Seismic Investigation of Lithospheric Strain: The Red Sea Rift

杰弗里·帕克在红海地区，一个大陆盾已经断裂，形成了一个早期的海洋盆地。该区域大陆裂谷过程的几个阶段是明显的，从红海中部真正的洋壳形成到沿死海变换沿着的横向拉分运动。这种裂谷的表面特征已被很好地绘制出来，但其下地壳和地幔岩石圈中韧性剪切的范围和几何形状尚不清楚。随着宽带数字地震数据记录的出现，利用地震各向异性作为下地壳和上地幔变形的代用指标变得普遍。然而，只有一小部分的数据可从常设地震观测站在红海地区进行了探讨与技术，直接解决各向异性特性。调查人员将利用诊断弹性各向异性的地震观测资料-地震横波分裂和接收器功能，研究红海地区下地壳和浅地幔的结构和结构。这两种技术在很大程度上是互补的：横波分裂沿横波路径整合各向异性沿着，而P-S转换波是敏感的速度和各向异性跳跃界面。它们共同提供了一种方法来约束各向异性特性的垂直变化，这应该使我们能够区分继承岩石纹理内的元古宙时代岩石圈与纹理与正在进行的大陆分裂。

EAR-0208031Jeffrey J. ParkIn the Red Sea region, a continental shield has rifted to form an incipient ocean basin. Several stages of the continental rifting process are evident in the region, ranging from the formation of genuine oceanic crust in central Red Sea to transcurrent pull-apart motion along the Dead Sea transform. Surface features of this rifting are well mapped, but the extent and geometry of ductile shear in the underlying lower crust and mantle lithosphere are unknown. The use of seismic anisotropy as a proxy for the deformation of the lower crust and upper mantle became widespread with the advent of broadband digital seismic data recording. However, only a small subset of data available from permanent seismic observatories in the Red Sea region has been explored with techniques that address anisotropic properties directly. The investigators will study the structure and the texture of the lower crust and the shallow mantle in the Red Sea region using seismic observables that diagnose elastic anisotropy - teleseismic shear wave splitting and receiver functions. These two techniques are largely complementary: shear-wave splitting integrates anisotropy along the path of a shear wave, while P-S converted waves are sensitive to velocity and anisotropy jumps at interfaces. Together they offer a way to constrain vertical variations in anisotropic properties, which should allow us to distinguish inherited rock textures within the Proterozoic-age lithosphere from textures associated with the ongoing continental break-up.