岩石圈的流变性与大陆动力学的科学基础

地球是一动态系统,其各层圈的构造运动归根究底就是多矿物复合岩石及其中各主要造岩矿物在变化的物理条件(例如,温度、围压、差应力、应变速率、应变方式等)下和化学环境(例如,氧逸度和水含量)中的形变。岩石流变学是一门研究岩石力学性质和变形行为的科学,现已成为定量大陆动力学和构造地质学发展的一个瓶颈,超越这个瓶颈,学科才能大踏步前进。本文对过去四十年来岩石流变学的实验和韧性变形域内古应力研究成果做了简明扼要的总结,特别关注尚存的问题与急需克服的困难。强调运用现代材料学、地球物理学和地球化学的新理论和新方法,改进与完善高温高压实验设备,提高其力学测量的灵敏度和准确度。而且必须采用大应变的实验途径解决稳态蠕变与稳态显微构造的问题,保证实验所获流动律外延至自然界的合理性与稳定性。鼓励那些有坚实积累、开阔视野和科学思维的青年学者,开拓进取,在岩石圈流变学与大陆动力学领域做出经得起时间淘洗、实践检验的原创性成果来。

Dislocation creep and flow strength of the Earth 's crust

In this paper,we provide an up-to-date comprehensive compilation of dislocation creep and the rheological properties of crustal minerals and polymineralic rocks.We also review the current status of paleostress estimates based on free dislocation density,subgrain and recrystallized grain sizes,and microboudinage.There are large discrepancies between the published results of experimental deformation on the same mineral or rock,making a reliable extrapolation of the experimentally determined flow laws to natural strain rates difficult.The main causes of the discrepancies are:(1)non-achievement of steady-state creep or steady-state microstructures(e.g.,grain size,dislocation density,and texture);(2)incomplete characterization of water content;and(3)imprecise measurements of differential stress.Resolving these issues will improve our quantitative studies of the lithospheric materials and deformation mechanisms.This paper also encourages young geoscientists to engage in challenging research to advance our understanding of continental tectonics and geodynamics through detailed and comprehensive studies of the rheology of continental crust and mantle rocks.