Abstract: Rheological parameters and deformation mechanisms of rocks are the basis for estimating crustal strength by using frictional constitutive equations and power law creep equations. In the past 30 years, substantial progress has been made in high-temperature and high-pressure experimental studies, which provide a large numbers of data on rheological parameters of crustal minerals and rocks, as well as new insights into the deformation mechanisms. In this paper, we summarize systematically the existing experimental data, and study crustal rheology of North China by using these data combined with focal depth distributions in this region. The results show that the upper crust as represented by granite and low-grade metamorphic rocks is deformed in brittle faulting and frictional sliding regime, the strength of which is controlled by friction on faults; the middle crust comprising felsic-gneiss, as well as the upper layer of lower crust composed of intermediate granulite behave in plastic flow regime; the lower layer of lower crust consists of dry mafic granulite, which behaves in brittle-plastic flow transition regime. The composition and rheological stratification of the crust in North China may cause decoupling of different crustal layers and provide mechanical conditions for strong earthquake generation. In addition, they may also serve as the bottom boundaries for blocks of different scales.

Key words: crustal rheology, rheological parameter, deformation mechanism, North China

摘要： 岩石流变参数和变形机制是根据断层摩擦和岩石幂次流动本构关系建立岩石圈强度剖面的基础.近30年来,高温高压实验取得了很大进展,获得了大量地壳矿物和岩石流变资料.本文系统总结了这些流变实验资料,并应用流变数据结合地震震源深度分布,对华北地壳流变性质进行了研究.结果表明,以花岗岩和低级变质岩为代表的上地壳为脆性破裂,其强度受断层摩擦约束,以长英质片麻岩为主的中地壳和以中性麻粒岩为主的下地壳上层处于塑性流变状态,由干的基性麻粒岩组成的下地壳下层处于脆性向塑性流变的过渡状态.华北地壳的这种物质组成和流变为地壳不同层次的解耦和强震孕育提供了力学条件,也构成了不同尺度块体的底边界.

关键词: 地壳流变, 流变参数, 变形机制, 华北