论文标题
上地幔的橄榄石控制后震后蠕变中的脱位相互作用
Dislocation interactions in olivine control postseismic creep of the upper mantle
论文作者
论文摘要
施加在地幔岩石上的应力变化，例如地震施加的岩石岩石会引起粘度和微观结构的演变时期。这种瞬态蠕变通常是根据晶粒相互作用引起的滑动系统之间的应力转移来建模的。但是，最近的实验表明，位错之间应力的内部应力积累是在低温下橄榄石应变硬化的主要原因，这提出了一个问题，即同一过程是否有助于在较高温度下瞬时蠕变。在这里，我们证明了在25°C或1150至1250°C下变形的橄榄石样品都包含〜1 GPA的应力异质性，这些含量由位错构成，相关长度约为1微米。两种温度状态中形成的相似应力分布表明，位错之间应力的积累也为高温下的瞬态蠕变做出了贡献。结果激发了新一代模型，这些模型捕获了这些内部过程，并可能会在地震循环中对地幔粘度不断发展的预测进行改进。
Changes in stress applied to mantle rocks, such as those imposed by earthquakes, induce a period of evolution in viscosity and microstructure. This transient creep is often modelled based on stress transfer among slip systems due to grain interactions. However, recent experiments have demonstrated that the intragranular accumulation of stresses among dislocations is the dominant cause of strain hardening in olivine at low temperatures, raising the question of whether the same process contributes to transient creep at higher temperatures. Here, we demonstrate that olivine samples deformed at 25°C or 1150 to 1250°C both contain stress heterogeneities of ~1 GPa that are imparted by dislocations and have correlation lengths of ~1 micrometre. The similar stress distributions formed in both temperature regimes indicate that accumulation of stresses among dislocations also provides a contribution to transient creep at high temperatures. The results motivate a new generation of models that capture these intragranular processes and may refine predictions of evolving mantle viscosity over the earthquake cycle.
