Magmatic underplating of crust beneath the Laccadive Island, NW Indian Ocean

Abstract

We investigate the crust and uppermost mantle velocity structure beneath the Laccadive Island through the inversion of teleseismic receiver functions following the neighbourhood algorithm. The velocity structure suggests that the 16-km thick-oceanic crust is underplated by 8-km thick high-velocity layer (Vs~4.25-4.4 km s; Vp~7.35-7.6 km s). The uppermost mantle shear velocity is ~4.6 km s (Vp~8.18 km s. The Moho at 24 km is possibly formed due to underplating of mantle-derived picritic melt at the base of oceanic crust produced during the interaction of the Indian plate with the Reunion hotspot. Continuity of crustal-underplated material beneath the Laccadive could be traced to the Laxmi Ridge in the north and to the Reunion Island in the south, suggesting this to be possible trace of the Reunion hotspot.