图书馆知识库

Almost all the collisional orogens are constructed of accreted terranes, which are commonly regarded as an essential component. Previous studies have extensively investigated physical processes of terrane accretion as well as the corresponding geological records, but terrane deformation behaviors and the detachment modes due to continuous continental convergence are still poorly understood. In this work, we built a series of 2D numerical models involving two terranes representing multi-terrane structure of the natural orogens, to explore the effects of rheological properties and geometric parameters of the terrane on itself deformation and dynamic evolution of the collision zone. Model results reveal that the deformation behaviors of the terranes are mainly controlled by the rheological strength and the geometric width of the terrane that neighbors on the subduction zone, whereas the width of the farther terrane won't affect much. More importantly, according to the model results, intra-terrane underthrusting only occurs under the condition of a wide subduction-zone-neighboring terrane, and it is the weak terrane that usually underthrusts the relatively strong terrane. This study not only indicates two contrasting terrane deformation modes that might be applied to western and central Tibet, but also provides significant implications for lithospheric evolution of the natural orogens that contain a number of accreted terranes.