Department of Geological Sciences, Brown University, Providence, RI 02912, USA.
Science. 2011 Nov 11;334(6057):783-7. doi: 10.1126/science.1208898. Epub 2011 Oct 6.
The stretching and break-up of tectonic plates by rifting control the evolution of continents and oceans, but the processes by which lithosphere deforms and accommodates strain during rifting remain enigmatic. Using scattering of teleseismic shear waves beneath rifted zones and adjacent areas in Southern California, we resolve the lithosphere-asthenosphere boundary and lithospheric thickness variations to directly constrain this deformation. Substantial and laterally abrupt lithospheric thinning beneath rifted regions suggests efficient strain localization. In the Salton Trough, either the mantle lithosphere has experienced more thinning than the crust, or large volumes of new lithosphere have been created. Lack of a systematic offset between surface and deep lithospheric deformation rules out simple shear along throughgoing unidirectional shallow-dipping shear zones, but is consistent with symmetric extension of the lithosphere.
构造板块的拉伸和断裂控制着大陆和海洋的演化，但在断裂过程中岩石圈如何变形和适应应变仍然是个谜。利用南加利福尼亚裂谷带及其相邻地区的远地震横波散射，我们确定了岩石圈-软流圈边界和岩石圈厚度变化，以直接约束这种变形。裂谷区下方的岩石圈显著且横向急剧变薄，表明应变的有效局部化。在索尔顿槽，地幔岩石圈经历的变薄程度超过地壳，或者新岩石圈的体积较大。如果表面和深部岩石圈变形之间没有系统的偏移，则排除了沿贯通的单向浅层倾斜剪切带的简单剪切，但与岩石圈的对称伸展一致。
