Plume-Lithosphere interaction and its effect on surface topography: A theoretical and experimental approach

Abstract

Plumes are hot buoyant materials rising from the D’’ layer in the lower mantle. When plumes hit the base of lithosphere, it forms a surface topography, lateral flow and lithospheric erosion. Lithospheric topography depends on viscosity, density of the buoyant plume material as well as on the rheological zoning in the lithosphere. In this thesis, the control of rheological parameters like viscosity contrast between plume and mantle is tested in physical experiments to understand the difference in dynamics of plume ascent and lithosphere interaction. Plume impinging the lithosphere generates under plating and surface topography. In order to quantitatively validate the result, Finite Element Modelling simulations are performed using ASPECT. The model also incorporates a rift zone in the lithosphere. Separation distance between plume axis and rift axis as well as rift velocity controls the ascent of plumes in lithospheric mantle. The viscosity of the plumes with respect to mantle in responsible for different morphology of plumes and different interactions. Lithosphere viscosity plays a crucial role in determining the type of lithospheric delamination. Maximum and minimum topography in an active rift zone is influenced by the plume impinging the base.