Subduction zone rheology

• Published in: Physics of the earth and planetary interiors Vol. 127; no. 1; pp. 67 - 81
• Main Authors: Weidner, Donald J, Chen, Jiuhua, Xu, Yaqin, Wu, Yujun, Vaughan, Michael T, Li, Li
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.2001
• Subjects: Deep earthquakes; Majorite; Mantle minerals; Olivine; Perovskite; Rheology; Ringwoodite; Strength; Stress measurements; Subduction zone; Synchrotron; Wadsleyite; Deep earthquakes; Olivine; Ringwoodite; Perovskite; Rheology; Stress measurements; Mantle minerals; Subduction zone; Wadsleyite; Majorite; Synchrotron; Strength
• ISSN: 0031-9201; 1872-7395
• DOI: 10.1016/S0031-9201(01)00222-9

Rheological flow laws can be obtained from studies using multi-anvil high-pressure systems with synchrotron-based piezometers and strain metrics. The high flux X-ray source provides minute-scale time resolution with accurate measurement of diffraction patterns and direct sample images. Measurements of length changes with an accuracy of one part in 10 4 are being developed and will provide a new generation of rheological tools. Flow laws derived from peak broadening agree well with literature data for corundum, spinel, and olivine. Properties of several mantle phases are compared for the temperature and pressure regime appropriate to a subducting slab. Temperature dependence of these properties exhibits a strong, temperature insensitive low temperature region, a thermally softened region and a weak high temperature region. The middle of these could be related to the seismogenic zone of a subduction zone. The progression of the temperature for softening with mineral phase suggests that earthquakes deeper than 400 km correspond to higher temperatures than for olivine in the upper 400 km. Plastic instabilities are suggested by these data as the origin of deep earthquakes.