东太平洋海隆MELT区域下方的剪切波分裂及其对地幔流动的意义。

Shear-wave splitting and implications for mantle flow beneath the MELT region of the east pacific rise.

作者信息

Wolfe CJ, Solomon SC

机构信息

C. J. Wolfe, Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA. S. C. Solomon, Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, DC 20015, USA.

出版信息

Science. 1998 May 22;280(5367):1230-2. doi: 10.1126/science.280.5367.1230.

DOI:10.1126/science.280.5367.1230

PMID:9596569

Abstract

Shear-wave splitting across the fast-spreading East Pacific Rise has been measured from records of SKS and SKKS phases on the ocean-bottom seismometers of the Mantle Electromagnetic and Tomography (MELT) Experiment. The direction of fast shear-wave polarization is aligned parallel to the spreading direction. Delay times between fast and slow shear waves are asymmetric across the rise, and off-axis values on the Pacific Plate are twice those on the Nazca Plate. Splitting on the Pacific Plate may reflect anisotropy associated with spreading-induced flow above a depth of about 100 km, as well as a deeper contribution from warm asthenospheric return flow from the Pacific Superswell region.

摘要

利用地幔电磁与层析成像（MELT）实验中海底地震仪记录的SKS和SKKS震相，对快速扩张的东太平洋海隆上的剪切波分裂进行了测量。快剪切波偏振方向与扩张方向平行。快、慢剪切波之间的延迟时间在海隆两侧不对称，太平洋板块上的离轴值是纳斯卡板块上的两倍。太平洋板块上的分裂可能反映了与大约100公里深度以上的扩张诱导流相关的各向异性，以及来自太平洋超级地幔柱区域的温暖软流圈回流的更深层次贡献。