Abstract
Mid-ocean ridges and mantle plumes are two attractive windows to allow us to get a glimpse of mantle structure and dynamics. Dynamical interaction between ridge and plume processes have been widely proposed and studied, particularly in terms of ridge suction. However, the effects of plate drag on plumes and plume-ridge interaction remains poorly understood. Quantification of suction versus plate drag between ridges and plumes remains absent. Here we use 2D thermomechanical numerical models to study the plume-ridge interaction, exploring the effects of (i) the spreading rate of ridge, (ii) the plume radius, and (iii) the plume-ridge distance systematically. Our numerical experiments suggest two different geodynamic regimes: (1) plume motion prone to ridge suction is favored by strong buoyant mantle plume and short plume-ridge distance, and (2) plume migration driven by plate drag is promoted by fast-ridge spreading rate. Our results highlight fast-spreading ridges exert strong plate dragging force, rather than suction on plume motion, which sheds new light on the natural observations of plume absence along the fast-spreading ridges, such as the East Pacific Rises.
Highlights
Mid-ocean ridges (MORs) and hotspots are two main regions for deep material recycling to the surface of the Earth
Of up to 50 mantle plumes revealed by seismic tomography (French and Romanowicz, 2015; Montelli et al, 2004), more than 20 plumes are found to be associated with nearby ridges (Ito et al, 2003)
We conduct a series of numerical experiments to investigate ridge suction versus plate drag acts on plumes
Summary
Mid-ocean ridges (MORs) and hotspots are two main regions for deep material recycling to the surface of the Earth. These two units are not always isolated but showing strong interactions in some cases, termed as plume-ridge interaction (Morgan, 1971). The major factors affecting ridge suction on plumes includes ridge spreading rate, plume buoyancy flux and their spatial distance (Fig. 1b; François et al, 2018; Kincaid et al, 1996; Ribe et al, 1995; Ribe, 1996; Sleep, 1997). Most plume-ridge interaction systems links to slow-spreading ridges (< 2.5 cm/yr; Gerya, 2012) and small mantle plumes and short plume-ridge distances. Systematical studies investigating these parameters remain scarce regarding the effects of these parameters on the behavior of plume-ridge interaction
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