关键词: 剪切带, 斑晶, Maxwell体, 有限元数值模拟, 太行山

Abstract: Numerical viscoelastic modeling for porphyroclast rotation in ductile shear zones is done by a viscoelastic finite element program based on detailed investigation to three ductile shear zones, the Taihangshan Mountains, North China. In this model porphyroclast (garnet) is assumed as isotropic elastic material with small elastic deformation, while the matrix (quartz, feldspar) as viscous fluid (Maxwell material) which has increasing deformation with time. The viscosity of matrix is supposed to be 10²⁰Pa·s, which is varied in alternating models to discuss the effect of visvosity on deformation because it is hard to estimate the true value of the crust. Some results acquired by computer calculation show that the rigid garnet porphyroclasts can rotate as the matrix flows, and the rotational degree depends on the shear stress, shear strain, ratio of porphroclasts to matrix and the locations of porphyroclasts in the zone.

Key words: shear zones, porphyroclast, Maxwell body, numerical modeling, Taihangshan Mountains