Creep Rheology of Antigorite: Experiments at Subduction Zone Conditions
Creep Rheology of Antigorite: Experiments at Subduction Zone Conditions
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DOI：
10.1029/2022jb024260
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发表时间：
2022-07-01
影响因子：
3.9
通讯作者：
Hirth, Greg
中科院分区：
文献类型：
--
作者：
Burdette, Eric;Hirth, Greg
采用新型流体介质压力室，在低温、低应变率(10(-9)~10(-4)1/S)和高压(1 Gpa)的恒应力蠕变条件下，对斜方辉石进行了变形实验。安提戈特岩芯在75摄氏度至550摄氏度的恒定温度下变形，每个温度施加8-12个应力应变步骤。变形样品的微观结构与以前工作中记载的特征相同(如剪切微裂纹)，并突出了底部剪切和扭结对反花岗岩塑性的重要性。流变数据符合低温塑性定律，符合大晶格电阻的变形机制。当应用于地质应力和应变率时，外推的粘度与基于俯冲带热模型的预测非常一致。
Novel fluid medium pressure cells were used to deform antigorite under constant stress creep conditions at low temperature, low strain rate (10(-9) - 10(-4) 1/s), and high pressure (1 GPa) in a Griggs-type apparatus. Antigorite cores were deformed at constant temperatures between 75 degrees C and 550 degrees C, by applying 8-12 stress-strain steps per temperature. The microstructures of deformed samples share features documented in previous work (e.g., shear microcracks), and highlight the importance of basal shear and kinks to antigorite plasticity. Rheological data were fit with a low temperature plasticity law, consistent with a deformation mechanism involving large lattice resistance. When applied at geologic stresses and strain rates, the extrapolated viscosity agrees well with predictions based on subduction zone thermal models.