High-pressure creep of serpentine, interseismic deformation, and initiation of subduction
High-pressure creep of serpentine, interseismic deformation, and initiation of subduction
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DOI：
10.1126/science.1148494
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发表时间：
2007-12-21
期刊：
影响因子：
56.9
通讯作者：
Petitgirard, Sylvain
中科院分区：
文献类型：
--
作者：
Hilairet, Nadege;Reynard, Bruno;Petitgirard, Sylvain
假定的低粘度的蛇纹岩可能会强烈影响俯冲带的动力学在所有的时间尺度，但直到现在它的作用无法量化，因为测量有关的中间深度设置缺乏。在高压和高温（1至4千帕，200至500摄氏度）下对蛇纹石叶蛇纹石的变形实验表明，蛇纹石的粘度远低于主要的地幔形成矿物。无论温度如何，板片表面的低粘度蛇纹状地幔都可以使变形局部化，阻止应力积累，并限制俯冲带大地震的下倾传播。叶蛇纹石使粘性松弛的特征时间与大地震和慢地震后的长期震后变形相当。叶蛇纹石的粘度低到足以使大洋岩石圈中的蛇纹化断层成为俯冲作用的起始点。
The supposed low viscosity of serpentine may strongly influence subduction- zone dynamics at all time scales, but until now its role could not be quantified because measurements relevant to intermediate- depth settings were lacking. Deformation experiments on the serpentine antigorite at high pressures and temperatures ( 1 to 4 gigapascals, 200 degrees to 500 degrees C) showed that the viscosity of serpentine is much lower than that of the major mantle- forming minerals. Regardless of the temperature, low- viscosity serpentinized mantle at the slab surface can localize deformation, impede stress buildup, and limit the downdip propagation of large earthquakes at subduction zones. Antigorite enables viscous relaxation with characteristic times comparable to those of long- term postseismic deformations after large earthquakes and slow earthquakes. Antigorite viscosity is sufficiently low to make serpentinized faults in the oceanic lithosphere a site for subduction initiation.