剪切带中斑晶的运动学和变形分析及塑性大变形计算机模拟  

Analysis for Kinetics and Deformation of Porphyroblasts within Ductile Shear Zones and Numerical Modeling in Large Plastic Deformation

作　　者：梁海华[1] 刘树文[1] 孙晓松 阎志梅 

机构地区：[1]北京大学地质学系,北京100871

出　　处：《北京大学学报（自然科学版）》2000年第1期117-123,共7页Acta Scientiarum Naturalium Universitatis Pekinensis

基　　金：国家自然科学基金

摘　　要：在对太行山阜平地区三条剪切带作了详细观察和测量的基础上，就斑晶旋转和眼球构造进行了塑性大变形的计算机模拟。计算结果表明：刚性的石榴石斑晶会随着基质的流动而产生旋转运动，旋转量的大小取决于剪切力的大小、斑晶的密集度以及斑晶在剪切带中的位置。长石眼球构造的形成主要是由长石与石英的韧性差决定的，塑性变形首先从斑晶的周围部分开始，逐渐向斑晶发展，脆性残斑核不断减小，这与剪切带内糜棱岩化强度分带相一致。Numerical modeling for porphroblast's rotation and deformation of augen fabrics in ductile shear zones is done by a large plastic deformation programm based on detailed investigation to three ductile shear zones, Taihangshan Mountains. Some results acquired by computer calculation show that the rigid garnet pophyroblasts can rotate as their matrix flow, and the rotational degree depends on the shear force, ratio of poephroblasts to matrix and the locations of porphyroblasts in the model. Formation of augen fabrics is decided by the ductile deference between the porphyroblast and matrix in deformation rock. Plastic strain first starts from ambient of the porphyroblast, and then develops to rims of porphyroblast and gradually transfers to the centers of porphyroblasts. The brittle remains in the central parts of porphyroblasts come to be decreased through the plastic deformation development, which is accordance with the banding of intensity in many mylonitization zones on wild occurrences and observation in the fabrics of mylonitization rocks under microscope.

关 键 词：剪切带 斑晶 塑性大变形 计算机模拟 太行山 

分 类 号：P545[天文地球—构造地质学]