关键词: 岩石圈, 塑性变形, 脆性变形, 物理模拟, 塑性流动网络

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