Name
Subduction erosion and crustal relamination: insights from 2D numerical models
Date & Time
Monday, May 8, 2023, 10:00 AM - 10:15 AM
Description
Subduction erosion is a process in which the continental crust is eroded by the subducting plate and carried down the subduction channel. Although this has been observed at many convergent margins (e.g. SW Japan, central Andes), the fate of the eroded continental material is not fully understood. Various studies have argued that the material may be transported to the deep mantle, may undergo melting and be incorporated in arc magmas, or may buoyantly detach from the subducting plate and underplate the overlying continent (i.e., relamination). In this study, 2D thermal-mechanical models are used to investigate the dynamics of subduction erosion and relamination. Our model shows that subduction erosion occurs in models with relatively weak lithosphere and high convergent rate. With thick continental lithosphere, eroded material is carried to 100-150 km depth, before upwelling and being emplaced below and within the deep continental mantle lithosphere. To get the eroded material immediately below the crust, the mantle lithosphere must be initially thin or must undergo thinning through gravitational removal. Our models demonstrate that if thinning via delamination occurs, there is an enhanced rate of subduction erosion, suggesting that there may be dynamic feedbacks between delamination and subduction erosion. They also indicate that relamination may be an important process for thickening the crust in the absence of significant shortening. This can provide insights into the Puna area of the central Andes where there is little mantle lithosphere and where crustal shortening is not enough to account for the observed crustal thickness.
Location Name
Aspen
Full Address
Banff Park Lodge Resort Hotel & Conference Centre
201 Lynx St
Banff AB T1L 1K5
Canada
Abstract
Subduction erosion is a process in which the continental crust is eroded by the subducting plate and carried down the subduction channel. Although this has been observed at many convergent margins (e.g. SW Japan, central Andes), the fate of the eroded continental material is not fully understood. Various studies have argued that the material may be transported to the deep mantle, may undergo melting and be incorporated in arc magmas, or may buoyantly detach from the subducting plate and underplate the overlying continent (i.e., relamination). In this study, 2D thermal-mechanical models are used to investigate the dynamics of subduction erosion and relamination. Our model shows that subduction erosion occurs in models with relatively weak lithosphere and high convergent rate. With thick continental lithosphere, eroded material is carried to 100-150 km depth, before upwelling and being emplaced below and within the deep continental mantle lithosphere. To get the eroded material immediately below the crust, the mantle lithosphere must be initially thin or must undergo thinning through gravitational removal. Our models demonstrate that if thinning via delamination occurs, there is an enhanced rate of subduction erosion, suggesting that there may be dynamic feedbacks between delamination and subduction erosion. They also indicate that relamination may be an important process for thickening the crust in the absence of significant shortening. This can provide insights into the Puna area of the central Andes where there is little mantle lithosphere and where crustal shortening is not enough to account for the observed crustal thickness.
Session Type
Breakout Session