Weak serpentine minerals affect the mechanical behavior of serpentinized peridotites at depth, and may play a significant role in deformation localization within subduction zones, at local or regional scale. Mixtures of olivine with 5, 10, 20 and 50 vol. % fraction of antigorite, proxies for serpentinized peridotites, were deformed in axial shortening geometry under high pressures (ca. 2–5 GPa) and moderate temperatures (ca. 350°C), with in situ stress and strain measurements using synchrotron X-rays. We evaluate the average partitioning of stresses at the grains scale within each phase (mineral) of the aggregate and compare with pure olivine aggregates in the same conditions. The in situ stress balance is different between low antigorite contents up to 10 vol. %, and higher contents above 20 vol. %. Microstructure and stress levels suggest the deformation mechanisms under these experimental conditions are akin to (semi)brittle and frictional processes. Unlike when close to dehydration temperatures, hardening of the aggregate is observed at low serpentine fractions, due to an increase in local stress concentrations. Below and above the 10–20 vol. % threshold, the stress state in the aggregate corresponds to friction laws already measured for pure olivine aggregates and pure antigorite aggregates respectively. As expected, the behavior of the two-phase aggregate does not evolve as calculated from simple iso-stress or iso-strain bounds, and calls for more advanced physical models of two-phase mixtures.

中文翻译：

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俯冲带压力下变形的合成蛇纹石化橄榄岩中的应力平衡

弱蛇纹石矿物影响蛇纹石化橄榄岩深部的力学行为，并且可能在局部或区域尺度的俯冲带变形局部化中发挥重要作用。橄榄石与 5、10、20 和 50 vol 的混合物。叶蛇纹石（蛇纹石化橄榄岩的代表）的百分比，在高压（约 2-5 GPa）和中等温度（约 350°C）下以轴向缩短的几何形状变形，并使用同步加速器 X 射线进行原位应力和应变测量。我们评估了骨料各相（矿物）内颗粒尺度上应力的平均分配，并与相同条件下的纯橄榄石骨料进行了比较。叶蛇纹石含量低至 10 vol. 之间，原地应力平衡是不同的。%，且含量高于 20vol. %。微观结构和应力水平表明这些实验条件下的变形机制类似于（半）脆性和摩擦过程。与接近脱水温度时不同，由于局部应力集中的增加，在低蛇纹石分数下观察到骨料的硬化。低于和高于 10-20 卷。％阈值，骨料中的应力状态分别对应于已经测量的纯橄榄石骨料和纯叶蛇纹石骨料的摩擦定律。正如预期的那样，两相聚集体的行为不会按照简单的等应力或等应变边界计算得出，并且需要更先进的两相混合物物理模型。