Lithospheric weakening by a small-scale plume and its geodynamic implications

• Published in: Earth and planetary science letters 2024-01, Vol.626, p.118514, Article 118514
• Main Authors: Dasgupta, Ritabrata, Lee, Changyeol
• Format: Article
• Language: English
• Subjects: dynamic topography; lithosphere asthenosphere boundary (LAB); lithospheric strength; numerical modeling; plume-driven lithospheric weakening; small-scale plume emplacement
• ISSN: 0012-821X; 1385-013X
• DOI: 10.1016/j.epsl.2023.118514

•Predefined plume-driven weakening was considered in small-scale plume-lithosphere interaction modeling.•Plume-driven weakening reduces the lithospheric strength and LAB depth, yielding a short-wavelength topography.•Enhanced weakening removes lithospheric mantle further, reducing the LAB depth.•Enhanced weakening increases topographic undulations, converting short-wavelength depressions to elevations.•The model explains the topography, lithospheric strength, and LAB depth of natural small-scale plume-emplaced zones. The process of small-scale mantle plume emplacement within the continental lithosphere influences the dynamic topography and architecture of the lithosphere-asthenosphere boundary (LAB). Furthermore, plume emplacement alters the rheology of the crust and lithospheric mantle through melt-driven, mechanical and thermal weakening. Previous studies of plume emplacement within the lithosphere have described these outcomes, albeit without considering plume-driven weakening. In this study, we quantitatively evaluated the effects of small-scale plume-driven predefined weakening of the continental lithospheric mantle and crust on dynamic topography and LAB depth changes using a series of two-dimensional numerical models. Model calculations showed that small plume-driven predefined weakening led to short-wavelength dynamic topography and LAB depth reduction through both mechanical and thermal erosion of the lithospheric mantle by the plume. An increase in the degree of weakening decreased the lithospheric strength and reduced the LAB depth, thereby transforming the short-wavelength topography from depressions to elevations as the extensional kinematics shifted to compression. Our model findings explain the topography, lithospheric strength, and LAB depth constrained from natural small-scale plume emplacement zones.