Upper-mantle anisotropy beneath the south Indian Shield: Influenced by ancient and recent Earth processes

摘要: ABSTRACT We obtained shear-wave splitting parameters from core-refracted phases like SKS, SKKS, and PKS at 75 digital broadband seismic stations almost uniformly spread over the south Indian Shield representing varied geological terrains, including western Dharwar craton, eastern Southern granulite terrain, continental margins along west east coasts. A majority of sta-tions craton show delay times 1–1.6 s, indicative a 150–200-km-thick anisotropic layer correlating with lithospheric root, while segments Pan-African terrain have 0.5–0.7 suggesting an internally deformed thin layer, possibly due to recent plate-tectonic geodynamic processes. The average direction anisotropy is generally ~N30°E, present-day plate motion, local deviations where correlates orienta-tion regional shear zones. Stations close margin large time delays (up 2 s) fast axis parallel rift axis. Further, we infer layered lithosphere in as revealed 90° periodicity two (fast time). upper represents depleted Archean mantle, lower could be transformed more fertile mantle subsequent deformation. This study suggests that observed result complex interplay between architecture its deformation different domains deep Earth