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Evidence for lowermost mantle anisotropy from discrepant splitting intensity of XKS and SKKS phases recorded in India.

Roy SK, Kumar MR.

PHYSICS OF THE EARTH AND PLANETARY INTERIORS

https://doi.org/10.1016/j.pepi.2025.107439 

The examination of shear wave splitting measurements of XKS (SKS and PKS) - SKKS pairs suggest for D˝ anisotropy beneath Southeast Asia and the Indian Ocean, which seems to be associated with paleo-subducted slabs. Further they suggest the observed deformation is due to phase transformation of bridgmanite to a more stable post-perovskite, causing Crystallographic Preferred Orientation of the lowermost mantle beneath Southeast Asia and the Indian Ocean.

Fig: The orientation and length of magenta lines indicate the fast polarization azimuth and strength of D˝ anisotropy, respectively plotted at a depth of 2700 km.

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