For progressively deforming multi-phase aggregates, it is unclear to what extent the change in geometry and orientation of the involved phases leads to textural strain weakening and thus may control strain localization. Consequently, the question arises how the ductile flow of multi-phase rocks can be described or determined. To contribute to the understanding of these knowledge gaps, two-dimensional numerical shear experiments of quartz-biotite aggregates were conducted at variable conditions. Textural variations after a shear strain of γ ≈ 10 appear to be dependent on the viscosity contrast between the minerals involved. To estimate whether a numerical experiment is undergoing strain weakening or hardening, the temporal evolution of the mean second invariant of the deviatoric stress tensor was tracked. The results suggest that strain weakening occurs if biotite is distinctly isolated in form of strong or weak inclusions and that it is more effective under conditions with larger viscosity contrasts between matrix and inclusions. However, observed stress drops in experiments purely based on textural strain weakening are low compared to other strain weakening processes. Numerical results from experiments with variable strain rate, temperature and biotite content were combined to determine two-phase flow law parameters for quartz-biotite aggregates, which are in broad agreement with existing analytical mixed-aggregate flow laws.

对于逐渐变形的多相聚集体，尚不清楚相关相的几何形状和取向的变化在多大程度上导致纹理应变减弱，从而可能控制应变局部化。因此，问题出现了如何描述或确定多相岩石的韧性流动。为了有助于理解这些知识差距，在可变条件下进行了石英-黑云母聚集体的二维数值剪切实验。γ剪切应变后的纹理变化 ≈ 10 似乎取决于所涉及的矿物之间的粘度对比。为了估计数值实验是否正在经历应变减弱或硬化，跟踪了偏应力张量的平均第二不变量的时间演变。结果表明，如果黑云母以强或弱包裹体的形式明显分离，则应变减弱发生，并且在基质和包裹体之间具有较大粘度对比的条件下更有效。然而，与其他应变弱化过程相比，在纯粹基于纹理应变弱化的实验中观察到的应力下降较低。结合具有可变应变率、温度和黑云母含量的实验的数值结果来确定石英-黑云母聚集体的两相流动规律参数，