Abstract: The use of plasticized rosin as an analog material of the ductile lower lithosphere provides an effective approach to modelling intraplate plastic-flow network and multi-layer tectonic deformation. The experiments of ductile single-layer models indicate that under the action of compression at the plate boundary or gravity potential of "plateau" the first-order tectonic patterns,including those of shear network,compressional fold,or their transitional type,are observed respectively corresponding to the condition of relatively high,low,or moderate viscosities. In the ductile/brittle two-layer model with solidified talc-powder slurry as its britte upper layer the long-range transmission of driving force at the plate boundary is carried out mainly by netlike flow through the ductile lower layer,and,therefore,the shear network,i.e. plastic-flow network,in the lower lithosphere controls the intraplate tectonic deformation resulting in the development of shear fracture network,thrust faults,longitudinal tension fractures,and other secondary-order faults or folds in the brittle upper layer. The experiments also show that the discontinuously-distributed partings of weakness,which model low-velocity or high-conductivity layer in the crust,do not obstruct spreading of plastic-flow network in the lower layer,though influence the upward transmission of drag force and the distribution of intensity of tectonic deformation in the upper layer.

Key words: Lithosphere, Plastic deformation, Brittle deformation, Physical modelling, Plastic-flow network

摘要： 采用塑化松香作为岩石圈延性下层的相似材料,进行了板内塑性流动网络及多层构造变形的物理模拟实验。延性单层模型的实验表明,在边界挤压或“高原”重力势的作用下,依赖于延性层粘度的高低不同,主要形成剪切网络、压性褶皱以及二者过渡型式等一级构造。在延性/脆性双层模型中(脆性上层和延性下层分别相当于岩石圈上、下层),边界驱动力的远程传递,主要借助于延性下层的网络状流动,岩石圈下层(含下地壳和岩石圈地幔)的剪切网络,即塑性流动网络,控制着板内构造变形,导致脆性上层内剪切破裂网络、逆推断裂、纵向张裂以及其它次级断裂和褶皱的发育。实验还表明,上、下层之间非连续分布的软弱夹层(模拟壳内低速、高导层)并不妨碍下层塑性流动网络的扩展,但影响牵引力的向上传递及上层构造变形的强弱分布。

关键词: 岩石圈, 塑性变形, 脆性变形, 物理模拟, 塑性流动网络