Data for "Mechanisms of Lithospheric Dripping in Earth’s Convecting Mantle: Implications for Tectonic Switching"

Cold, dense lithospheric materials often drip into the underlying hotter and relatively less dense mantle regions. This process plays a crucial role in driving material recycling in Earth’s geodynamic evolution. It is now well-accepted that lithospheric dripping is initiated by gravitational instabilities, which grow vertically down to form isolated lithospheric drips that sink in the mantle. Here, we use computational fluid-dynamics (CFD) model simulations to systematically investigate the mechanisms of lithospheric dripping under varying thermo-chemical conditions in the geodynamic settings. This study also explores how each mechanism can in turn control the mantle convection styles (whole-mantle versus layered convection structures). Our model simulations incorporate the following parameters: lithospheric buoyancy and viscosity contrast, mid-mantle phase changes and metamorphic changes of the gabbroic crust to eclogite, and show dripping in three distinct mechanisms- Mechanism 1: clustering of drips into superdrip structures, which sink across the 660 km mid-mantle transition zone, leading to formation of whole-mantle circulation; Mechanism 2: stagnation of drips at the ~660 km boundary, accompanied by partitioning of the mantle convective circulations; and Mechanism 3: asymmetric drip growth into keel structures (proto-subduction zones), leaving the lower mantle almost undisturbed. Replacement of Mechanism 1 by 2 results in a transition from whole-mantle to layered convection, which again transforms in whole-mantle circulations on larger wavelengths as Mechanism 3 becomes active. This article finally discusses the impacts of lithospheric dripping mechanisms on Earth’s geodynamic evolution, including the transition from early stagnant-lid to modern plate tectonics.