Thinning of the Indian craton due to the Reunion plume eruption

Since ~120 Ma, the Indian plate had interacted with at least three mantle plumes, namely, Kerguelen (~120 Ma), Marion (~90 Ma), and Reunion (~65 Ma). All these plumes have significantly affected the dynamics of the Indian plate. The unit of Indian craton has also been thought to be thinned down by these plume activities. It has been hypothesized that the eruption of the most recent one, i.e., the Reunion plume, has caused significant thinning of the Indian craton. In this work, we test this hypothesis using 3-D spherical time-dependent mantle convection models to investigate if the Reunion plume could have thinned down the Indian craton. At first, we reconstruct the location of the Indian craton till 65 Ma and insert a plume at the Reunion hotspot location. We have used reconstructed plate velocities to drive mantle convection from 65 Ma to the present day. We test our models with different viscosities of cratons and asthenosphere along with varying strengths of temperature-dependent viscosities of the Reunion plume to examine how these parameters influence the craton thinning. We find that in the presence of temperature-dependent viscosity, plume-induced thermomechanical erosion could potentially reduce the thickness of the Indian craton. About ~130 km (43%) reduction of cratonic root is observed in our models if the temperature dependence of viscosity is high. Our results also suggest that plume can lubricate the lithosphere-asthenosphere boundary underneath the Indian plate. Such lubrication might have reduced the viscous drag between the lithosphere and asthenosphere, resulting in a long sustaining higher velocity of the Indian plate since 65 Ma.