self-protective mechanism for the cratonic lithosphere, where the accumulation of melts/fluids enriches weak-rheological-strength minerals such as phlogopite and amphibole in the low-viscosity zone, forming a weak layer within the cratonic lithosphere. Subsequently, the lithospheric mantle may delaminate along this weak layer under mantle wind or subducted slab influence, thus separating the overlying plate from the heavily modified lower cratonic lithospheric mantle.

Key words: craton')">

craton, mantle wind, numerical modelling,   ')">dynamic evolution