Connection between a subcontinental plume and the mid-lithospheric
discontinuity leads to fast and intense craton lithospheric thinning
Abstract
Removal and thinning of cratonic lithosphere is believed to have
occurred under different tectonic settings, for example, near subduction
zones and above mantle plumes. Subduction-induced cratonic modification
has been widely discussed; however, the mechanisms and dynamic processes
of plume-induced lithospheric removal remain elusive and require further
systematic investigation. In this study, we conduct a series of 2-D
thermo-mechanical models to explore the dynamics of the removal and
thinning of cratonic lithosphere due to the interaction between a mantle
plume and a weak mid-lithosphere discontinuity (MLD) layer. Our modeling
results suggest that the interaction between a mantle plume and weak MLD
layer can lead to a large-scale removal of the cratonic lithosphere as
long as the connection between the hot upwelling and weak MLD layer is
satisfied. The presence of a vertical lithospheric weak zone and its
closeness to the plume center play critical roles in creating a
connection between the weak MLD and hot plume/asthenosphere.
Furthermore, delamination of cratonic lithosphere is favored by a larger
plume radius/volume, a higher plume temperature anomaly, and a lower
viscosity of the MLD layer. A systematic comparison between
subduction-induced and plume-induced lithospheric thinning patterns is
further conducted. We summarize their significant differences on the
origin and migration of melt generation, the water content in melts, and
topographic evolution. The combination of numerical models and
geological/geophysical observations indicates that mantle plume-MLD
interaction may have played a crucial role in lithospheric removal
beneath South Indian, South American and North Siberian Cratons.