Influence of continental roots and asthenosphere on plate-mantle coupling
Influence of continental roots and asthenosphere on plate-mantle coupling
复制标题
DOI：
10.1029/2005gl025621
复制
发表时间：
2006-03-15
影响因子：
5.2
通讯作者：
Lithgow-Bertelloni, C
中科院分区：
文献类型：
--
作者：
Conrad, CP;Lithgow-Bertelloni, C
地幔流对地球岩石圈底部施加的剪切牵引力形成板块驱动力和岩石圈应力。通过比较岩石圈和软流圈横向变化黏度的地幔流模型和层状黏度的地幔流模型计算的剪切黏度，研究了这些牵引力对亚岩石圈黏度变化的敏感性。横向粘度变化一般不会改变剪切牵引的方向，但与100 km厚的岩石圈相比，深穿透的大陆根使牵引强度增加了2-5倍。低粘度软流层对牵引力的影响较小，只有在100公里厚的情况下才有作用。在这些地区，厚大陆岩石圈下板块-地幔耦合的增加可能会增加板块驱动力、地表变形和地幔源岩石圈应力。相比之下，低粘度软流圈不会使岩石圈与地幔流分离，这突出了地幔牵引力对岩石圈的地质重要性。
The shear tractions that mantle flow exerts on the base of Earth's lithosphere contribute to plate-driving forces and lithospheric stresses. We investigate the sensitivity of these tractions to sub-lithospheric viscosity variations by comparing shear tractions computed from a mantle flow model featuring laterally-varying lithosphere and asthenosphere viscosity with those from a model with layered viscosity. Lateral viscosity variations generally do not change the direction of shear tractions, but deeply penetrating continental roots increase traction magnitudes by a factor of 2-5 compared to 100 km thick lithosphere. A low-viscosity asthenosphere decreases traction magnitudes by a smaller amount, and is important only if >100 km thick. Increased plate-mantle coupling beneath thick continental lithosphere may increase plate-driving forces, surface deformation, and mantle-derived lithospheric stresses in these regions. By contrast, a low-viscosity asthenosphere does not decouple the lithosphere from mantle flow, highlighting the geological importance of mantle tractions on the lithosphere.