Abstract Serpentinization of the mantle wedge immediately above a subducting slab is a key process controlling the strength contrast between the slab and the overriding nominally anhydrous (i.e., olivine-rich) mantle. To assess the influence of serpentinite rheology on the degree of decoupling between the slab and mantle wedge, we conducted axial compression tests on partially foliated antigorite serpentinite using a modified Griggs-type apparatus at confining pressures (Pc) of 1.0–2.5 GPa, temperatures (T) of 300–600 °C, and a strain rate of 1.5 × 10−5 s−1. With increasing temperature, the dependence of maximum differential stress (i.e., strength) on Pc changes from positive to flat, suggesting an increasingly important contribution from plastic deformation. Microstructural observations show that increasing temperature promotes a transition in deformation mechanisms from distributed inter- and intra-granular microcracking to comminution and kinking localized within a through-going shear zone. The ductile-to-brittle transition can be attributed to the operation of thermally activated processes such as dislocation glide and grain boundary sliding in aligned antigorite grains. Comparison with strength data for dunite demonstrates that in the semi-brittle regime, the strength contrast between antigorite and olivine is

中文翻译：

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弧前地幔楔条件下叶蛇纹石蛇纹岩的半脆性变形

摘要 俯冲板片正上方地幔楔的蛇纹石化是控制板片与上覆名义上无水（即富含橄榄石）地幔之间强度对比的关键过程。为了评估蛇纹岩流变学对板片和地幔楔之间解耦程度的影响，我们使用改进的 Griggs 型装置在 1.0-2.5 GPa 的围压 (Pc)、温度 ( T) 为 300–600 °C，应变率为 1.5 × 10−5 s−1。随着温度升高，最大微分应力（即强度）对 Pc 的依赖性从正变为平坦，表明塑性变形的贡献越来越重要。微观结构观察表明，升高的温度促进了变形机制从分布的晶间和晶内微裂纹转变为位于贯穿剪切带内的粉碎和扭结。韧脆转变可归因于热激活过程的操作，例如排列的叶蛇纹石晶粒中的位错滑移和晶界滑移。与单晶的强度数据对比表明，在半脆性状态下，叶蛇纹石和橄榄石的强度对比为 韧脆转变可归因于热激活过程的操作，例如排列的叶蛇纹石晶粒中的位错滑移和晶界滑移。与单晶的强度数据对比表明，在半脆性状态下，叶蛇纹石和橄榄石的强度对比为 韧脆转变可归因于热激活过程的操作，例如排列的叶蛇纹石晶粒中的位错滑移和晶界滑移。与单晶的强度数据对比表明，在半脆性状态下，叶蛇纹石和橄榄石的强度对比为