PHYSICAL EXPERIMENTS ON CONTINENT EXTENSIONAL STRUCTURES

According to the theory that plastic flow of the lower layer (including lower crust and upper mantle lithosphere) controls upper layer (upper crust) deformation in the multi-layer lithosphere, the paper studies the physical experiments of extensional structures adopted ductile/brittle double-layers model. The experiment results show that the lower ductile layer whose flow speed is larger than that of upper brittle layer. Controlled by compressed and free flow, the areas of model deformation can be divided into three parts:extensional region, transition region and compressive region. Among all, the main part is extensional region where "graben-horst" is characterized by major extensional structures. The displacements of mark points on upper face of models show that the deformation quantities of upper brittle layer are focus on the parts of faults. In addition, the passive uplifting of lower ductile layer is found at faults region of upper brittle layer in our models.