Low-Frequency Attenuation in Polycrystalline Silicates and Silicate Partial Melts

Reid F.库珀，首席研究员威斯康星大学麦迪逊分校 将继续测量多晶橄榄石聚集体、橄榄石斜方辉石聚集体和橄榄石基部分熔体的低频衰减行为。 具体地，具有精心设计的微结构的多晶材料将经受动态（“亚共振”，振荡负载）和准静态（恒定负载，即，蠕变），以评估衰减行为作为（i）温度（1150至1350 ℃）、（ii）频率（2 × 10 e-4至1Hz）、（iii）相体积分数和形态（固态下的相渗透和相分离/分层;部分熔体中超过晶粒尺度的熔体偏析）和（iv）位错-蠕变亚显微结构的函数。 对地震频率吸收的微观结构效应（设计到这些样本中以模拟变形诱导的微观结构）的研究/表征是应用地震数据推断活动构造岩中变形行为的关键之一。

Reid F. Cooper, Principal InvestigatorUniversity of Wisconsin-Madison The measurement of the low-frequency attenuation behavior of polycrystalline olivine aggregates, of olivine-orthopyroxene aggregates and of olivine-based partial melts will be pursued. Specifically, the polycrystalline materials, which will have carefully engineered microstructures, will be subjected to dynamic ("sub-resonant", oscillatory loading) and quasistatic (constant loading, i.e., creep) so as to evaluate the attenuation behavior as functions of (i) temperature (1150 to 1350 degC), (ii) frequency (2x10e-4 to 1 Hz), (iii) phase volume fraction and morphology (phase percolation and phase separation/layering in the solid state; melt segregation beyond the grain scale in partial melts), and (iv) dislocation-creep sub-microstructure. The study/characterization of microstructural effects (engineered into these specimens so as to mimic deformation-induced microstructures) on seismic-frequency absorption is one key to applying seismic data to infer deformation behavior in active tectonic terranes.