09:00 〜 09:15
[SIT14-01] Weakening of continental lithosphere by baby plume: insights from numerical models
キーワード：plume emplacement, plume-driven lithospheric weakening, dynamic topography, lithosphere asthenosphere boundary, numerical modeling
The process of baby (small) 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 mechanical and thermal weakening. In this study, we quantitatively evaluated the effects of baby plume-driven pre-defined weakening of the continental lithospheric mantle and crust on the dynamic topography and LAB depth changes using a series of two-dimensional numerical models. Model calculations showed that baby plume-driven pre-defined weakening developed short-wavelength dynamic topography and LAB depth reduction through both mechanical and thermal erosion of the lithospheric mantle by the plume. A higher degree of weakening decreased the lithospheric strength and reduced the LAB depth, thereby transforming the short-wavelength topography from depression to elevation as the extensional kinematics changed to compression. The comparison of our model findings with the topography, lithospheric strength, and LAB depth from natural small-scale plume emplacement zones indicates that our findings explain the evidences assimilated from the natural observations.