中国大陆岩石圈等效粘滞系数的计算和讨论

Effective viscosity of China continental lithosphere.

大陆岩石圈的流变结构对岩石圈动力学过程有很大的影响，因此对岩石圈等效粘度的估计是大陆动力学研究中基础和重要的问题。文中对利用实验室流变实验结果估算岩石圈流变结构的计算方法中包含的多种不确定性进行了讨论，包括岩性、温度、应变速率、实验室速率数据外推到地质构造运动速率等因素对等效粘滞系数估算的影响，并以温度和应变速率的新研究成果为基础，对中国大陆地壳和上地幔等效粘滞系数做出了估计。中国中地壳等效粘滞系数一般在10^21～10^24Pa·s，下地壳等效粘滞系数在10^21～10^22Pa·s，其中青藏高原下地壳等效粘滞系数较低，约为10^19～10^20Pa·s；与前人研究认为青藏高原存在柔性下地壳流动的结论吻合。

The rheological structure of continental lithosphere is a very important issue in the study of the lithospheric dynamics. The evaluation of lithospheric viscosity is a basic task. Based on the newly research achievements of China continental temperature and strain rate, we extrapolate the results of laboratory rock experi- ments to the field geological deformation, and carefully investigate the uncertainties in the calculation of lithospheric rheological structure, such as lithology, temperature, strain rate, and extrapolation effect. The effective viscosity of China continental crust and upper mantle are calculated. The effective viscosity of the middle and lower crust usually range from 10^21 to 10^24 Pa · s and from 10^21 to 10^22 Pa · s, respectively. The lower crust of the Tibetan plateau has a low viscosity of 1019-1020 Pa · s, which is consistent with the previous conclusion that there are ductile lower crustal flows in the Tibetan plateau.