Plate Tectonics as a Far- From- Equilibrium Self-Organized System

Contained fluids heated from below spontaneously organize into convection cells when sufficiently far from conductive equilibrium. Fluids can also be organized by surface tension and other forces at the top. Plate tectonics was once regarded as passive motion of plates on top of mantle convection cells but it now appears that continents and plate tectonics organize the flow in the mantle. The flow is driven by instability of the cold surface layer and near-surface lateral temperature gradients. Plate tectonics may be a self-driven far-from-equilibrium system that organizes itself by dissipation in and between the plates. In this case the mantle is a passive provider of energy and material. The effect of pressure suppresses the role of the lower thermal boundary layer. I suggest that the state of stress in the lithosphere defines the plates, plate boundaries and locations of midplate volcanism, and that fluctuations in stress are responsible for global plate reorganizations and evolution of volcanic chains. Stress controls the orientations and activity of volcanic chains. The state of stress in the lithosphere is probably more important than the temperature of the mantle in localizing volcanism, although the normal variations of temperature in the mantle influence the topography and stress of the plate. Stress also controls the strength of the lithosphere. Volcanic chains should be regarded as stress-gauges and not as indicators of absolute plate motions. Changes in the orientation and magmatic activity of volcanic chains (e. g. Hawaiian and Emperor chains) cannot be due to abrupt changes in plate motions but can reflect changes in stress.