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Upper mantle anisotropy from teleseismic SKS splitting beneath Lützow-Holm Bay Region, East Antarctica

Y. Usui·M. Kanao·A. Kubo·Y. Hiramatsu·H. Negishi
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Abstract

Investigations of SKS wave splitting of teleseismic events from digital seismographs recorded at eight stations around the Lützow-Holm Bay Region have lead to understanding the evolution of the Antarctic Plate. The observed delay times of SKS splitting are up to 1.3 s, which are generally equal to the global average. A two-layer model reveals that the lower layer anisotropy is caused by the recent asthenospheric flow, as compared with the Absolute Plate Motion by the HS3-NUVEL1 model. The upper layer anisotropy corresponds well to polarization of NE–SW convergence direction between East and West Gondwana in Pan-African age. We suggest that the upper layer anisotropy was formed during Pan-African orogeny and was possibly influenced by the preexisting structure during Gondwana break-up. The origin of anisotropy is the Lattice Preferred Orientation of olivine which was caused by both paleo-tectonic events and the recent asthenospheric flow.

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Y. Usui, M. Kanao, A. Kubo, Y. Hiramatsu, H. Negishi. 2007. Upper mantle anisotropy from teleseismic SKS splitting beneath Lützow-Holm Bay Region, East Antarctica. https://doi.org/10.3133/ofr20071047srp013

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