Abstract: In this paper,we summarized deformation mechanisms of crustal rocks and the progress of the rheological experiments under high temperature and pressure,and discussed the quality of rheological experiment data. Although a great amount of creep test data have been published,the data of natural felsic rock,as well as data of quartz published in early time are hard to be reduplicated. However, the creep data of quartz and feldspar published in recent years are of very high quality. Some studies show that flow laws of two-phase rocks could be fitted using the empirical and theoretical models and rheological parameters of end member minerals. However,the flow laws for felsic rocks are hard to be determined because of complicated components and special rheological properties. As a result,when rheological parameters of felsic rocks are used to estimate the strength profile of the continental crust,the stress envelope and the depth of brittle-plastic transition zone are different even in the same temperature and strain rate condition. Therefore,we suggest more creep experiments should be done in order to obtain high quality rheological data of felsic rocks.
Based on recent progresses in rheological experiment,the influence factors on rheology of felsic rocks in laboratory conditions are discussed,especially,the covering water,mineral component,grain size and fabric of the rock. Little water in the rock would have a significant weakening role on the rheological strength. The effect of the rheological strength of melt is dependent on the observations and the distribution of the melt. If grain boundaries are wetted by melt films,the weakening effect of the melt will become more obvious. The effect of mineral component on rock rheology is reflected not only by stress exponents of samples,but also transition temperature from semi-brittle state to plastic state. The grain size mainly influences the deformation mechanism of rocks. In diffusion regime,the flow stress has negative linear correlation with grain size of fine grain samples,which is not only used to estimate as stress piezometer,but also suitable to determine the rheological strength in the ductile shear zone. However,in dislocation regime,the flow stress is independent of grain size,which is the foundation in estimating the rheological strength of the crust rocks in natural condition using experimental data. Finally,the effect of rock fabric and anisotropy,which is the common phenomenon in the crust,on rheology of experimental samples is very limited,which needs further experimental studies to get more data.

Key words: rheology, deformation mechanism, felsic rocks, influence factors

摘要： 在总结岩石变形机制与岩石流变学实验进展的基础上,讨论了岩石流变学数据的重复性。虽然高温高压流变学实验积累了大量的数据,但中、上地壳长英质岩石和早期获得的石英集合体的流变实验数据重复性比较差,而近年来发表的石英、长石的流变学实验数据重复性相对较好。虽然利用经验理论模型,根据端元组分可以拟合两相矿物集合体的流变律,但并不能满足定量确定复杂组分和特殊流变性的长英质岩石流变参数的需要。因此,利用长英质岩石流变参数估计大陆地壳流变强度剖面时,即使在相同地温和应变速率条件下,给出的流变曲线、脆-塑性转化带深度也有一定差别,还需要通过大量实验给出更精细的长英质岩石流变学实验数据。根据近年来流变学实验研究的新进展,讨论了在实验室条件下影响长英质岩石流变的各种因素,重点分析了流体、岩石成分、样品粒度和组构对流变的影响。微量结构水对岩石流变有显著的弱化作用,而熔体对流变的影响与熔体含量和分布相关,只有熔体呈薄膜状湿润颗粒边界时,熔体的弱化作用才显著。成分对岩石流变的影响不仅体现在样品的应力指数等流变参数的变化方面,还体现在样品从半脆性变形向塑性变形的转化温度方面。粒度主要影响岩石的变形机制,其中,细粒样品在扩散蠕变域具有应力与粒度线性负相关特性,是理想的应力计,可以用来定量确定韧性剪切带的流变强度; 而在位错蠕变域,应力与粒度没有依存关系,这为将实验室条件得出的流变数据外推估计地壳流变提供了重要依据。组构和各向异性是地壳中岩石存在的普遍现象,但关于层状组构对多相矿物组成的岩石流变影响的研究非常少,需要通过新的实验来深入研究。

关键词: 流变, 变形机制, 长英质岩石, 影响因素