title: Plate tectonics on the Earth triggered by plume-induced subduction initiation.
abstract: Scientific theories of how subduction and plate tectonics began on Earth--and what the tectonic structure of Earth was before this--remain enigmatic and contentious. Understanding viable scenarios for the onset of subduction and plate tectonics is hampered by the fact that subduction initiation processes must have been markedly different before the onset of global plate tectonics because most present-day subduction initiation mechanisms require acting plate forces and existing zones of lithospheric weakness, which are both consequences of plate tectonics. However, plume-induced subduction initiation could have started the first subduction zone without the help of plate tectonics. Here, we test this mechanism using high-resolution three-dimensional numerical thermomechanical modelling. We demonstrate that three key physical factors combine to trigger self-sustained subduction: (1) a strong, negatively buoyant oceanic lithosphere; (2) focused magmatic weakening and thinning of lithosphere above the plume; and (3) lubrication of the slab interface by hydrated crust. We also show that plume-induced subduction could only have been feasible in the hotter early Earth for old oceanic plates. In contrast, younger plates favoured episodic lithospheric drips rather than self-sustained subduction and global plate tectonics.
authors.affiliation: Department of Earth Sciences, ETH-Zurich, Sonneggstrasse 5, 8092 Zurich, Switzerland.
authors.forename: T V
authors.initials: TV
authors.lastname: Gerya
authors.affiliation: Geosciences Department, University of Texas at Dallas, Richardson, Texas 75083-0688, USA.
authors.forename: R J
authors.initials: RJ
authors.lastname: Stern
authors.affiliation: GFZ German Research Center for Geosciences, Heinrich-Mann-Allee 18/19, 14473 Potsdam, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Baes
authors.affiliation: GFZ German Research Center for Geosciences, Heinrich-Mann-Allee 18/19, 14473 Potsdam, Germany.|Institute of Earth and Environmental Science, University of Potsdam, Karl-Liebknecht-Straße 24-25, 14476 Potsdam-Golm, Germany.
authors.forename: S V
authors.initials: SV
authors.lastname: Sobolev
authors.affiliation: Department of Earth and Environmental Sciences, Korea University, Seoul 136-701, South Korea.
authors.forename: S A
authors.initials: SA
authors.lastname: Whattam